Intergovernmental Panel on Climate Change: Global Warming 1.5 Degrees C Copyrighted
November 19, 2018
City of Dubuque Consent Items # 10.
ITEM TITLE: Intergovernmental Panel on Climate Change: Global
Warming of 1 .5 Degrees C
SUMMARY: City Manager transmitting information from the
Intergovernmental Panel on Climate Change (IPCC) that
addresses the impact of global warming.
SUGGESTED DISPOSITION: Suggested Disposition: Receive and File
ATTACHMENTS:
Description Type
IPCC Press Release Supporting Documentation
Headlines Supporting Documentation
IPCC FAQs Supporting Documentation
IPPC Global Warming of 1.5 Degrees C Supporting Documentation
ipCC
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2018/24/PR
IPCC PRESS RELEHSE
8 October 2018
Summary for Policymakerz of IPCC Special Report on Global W arming of 1.5°C approved by
governmen[z
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"The good news is that some of the kinds of actions that would be needed to limit global warming to
1.5°C are already underway around the world, but they would need to accelerate," said Valerie
Masson-Delmotte, Co-Chair of Working Group I.
The report finds that limiting global warming to 1.5°C would require "rapid and far-reaching"
transitions in land, energy, industry, buildings, transport, and cities. Global net human-caused
emissions of carbon dioxide (COZ) would need to fall by about 45 percent from 2010 levels by 2030,
reaching 'net zero' around 2050. This means that any remaining emissions would need to be
balanced by removing COZfrom the air.
"Limiting warming to 1 .5°C is possible within the laws of chemistry and physics but doing so would
require unprecedented changes," said Jim Skea, Co-Chair of IPCC Working Group III.
Allowing the global temperature to temporarily exceed or 'overshooY 1.5°C would mean a greater
reliance on techniques that remove COZfrom the air to return global temperature to below 1.5°C by
2100. The effectiveness of such techniques are unproven at large scale and some may carry
significant risks for sustainable development, the report notes.
"Limiting global warming to 1.5°C compared with 2°C would reduce challenging impacts on
ecosystems, human health and well-being, making it easier to achieve the United Nations
Sustainable Development Goals," said Priyardarshi Shukla, Co-Chair of IPCC Working Group III.
The decisions we make today are critical in ensuring a safe and sustainable world for everyone,
both now and in the future, said Debra Roberts, Co-Chair of IPCC Working Group II.
"This report gives policymakers and practitioners the information they need to make decisions that
tackle climate change while considering local context and people's needs. The next few years are
probably the most important in our history," she said.
The IPCC is the leading world body for assessing the science related to climate change, its impacts
and potential future risks, and possible response options.
The report was prepared under the scientific leadership of all three IPCC working groups. Working
Group I assesses the physical science basis of climate change; Working Group II addresses
impacts, adaptation and vulnerability; and Working Group III deals with the mitigation of climate
change.
The Paris Agreement adopted by 195 nations at the 21st Conference of the Parties to the UNFCCC
in December 2015 included the aim of strengthening the global response to the threat of climate
change by "holding the increase in the global average temperature to well below 2°C above pre-
industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial
levels."
As part of the decision to adopt the Paris Agreement, the IPCC was invited to produce, in 2018, a
Special Report on global warming of 1.5°C above pre-industrial levels and related global
greenhouse gas emission pathways. The IPCC accepted the invitation, adding that the Special
Report would look at these issues in the context of strengthening the global response to the threat
of climate change, sustainable development, and efforts to eradicate poverty.
Global Warming of 1.5°C is the first in a series of Special Reports to be produced in the IPCC's
Sixth Assessment Cycle. Next year the IPCC will release the Special Report on the Ocean and
Cryosphere in a Changing Climate, and Climate Change and Land, which looks at how climate
change affects land use.
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The Special Reporton Global Warmiqg ofi6 �C , known as SR15, Isbeing preparetl In responset�
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there is agreement in the scientific community, where there are differences of opinion, and where
further research is needed. It does not conduct its own research.
To produce its reports, the IPCC mobilizes hundreds of scientists. These scientists and officials are
drawn from diverse backgrounds. Only a dozen permanent staff work in the IPCC's Secretariat.
The IPCC has three working groups: Working Group I, dealing with the physical science basis of
climate change; Working Group II, dealing with impacts, adaptation and vulnerability; and Working
Group III, dealing with the mitigation of climate change. It also has a Task Force on National
Greenhouse Gas Inventories that develops methodologies for measuring emissions and removals.
IPCC Assessment Reports consist of contributions from each of the three working groups and a
Synthesis Report. Special Reports undertake an assessment of cross-disciplinary issues that span
more than one working group and are shorter and more focused than the main assessments.
Sixth Assessment Cycle
At its 41�` Session in February 2015, the IPCC decided to produce a Sixth Assessment Report
(AR6). At its 42"' Session in October 2015 it elected a new Bureau that would oversee the work on
this report and Special Reports to be produced in the assessment cycle. At its 43rd Session in April
2016, it decided to produce three Special Reports, a Methodology Report and AR6.
The Methodology Report to refine the 2006 IPCC Guidelines for National Greenhouse Gas
Inventories will be delivered in 2019. Besides Global Warming of 1.5°C, the IPCC will finalize two
further special reports in 2019: the Special Report on the Ocean and Cryosphere in a Changing
Climate and Climate Change and Land: an IPCC special report on climate change, desertification,
land degradation, sustainable land management, food security, and greenhouse gas fluxes in
terrestrial ecosystems. The AR6 Synthesis Report will be finalized in the first half of 2022, following
the three working group contributions to AR6 in 2021.
For more information, including links to the IPCC reports, go to:www.ipcc.ch
-4-
Global Warming of 1 .5 °C an IPCC special report on the impacts of global warming of
1 .5 °C above pre-industrial levels and related global greenhouse gas emission
pathways, in the context of strengthening the global response to the threat of climate
change, sustainable development, and efforts to eradicate poverty
Headline Statements
A. Understanding Global Warming of 1.5°C4
A1 . Human activities are estimated to have caused approximately 1 .0°C of global
warming above pre-industrial levels, with a likely range of 0.8°C to 1 .2°C. Global
warming is likely to reach 1 .5°C between 2030 and 2052 if it continues to increase at
the current rate (high confidence).
A.2. Warming from anthropogenic emissions from the pre-industrial period to the
present will persist for centuries to millennia and will continue to cause further long-
term changes in the climate system, such as sea level rise, with associated impacts
(high confidence), but these emissions alone are unlikely to cause global warming of
1 .5°C (medium confidence).
A3. Climate-related risks for natural and human systems are higher for global
warming of 1 .5°C than at present, but lower than at 2°C (high confidence). These
risks depend on the magnitude and rate of warming, geographic location, levels of
development and vulnerability, and on the choices and implementation of adaptation
and mitigation options (high confidence).
B. Projected Climate Change, Potential Impacts and Associated Risks
B1 . Climate models project robust7 differences in regional climate characteristics
between present-day and global warming of 1 .5°C, and between 1 .5°C and 2°C.
These differences include increases in: mean temperature in most land and ocean
regions (high confidence), hot extremes in most inhabited regions (high confidence),
heavy precipitation in several regions (medium confidence), and the probability of
drought and precipitation deficits in some regions (medium confidence).
B2. By 2100, global mean sea level rise is projected to be around 0.1 metre lower
with global warming of 1 .5°C compared to 2°C (medium confidence). Sea level will
continue to rise well beyond 2100 (high confidence), and the magnitude and rate of
this rise depends on future emission pathways. A slower rate of sea level rise
enables greater opportunities for adaptation in the human and ecological systems of
small islands, low-lying coastal areas and deltas (medium confidence).
B3. On land, impacts on biodiversity and ecosystems, including species loss and
extinction, are projected to be lower at 1 .5°C of global warming compared to 2°C.
Limiting global warming to 1 .5°C compared to 2°C is projected to lower the impacts
on terrestrial, freshwater, and coastal ecosystems and to retain more of their services
to humans (high confidence).
B4. Limiting global warming to 1 .5°C compared to 2°C is projected to reduce
increases in ocean temperature as well as associated increases in ocean acidity and
decreases in ocean oxygen levels (high confidence). Consequently, limiting global
warming to 1 .5°C is projected to reduce risks to marine biodiversity, fisheries, and
ecosystems, and their functions and services to humans, as illustrated by recent
changes to Arctic sea ice and warm water coral reef ecosystems (high confidence).
B5. Climate-related risks to health, livelihoods, food security, water supply, human
security, and economic growth are projected to increase with global warming of 1 .5°C
and increase further with 2°C.
B6. Most adaptation needs will be lower for global warming of 1 .5°C compared to 2°C
(high confidence). There are a wide range of adaptation options that can reduce the
risks of climate change (high confidence). There are limits to adaptation and adaptive
capacity for some human and natural systems at global warming of 1 .5°C, with
associated losses (medium confidence). The number and availability of adaptation
options vary by sector (medium confidence).
C. Emission Pathways and System Transitions Consistent with 1.5°C Global
Warming
C1 . In model pathways with no or limited overshoot of 1 .5°C, global net
anthropogenic CO2 emissions decline by about 45°k from 2010 levels by 2030 (40—
60°k interquartile range), reaching net zero around 2050 (2045-2055 interquartile
range). For limiting global warming to below 2°C, CO2 emissions are projected to
decline by about 20°k by 2030 in most pathways (10-30°k interquartile range) and
reach net zero around 2075 (2065-2080 interquartile range). Non-0O2 emissions in
pathways that limit global warming to 1 .5°C show deep reductions that are similar to
those in pathways limiting warming to 2°C (high confidence).
C2. Pathways limiting global warming to 1 .5°C with no or limited overshoot would
require rapid and far-reaching transitions in energy, land, urban and infrastructure
(including transport and buildings), and industrial systems (high confidence). These
systems transitions are unprecedented in terms of scale, but not necessarily in terms
of speed, and imply deep emissions reductions in all sectors, a wide portfolio of
mitigation options and a significant upscaling of investments in those options
(medium confidence).
C3. All pathways that limit global warming to 1 .5°C with limited or no overshoot
project the use of carbon dioxide removal (CDR) on the order of 100-1000 GtCO2
over the 21 st century. CDR would be used to compensate for residual emissions
and, in most cases, achieve net negative emissions to return global warming to 1 .5°C
following a peak (high confidence). CDR deployment of several hundreds of GtCO2
is subject to multiple feasibility and sustainability constraints (high confidence).
Significant near-term emissions reductions and measures to lower energy and land
demand can limit CDR deployment to a few hundred GtCO2 without reliance on
bioenergy with carbon capture and storage (BECCS) (high confidence).
D. Strengthening the Global Response in the Context of Sustainable
Development and Efforts to Eradicate Poverty
D1 . Estimates of the global emissions outcome of current nationally stated mitigation
ambitions as submitted under the Paris Agreement would lead to global greenhouse
gas emissions in 2030 of 52-58 GtCO2eq yr-1 (medium confidence). Pathways
reflecting these ambitions would not limit global warming to 1 .5°C, even if
supplemented by very challenging increases in the scale and ambition of emissions
reductions after 2030 (high confidence). Avoiding overshoot and reliance on future
largescale deployment of carbon dioxide removal (CDR) can only be achieved if
global CO2 emissions start to decline well before 2030 (high confidence).
D2. The avoided climate change impacts on sustainable development, eradication of
poverty and reducing inequalities would be greater if global warming were limited to
1 .5°C rather than 2°C, if mitigation and adaptation synergies are maximized while
trade-offs are minimized (high confidence).
D3. Adaptation options specific to national contexts, if carefully selected together with
enabling conditions, will have benefits for sustainable development and poverty
reduction with global warming of 1 .5°C, although trade-offs are possible (high
confidence).
D4. Mitigation options consistent with 1 .5°C pathways are associated with multiple
synergies and trade-offs across the Sustainable Development Goals (SDGs). While
the total number of possible synergies exceeds the number of trade-offs, their net
effect will depend on the pace and magnitude of changes, the composition of the
mitigation portfolio and the management of the transition (high confidence).
D5. Limiting the risks from global warming of 1 .5°C in the context of sustainable
development and poverty eradication implies system transitions that can be enabled
by an increase of adaptation and mitigation investments, policy instruments, the
acceleration of technological innovation and behaviour changes (high confidence).
D6. Sustainable development supports, and often enables, the fundamental societal
and systems transitions and transformations that help limit global warming to 1 .5°C.
Such changes facilitate the pursuit of climate-resilient development pathways that
achieve ambitious mitigation and adaptation in conjunction with poverty eradication
and efforts to reduce inequalities (high confidence).
D7. Strengthening the capacities for climate action of national and sub-national
authorities, civil society, the private sector, indigenous peoples and local
communities can support the implementation of ambitious actions implied by limiting
global warming to 1 .5°C (high confidence). International cooperation can provide an
enabling environment for this to be achieved in all countries and for all people, in the
context of sustainable development. International cooperation is a critical enabler for
developing countries and vulnerable regions (high confidence).
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
1
2 IPCC Special Report on Global Warming of LS°C
3 Frequently Asked Questions
4
5
6 Drafting Authors: Myles Allen(LJK), Heleen de Coninck(Netherlands), Sarah Connors (LJK),
7 Francois Engelbrecht(South Africa), Marion Ferrat(LJK/France), James Ford(LJK), Sabine Fuss
8 (Germany),Nigel Hawtin(UK), Ove Hoegh-Guldberg(Australia),Daniela Jacob (Germany),Debora
9 Ley(Guatemala/Mexico), Diana Liverman(USA),Valerie Masson-Delmotte(France),Richard Millar
10 (LJK), Peter Newman(Australia), Anthony Payne (LJK),Rosa Perez(Philippines), Roz Pidcock(LJK),
11 Joeri Rogelj (Austria/Belgium), Sonia Seneviratne(Switzerland), Chandni Singh(India), Michael
12 Taylar(Jamaica),Petra Tschakert(Australia/Austria).
13
14 Draft Note: 06/10/2018-FAQs are subject to copy editing and trickle backs.
15
16
17 FAQ L1: Why Are We Talking about 1.5°C?....................................................................2
18 FAQ 1.2: How Close Are We to 1.5°C?..........................................................................4
19 FAQ 2.1: What Kind of Pathways Limit Warming to 1.5°C and Are We on Track?............................6
20 FAQ 2.2: What Do Energy Supply and Demand Have to do with Limiting Warming to 1.5°C?........8
21 FAQ 3.1: What are the Impacts of 1.5°C and 2°C of Warming?...........................................10
22 FAQ 4.1: What Transitions Could Enable Limiting Global Warming to 1.5°C?.........................12
23 FAQ 4.2: What are Carbon Dioxide Removal and Negative Emissions?.................................15
24 FAQ 4.3: Why is Adaptation Important in a 1.5°C-Warmer World ........................................17
25 FAQ 5.1: What Are the Connections between Sustainable Development and Limiting Global
26 Warxning to 1.5°C above Pre-Industrial Levels? .................................................19
27 FAQ 5.2: What are the Pathways to Achieving Poverty Reduction and Reducing Inequalities While
28 Reaching the 1.5°C World? .........................................................................22
29
30
FAQ-1 Total pages: 23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
1 FAQ L1: Why Are We Talking about LS°C?
2
3 Summary: Climate change represents an urgent and potentially irreversible threat to human societies
4 and the planet.In recognition of this, the overwhelming majority of countries around the world
5 adopted the Paris Agreement in December 2015, the central aim of which includes pursuing efforts to
6 limit global temperature rise to 1.5°C.In doing so, these countries, through the United Nations
7 FrameworkConvention on Climate Change (CINFCCC), also invited theIPCC to provide a Special
8 Report on the impacts ofglobal warming of I.5°C above pre-industrial levels and related global
9 greenhouse gas emissions pathways.
10
11 At the 21st Conference of the Parties (COP21) in December 2015, 195 nations adopted the Paris
12 Agreement'. The first instrument of its kind,the landmark agreement includes the aim to strengthen
13 the global response to the threat of climate change by `holding the increase in the global average
14 temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature
15 increase to 1.5°C above pre-industrial levels'.
16
17 The first iJNFCCC document to mention a limit to global warxning of 1.5°C was the Cancun
18 Agreement, adopted at the sixteenth COP(COPl� in 2010. The Cancun Agreement established a
19 process to periodically review the `adequacy of the long-terxn global goal (LTGG) in the light of the
20 ultimate objective of the Convention and the overall progress made towards achieving the LTGG,
21 including a consideration of the implementation of the commihnents under the Convention'. The
22 definition of LTGG in the Cancun Agreement was `to hold the increase in global average temperature
23 below 2°C above pre-industrial levels'. The agreement also recognised the need to consider
24 `strengthening the long term global goal on the basis of the best available scientific knowledge...to a
25 global average temperature rise of 1.5°C'.
26
27 Beginning in 2013 and ending at the COP21 in Paris in 2015,the first review period of the long-term
28 global goal largely consisted of the Strucbxred Expert Dialogue(SED). This was a fact-finding,face-
29 to-face exchange of views between invited experts and iJNFCCC delegates. The final report of the
30 SEDZ concluded that `in some regions and vulnerable ecosystems,high risks are projected even for
31 warming above 1.5°C'. The SED report also suggested that Parties would profit from restating the
32 temperature limit of the long-term global goal as a `defence line' or `buffer zone', instead of a
33 `guardraiP up to which all would be safe, adding that this new understanding would `probably also
34 favour emission pathways that will limit warxning to a range of temperatures below 2°C'. Specifically
35 on strengthening the temperature limit of 2°C,the SED's key message was: `While science on the
36 1.5°C warxning limit is less robust, efforts should be made to push the defence line as low as possible'.
37 The findings of the SED, in turn,fed into the draft decision adopted at COP21.
38
39 With the adoption of the Paris Agreement,the iJNFCCC invited the IPCC to provide a Special Repart
40 in 2018 on `the impacts of global warming of 1.5°C above pre-industrial levels and related global
41 greenhouse gas emissions pathways'. The request was that the report,known as SR1.5, should not
42 only assess what a 1.5°C warmer world would look like but also the different pathways by which
43 global temperature rise could be limited to 1.5°C. In 2016,the IPCC accepted the invitation, adding
44 that the Special Repart would also look at these issues in the context of strengthening the global
45 response to the threat of climate change, sustainable development and efforts to eradicate poverly.
46
47 The combination of rising exposure to climate change and the fact that there is a limited capacity to
48 adapt to its impacts amplifies the risks posed by warxning of 1.5°C and 2°C. This is particularly true
i Paris AgreementFCCC/CP/2015/10/Add.l https://unfccc.inUdocuments/9097
� Structured ExpertDialogue(SED)final report FCCC/SB/2015/INF.1 https://unfccc.inUdocuments/8707
FAQ-2 Total pages: 23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
1 for developing and island countries in the tropics and other vulnerable countries and areas. The risks
2 posed by global warming of 1.5°C are greater than for present-day conditions but lower than at 2°C.
3
FAQ1.1: Timeline of 1.5°C
Milestones in the IPCCs preparalion of the Special Reporl on Global Warming of 7.5"C and some relevan7 events
in ihe history of in[ernational climate negotiations
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4
5 FAQL1, Figure 1: A timeline of notable dates in preparing the IPCC Special Report on Global
6 Warming of 1.5°C(blue) embedded within processes and milestones of the United Nations
7 Framewark Convention on Climate Change(iJNFCCC; grey), including events that may be relevant
8 for discussion of temperature limits.
9
FAQ-3 Total pages: 23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
1 FAQ 1.2: How Close Are We to LS°C?
2
3 Summary:Human-induced warming has already reached about 1°C above pre-industrial levels at the
4 time of writing of this Special Report. By the decade 200�r2015, human activity had warmed the
5 world by 0.87°C(f012°C) compared pre-industrial times (1850-1900).Ifthe currentwarming rate
6 continues, the world would reach human-induced global warming of I.5°C around 2040.
7
8 Under the 2015 Paris Agreement, countries agreed to cut greenhouse gas emissions with a view to
9 `holding the increase in the global average temperature to well below 2°C above pre-industrial levels
10 and pursuing effarts to limit the temperabxre increase to 1.5°C above pre-industrial levels'. While the
11 overall intention of strengthening the global response to climate change is clear,the Paris Agreement
12 does not specify precisely what is meant by `global average temperabxre', or what period in history
13 should be considered `pre-industriaP. To answer the question of how close are we to 1.5°C of
14 warming, we need to first be clear about how both terms are defined in this Special Report.
15
16 The choice of pre-industrial reference period, along with the method used to calculate global average
17 temperature, can alter scientists' estimates of historical warming by a couple of tenths of a degree
18 Celsius. Such differences become important in the context of a global temperabxre limit just half a
19 degree above where we are now. But provided consistent definitions are used,they do not affect our
20 understanding of how human activity is influencing the climate.
21
22 In principle, `pre-industrial levels' could refer to any period of time before the start of the industrial
23 revolution. But the number of direct temperabxre measurements decreases as we go back in time.
24 Defining a `pre-industrial' reference period is, therefore, a compromise between the reliability of the
25 temperature inforxnation and how representative it is of truly pre-industrial conditions. Some pre-
26 industrial periods are cooler than others for purely natural reasons. This could be because of
27 spontaneous climate variability or the response of the climate to natural perturbations, such as volcanic
28 eruptions and variations in the sun's activity. This IPCC Special Report on Global Warming of 1.5°C
29 uses the reference period 1850-1900 to represent pre-industrial conditions. This is the earliest period
30 with near-global observations and is the reference period used as an approximation of pre-industrial
31 temperatures in the IPCC Fifth Assessment Report.
32
33 Once scientists have defined `pre-industrial', the next step is to calculate the amount of warming at
34 any given time relative to that reference period. In this report,warxning is defined as the increase in the
35 30-year global average of combined temperature over land and at the ocean surface. The 30-year
36 timespan accounts far the effect of nabxral variability,which can cause global temperatures to
37 fluctuate from one year to the next. For example, 2015 and 2016 were both affected by a strong El
38 Nino event,which amplified the underlying human-caused warxning.
39
40 In the decade 2006-2015,warming reached 0.87°C(f0.12°C)relative to 185�1900,predominantly
41 due to human activity increasing the amount of greenhouse gases in the atmosphere. Given that global
42 temperature is currently rising by 0.2°C(f0.1°C)per decade,human-induced warxning reached 1°C
43 above pre-industrial levels around 2017 and, if this pace of warxning continues, would reach 1.5°C
44 around 2040.
45
46 While the change in global average temperature tells researchers about how the planet as a whole is
47 changing, looking more closely at specific regions, countries and seasons reveals important details.
48 Since the 1970s, most land regions have been warxning faster than the global average,for example.
49 This means that warxning in many regions has already exceeded 1.5°C above pre-industrial levels.
50 Over a fifth of the global population live in regions that have already experienced warxning in at least
51 one season that is greater than 1.5°C above pre-industrial levels.
52
FAQ-4 Total pages: 23
Re-trickleback version Frequently Asked Questions IPCC SR1.5
FAQ12:How close are we to ?
Human-intlucetl wartning reachetl appmximately 1°C above pre-intlustrial levels in 2011
Current
warming rate
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1
2 FAQ1.2, NYgure 1: Human-induced wartrting reached approxunately 1°C above pre-industrial levele
3 in 2017. At the pieeent rate,global temperaturee would reach 1.5°C uound 2040. Stylized 1.5°C
4 pathway ehown here involvee emieeion reductione beginrting immediately, and COz emieeione
5 reaching zero by 2055.
6
7
8
9
FA�S Total pages:23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
1 FAQ 2.1: What Kind of Pathways Limit Warming to 1.5°C and Are We on Track?
2
3 Summary: There is no definitive way to limitglobal temperature rise to 1.5°C above pre-industrial
4 levels. This Special Report identifies two main conceptual pathways to illustrate different
5 interpretations. One stabilizes global temperature at, or just belaw, 1.5°C.Another sees global
6 temperature temporarily exceed 1.5°C before coming back dawn. Countries'pledges to reduce their
7 emissions are currently not in line with limiting global warming to 1.5°C.
8
9 Scientists use computer models to simulate the emissions of greenhouse gases that would be consistent
10 with different levels of warming. The different possibilities are often referred to as `greenhouse gas
11 emission pathways'. There is no single, definitive pathway to limiting warxning to 1.5°C.
12
13 This IPCC special report identifies two main pathways that explore global warming of 1.5°C. The first
14 involves global temperature stabilizing at or below before 1.5°C above pre-industrial levels. The
15 second pathway sees warming exceed 1.5°C around mid-century,remain above 1.5°C for a maximum
16 duration of a few decades, and return to below 1.5°C before 2100. The latter is often referred to as an
17 `overshoot' pathway. Any alternative situation in which global temperature continues to rise,
18 exceeding 1.5°C perxnanently until the end of the 21st century, is not considered to be a 1.5°C
19 pathway.
20
21 The two types of pathway have different implications for greenhouse gas emissions, as well as for
22 climate change impacts and for achieving sustainable development. For example,the larger and longer
23 an `overshooY, the greater the reliance on practices ar technologies that remove COZ from the
24 atmosphere, on top of reducing the sources of emissions (mitigation). Such ideas for COz removal have
25 not been proven to wark at scale and,therefore, run the risk of being less practical, effective or
26 economical than assumed. There is also the risk that the use of COZ removal techniques ends up
27 competing for land and water, and if these trade-offs are not appropriately managed, they can
28 adversely affect sustainable development. Additionally, a larger and longer overshoot increases the
29 risk for irreversible climate impacts, such as the onset of the collapse of polar ice shelves and
30 accelerated sea level rise.
31
32 Countries that formally accept or `ratify' the Paris Agreement submit pledges for how they intend to
33 address climate change. Unique to each country,these pledges are known as Nationally Determined
34 Contributions (NDCs). Different groups of researchers around the world have analysed the combined
35 effect of adding up all the NDCs. Such analyses show that current pledges are not on track to limit
36 global warming to 1.5°C above pre-industrial levels. If current pledges for 2030 are achieved but no
37 more,researchers find very few (if any)ways to reduce emissions after 2030 sufficiently quickly to
38 limit warxning to 1.5°C. This, in turn, suggests that with the national pledges as they stand,warxning
39 would exceed 1.5°C, at least for a period of time, and practices and technologies that remove COz
40 from the atmosphere at a global scale would be required to return warxning to 1.5°C at a later date.
41
42 A world that is consistent with holding warming to 1.5°C would see greenhouse gas emissions rapidly
43 decline in the coming decade, with strong international cooperation and a scaling up of countries'
44 combined ambition beyond current NDCs. In contrast, delayed action, limited international
45 cooperation, and weak or fragmented policies that lead to stagnating or increasing greenhouse gas
46 emissions would put the possibility of limiting global temperature rise to 1.5°C above pre-industrial
47 levels out of reach.
48
FAQ-6 Total pages: 23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
FAQ2.1:Conceptual pathways that limit global warming to 1.5°C
Two main pathways illustrate different interpretations for limiting global warming to 1.5°C.
The consequences will be different depending on the pathway
Global temperature stabilises at or Global temperature temporarily exceeds
below 1.5°C above preindustrial levels 1.5°C before returning later in the century
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3 FAQ2.1,Figure 1: Two main pathways for limiting global temperature rise to 1.5°C above pre-
4 industrial levels are discussed in this Special Report. These are: stabilizing global temperature at, or
5 just below, 1.5°C(left) and global temperature temporarily exceeding 1.5°C before coming back down
6 later in the century (right). Temperatures shown are relative to pre-industrial but pathways are
7 illustrative only,demonstrating conceptual not quantitative characteristics.
8
FAQ-7 Total pages:23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
1 FAQ 2.2: What Do Energy Supply and Demand Have to do with Limiting Warming to 1.5°C?
2
3 Summary:Limiting global warming to 1.5°C above pre-industrial levels would reguire major
4 reductions in greenhouse gas emissions in all sectors. But different sectors are not independent of
5 each other, and making changes in one can have implications for another. For example, if we as a
6 society use a lot of energy, then this could mean we have less flexibility in the choice ofmitigation
7 options available to limitwarming to 1.5°C. Ifwe use less energy, the choice ofpossible actions is
8 greater—for example, we could be less reliant on technologies that remove carbon dioxide (COZ)
9 from the atmosphere.
10
11 To stabilize global temperature at any level, `neY COZ emissions would need to be reduced to zero.
12 This means the amount of COZ entering the atmosphere must equal the amount that is removed.
13 Achieving a balance between COZ `sources' and `sinks' is often referred to as `net zerd emissions or
14 `carbon neutrality'. The implication of net zero emissions is that the concentration of COz in the
15 atmosphere would slowly decline over time until a new equilibrium is reached, as COZ emissions from
16 human activity are redistributed and taken up by the oceans and the land biosphere. This would lead to
17 a near-constant global temperature over many centuries.
18
19 Warming will not be limited to 1.5°C or 2°C unless transforxnations in a number of areas achieve the
20 required greenhouse gas emissions reductions. Emissions would need to decline rapidly across all of
21 society's main sectors, including buildings, industry, transport, energy, and agriculture,forestry and
22 other land use(AFOLi�. Actions that can reduce emissions include,for example,phasing out coal in
23 the energy sector, increasing the amount of energy produced from renewable sources, electrifying
24 transport, and reducing the `carbon footprinY of the food we consume.
25
26 The above are examples of`supply-side' actions. Broadly speaking,these are actions that can reduce
27 greenhouse gas emissions through the use of low-carbon solutions. A different type of action can
28 reduce how much energy human society uses,while still ensuring increasing levels of development
29 and well-being. Known as `demand-side' actions,this category includes improving energy efficiency
30 in buildings and reducing consumption of energy- and greenhouse-gas intensive products through
31 behavioural and lifestyle changes,for example. Demand- and supply-side measures are not an either-
32 or question,they work in parallel with each other. But emphasis can be given to one or the other.
33
34 Making changes in one sector can have consequences for another, as they are not independent of each
35 other. In other words, the choices that we make now as a society in one sector can either restrict or
36 expand our options later on. For example, a high demand for energy could mean we would need to
37 deploy almost all known options to reduce emissions in order to limit global temperabxre rise to 1.5°C
38 above pre-industrial levels,with the potential for adverse side-effects. In particular, a pathway with
39 high energy demand would increase our reliance on practices and technologies that remove COz from
40 the atmosphere. As of yet, such techniques have not been proven to wark on a large scale and,
41 depending on how they are implemented, could compete for land and water. By leading to lower
42 overall energy demand, effective demand-side measures could allow for greater flexibility in how we
43 structure our energy system. However, demand-side measures are not easy to implement and barriers
44 have prevented the most efficient practices being used in the past
45
FAQ-8 Total pages: 23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
FAQ22: Energy demand and supply in 7.5°C world
Lower energy demand could allow for greater Flexibility in how we strucNre our energy system.
allows more choice With ,there is
about which low-carbon energy supply less Flexibility as virtually all available
options to use to limit warming to 1.5°C. options would need to be considered.
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supply opt ons' supply opt ons' supply opt ons'
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1
2 FAQ2.2, Figure 1: Having a lower energy demand inereases the flexibility in choosing options for
3 supplying energy. A larger energy demand means many more low carbon energy supply options
4 would need to be used.
5
FAQ-9 Total pages: 23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
1 FAQ 3.1: What are the Impacts of LS°C and 2°C of Warming?
2
3 Summary: The impacts of climate change are being felt in every inhabited continent and in the
4 oceans. Hawever, they are not spread uniformly across the globe, and different parts of the world
5 experience impacts differently.An average warming of I.5°C across the whole globe raises the risk of
6 heatwaves and heavy rainfall events, amongst many other potential impacts. Limiting warming to
7 1.5°C rather than 2°C can help reduce these risks, but the impacts the world experiences will depend
8 on the specific greenhouse gas emissions `pathway'taken. The consequences of temporarily
9 overshooting 1.5°C ofwarming and returning to this level later in the century,for e�mple, could be
10 larger than if temperature stabilizes below 1.5°C. The size and duration of an overshoot will also
11 affect future impacts.
12
13 Human activity has warmed the world by about 1°C since pre-industrial times, and the impacts of this
14 warming have already been felt in many parts of the world. This estimate of the increase in global
15 temperature is the average of many thousands of temperature measurements taken over the world's
16 land and oceans. Temperatures are not changing at the same speed everywhere,however: warming is
17 strongest on continents and is particularly strong in the Arctic in the cold season and in mid-latibxde
18 regions in the warm season. This is due to self-amplifying mechanisms,for instance due to snow and
19 ice melt reducing the reflectivity of solar radiation at the surface, or soil drying leading to less
20 evaporative cooling in the interior of continents. This means that some parts of the world have already
21 experienced temperatures greater than 1.5°C above pre-industrial levels.
22
23 Extra warming on top of the approximately 1°C we have seen so far would amplify the risks and
24 associated impacts,with implications far the world and its inhabitants. This would be the case even if
25 the global warxning is held at 1.5°C,just half a degree above where we are now, and would be further
26 amplified at 2°C of global warming. Reaching 2°C instead of 1.5°C of global warming would lead to
27 substantial warxning of extreme hot days in all land regions. It would also lead to an increase in heavy
28 rainfall events in some regions,particularly in the high latitudes of the Northern Hemisphere,
29 potentially raising the risk of flooding. In addition, some regions, such as the Mediterranean, are
30 projected to become drier at 2°C versus 1.5°C of global warming. The impacts of any additional
31 warming would also include stronger melting of ice sheets and glaciers, as well as increased sea level
32 rise,which would continue long after the stabilization of ahnospheric COZ concentrations.
33
34 Change in climate means and extremes have knock-on effects far the societies and ecosystems living
35 on the planet. Climate change is projected to be a poverly multiplier, which means that its impacts are
36 expected to make the poor poorer and the total number of people living in poverly greater. The 0.5°C
37 rise in global temperatures that we have experienced in the past 50 years has contributed to shifts in
38 the distribution of plant and animal species, decreases in crop yields and more frequent wildfires.
39 Similar changes can be expected with further rises in global temperature.
40
41 Essentially,the lower the rise in global temperabxre above pre-industrial levels,the lower the risks to
42 human societies and natural ecosystems. Put another way, limiting warxning to 1.5°C can be
43 understood in terxns of`avoided impacts' compared to higher levels of warxning. Many of the impacts
44 of climate change assessed in this report have lower associated risks at 1.5°C compared to 2°C.
45
46 Thermal expansion of the oceans,resulting from delayed ocean mixing,means sea level will continue
47 to rise even if global temperature is limited to 1.5°C,but this rise would be lower than in a 2°C
48 warmer world. Ocean acidification,the process by which excess COZ dissolves into oceans and makes
49 them more acidic, is expected to be less damaging in a world where COZ emissions are reduced and
50 warming is stabilized at 1.5°C compared to 2°C. The persistence of coral reefs is greater in a 1.5°C
51 world than that of a 2°C world,too.
52
FAQ-10 Total pages: 23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
1 The impacts of climate change that we experience in future will be affected by factors other than the
2 change in temperature. The consequences of 1.5°C of warming will additionally depend on the
3 specific greenhouse gas emissions `pathway' that is followed and the extent to which adaptation can
4 reduce vulnerability. This IPCC Special Report uses a number of`pathways' to explore different
5 possibilities for limiting global warming to 1.5°C above pre-industrial levels. One type of pathway
6 sees global temperature stabilize at, or just below, 1.5°C. Another sees global temperature temporarily
7 exceed 1.5°C before declining later in the cenbxry (known as an `overshooY pathway).
8
9 Such pathways would have different associated impacts, so it is important to distinguish between them
10 for planning adaptation and mitigation strategies. For example, impacts from an overshoot pathway
11 could be larger than impacts from a stabilization pathway. The size and duration of an overshoot
12 would also have consequences far the impacts the world experiences. For instance, pathways that
13 overshoot 1.5°C run a greater risk of passing through `tipping points', thresholds beyond which certain
14 impacts can no longer be avoided even if temperatures are brought back down later on. The collapse of
15 the Greenland and Antarotic ice sheets on the timescale of centuries and millennia is one example of a
16 tipping point
17
FAQ3.1:Impact of 1.5°C and 2.0°C global warming
TempereNre rise is not uniform across the wodd.Some regions will experience grealer increases in hol days
and decreases in cold nights than others
+7.5°C:Change in averege tempereture of holtest days +y,0°C:Change in averege tempereture of hottest days
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19 FAQ 3.1, Figure L• Temperature change is not uniform across the globe. Projected changes are shown
20 far the average temperature of the annual hottest day(top) and the annual coldest
21 night(bottom)with 1.5°C of global warming(left) and 2°C of global warming
22 (right) compared to pre-industrial levels.
23
FAQ-11 Total pages: 23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
1 FAQ 4.1: What Transitions Could Enable Limiting Global Warming to LS°C?
2
3 Summary:In order to limit warming to 1.5°C above pre-industrial levels, the world would need to
4 transform in a number of complex and connected ways. While transitions tawards lawer greenhouse
5 gas emissions are underway in some cities, regions, countries, businesses and communities, there are
6 few that are currently consistent with limiting warming to 1.5°C.Meeting this challenge would reguire
7 a rapid escalation in the current scale and pace of change,particularly in the coming decades. There
8 are many factors that affect the feasibility of different adaptation and mitigation options that could
9 help limit warming to 1.5°C and with adapting to the conseguences.
10 There are actions across all sectors that can substantially reduce greenhouse gas emissions. This
11 Special Report assesses energy, land and ecosystems,urban and infrastructure, and industry in
12 developed and developing nations to see how they would need to be transforxned to limit warxning to
13 1.5°C. Examples of actions include shifting to low- or zero-emission power generation, such as
14 renewables; changing food systems, such as diet changes away from land-intensive animal products;
15 electrifying transpart and developing `green infrastructure', such as building green roofs, or improving
16 energy efficiency by smart urban planning, which will change the layout of many cities.
17 Because these different actions are connected, a `whole systems' approach would be needed for the
18 type of transforxnations that could limit warming to 1.5°C. This means that all relevant companies,
19 industries and stakeholders would need to be involved to increase the suppart and chance of successful
20 implementation. As an illustration, the deployment of low-emission technology(e.g.,renewable
21 energy projects or a bio-based chemical plants)would depend upon economic conditions (e.g.,
22 employment generation or capacity to mobilize inveshnent),but also on sociaUculbxral conditions
23 (e.g., awareness and acceptability) and instibxtional conditions (e.g.,political support and
24 understanding).
25 To limit warming to 1.5°C,mitigation would have to be large-scale and rapid. Transitions can be
26 transforxnative or incremental, and they often, but not always, go hand in hand. Transformative change
27 can arise from growth in demand for a new product or market, such that it displaces an existing one.
28 This is sometimes called `disruptive innovation'. For example, high demand for LED lighting is now
29 making more energy-intensive, incandescent lighting near-obsolete,with the suppart of policy action
30 that spurred rapid industry innovation. Similarly, smart phones have become global in use within ten
31 years. But electric cars,which were released around the same time,have not been adopted so quickly
32 because the bigger, more connected transpart and energy systems are harder to change. Renewable
33 energy, especially solar and wind, is considered to be disruptive by some as it is rapidly being adopted
34 and is transitioning faster than predicted. But its demand is not yet uniform. Urban systems that are
35 moving towards transforxnation are coupling solar and wind with battery storage and electric vehicles
36 in a more incremental transition, though this would still require changes in regulations,tax incentives,
37 new standards, demonstration projects and education programmes to enable markets far this system to
38 work.
39 Transitional changes are already underway in many systems, but limiting warming to 1.5°C would
40 require a rapid escalation in the scale and pace of transition,particularly in the next 10-20 years.
41 While limiting warming to 1.5°C would involve many of the same types of transitions as limiting
42 warming to 2°C, the pace of change would need to be much faster. While the pace of change that
43 would be required to limit warxning to 1.5°C can be found in the past,there is no historical precedent
44 far the scale of the necessary transitions, in particular in a socially and economically sustainable way.
45 Resolving such speed and scale issues would require people's support,publio-sector interventions and
46 private-sector cooperation.
FAQ-12 Total pages: 23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
1 Different types of transitions carry with them different associated costs and requirements for
2 institutional or governmental support. Some are also easier to scale up than others, and some need
3 more government support than others. Transitions between, and within,these systems are connected
4 and none would be sufficient on its own to limit warming to 1.5°C.
5 The `feasibility' of adaptation and mitigation options or actions within each system that together can
6 limit warming to 1.5°C within the context of sustainable development and effarts to eradicate poverty
7 requires careful consideration of multiple different factors. These factors include: (i)whether
8 sufficient natural systems and resources are available to support the various options far transitioning
9 (known as environmental feasibility); (ii)the degree to which the required technologies are developed
10 and available(known as technological feasibility); (iii)the economic conditions and implications
11 (known as economic feasibility); (iv)what are the implications for human behaviour and health
12 (known as social/cultural feasibility); and(v)what type of institutional support would be needed, such
13 as governance, institutional capacity and political support(known as institutional feasibility). An
14 additional factor(vi—known as the geophysical feasibility) addresses the capacity of physical systems
15 to carry the option, for example,whether it is geophysically possible to implement large-scale
16 afforestationconsistentwithl.5°C.
17 Promoting enabling conditions, such as finance, innovation and behaviour change,would reduce
18 barriers to the options, make the required speed and scale of the system transitions more likely, and
19 therefore would increase the overall feasibility limiting warming to 1.5°C.
FAQ4.1: The different feasibility dimensions towards limiting warming to 1.5°C
Assessing the feasibility of different adaptation and mitigation options/actions requires consideration across six dimensions.
Environmental Technological
feasibility feasibility
O �
Geophysical 1� $ Economic
feasibility � � feasibility
Institutional Social/cultural feasi-
feasibility bility
20
21
22 FAQ4.1, Figure L• The different dimensions to consider when assessing the `feasibility' of adaptation
23 and mitigation options or actions within each system that can help to limit warxning to 1.5°C. These
FAQ-13 Total pages: 23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
1 are: (i)the environxnental feasibility; (ii)the technological feasibility; (iii)the economic feasibility;
2 (iv)the social/culbxral feasibility; (v)the instibxtional feasibility; and(vi)the geophysical feasibility.
3
FAQ-14 Total pages: 23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
1 FAQ 4.2: What are Carbon Dioxide Removal and Negative Emissions?
2
3 Summary: Carbon dioxide removal(CDR) refers to the process of removing COz from the
4 atmosphere. Since this is the opposite of emissions,practices or technologies that remove COz are
5 often described as achieving `negative emissions'. The process is sometimes referred to more broadly
6 as greenhouse gas removal if it involves removing gases other than COz. There are two main types of
7 CDR: either enhancing existing natural processes that remove carbon from the atmosphere (e.g., by
8 increasing its uptake by trees, soil, or other `carbon sinks) or using chemical processes to,for
9 example, capture COz directly from the ambient air and store it elsewhere (e.g., underground).All
10 CDR methods are at different stages of development and some are more conceptual than others, as
11 they have not been tested at scale.
12 Limiting warming to 1.5°C above pre-industrial levels would require unprecedented rates of
13 transforxnation in many areas, including in the energy and industrial sectors, for example.
14 Conceptually, it is possible that techniques to draw COz out ofthe atmosphere(lrnown as carbon
15 dioxide removal, or CDR) could contribute to limiting warxning to 1.5°C. One use of CDR could be to
16 compensate for greenhouse gas emissions from sectors that cannot completely decarbonize, or which
17 may take a long time to do so.
18 If global temperature temporarily overshoots 1.5°C, CDR would be required to reduce the atmospheric
19 concentration of COZ to bring global temperabxre back down. To achieve this temperabxre reduction,
20 the amount of COz drawn out of the ahnosphere would need to be greater than the amount entering the
21 atmosphere,resulting in `net negative emissions'. This would involve a greater amount of CDR than
22 stabilizing atmospheric COz concentration—and,therefore, global temperature—at a certain level. The
23 larger and longer an overshoot, the greater the reliance on practices that remove COZ from the
24 atmosphere.
25 There are a number of CDR methods, each with different potentials for achieving negative emissions,
26 as well as different associated costs and side effects. They are also at differing levels of development,
27 with some more conceptual than others. One example of a CDR method in the demonstration phase is
28 a process known as bioenergy with carbon capture and storage(BECCS), in which ahnospheric COz is
29 absorbed by plants and trees as they grow, and then the plant material(biomass) is burned to produce
30 bioenergy. The COz released in the production of bioenergy is captured before it reaches the
31 atmosphere and stored in geological forxnations deep underground on very long timescales. Since the
32 plants absorb COz as they grow and the process does not emit COz,the overall effect can be to reduce
33 atmospheric COz.
34 Afforestation(planting new trees) and reforestation(replanting trees where they previously existed)
35 are also considered forms of CDR because they enhance natural COZ `sinks'. Another category of
36 CDR techniques uses chemical processes to capture COZ from the air and store it away on very long
37 timescales. In a process known as direct air carbon capture and storage(DACCS), COz is extracted
38 directly from the air and stored in geological forxnations deep underground. Converting waste plant
39 material into a charcoal-like substance called biochar and burying it in soil can also be used to store
40 carbon away from the atmosphere for decades to centuries.
41 There can be beneficial side effects of some types of CDR, other than removing COZ from the
42 atmosphere. For example, restoring forests or mangroves can enhance biodiversity and protect against
43 flooding and storxns. But there could also be risks involved with some CDR methods. For example,
44 deploying BECCS at large scale would require a large amount of land to cultivate the biomass
45 required for bioenergy. This could have consequences for sustainable development if the use of land
46 competes with producing food to support a growing population, biodiversity conservation or land
47 rights. There are also other considerations. For example, there are uncertainties about how much it
FAQ-15 Total pages: 23
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1 would cost to deploy DACCS as a CDR technique, given that removing COz from the air requires
2 considerable energy.
FAQ42: Carbon dioxide removal and negative emissions
Examples of some CDR/negative emissions techniques and practices
Bioenergy with Carbon Capture Afforestation and
and Storage(BECCS) re-forestation
COs
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4 FAQ4.2, Figure L• Carbon dioxide removal (CDR)refers to the process of removing COz from the
5 atmosphere. There are a number of CDR techniques, each with different potential for achieving
6 `negative emissions', as well as different associated costs and side effects.
7
FAQ-16 Total pages: 23
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1 FAQ 4.3: Why is Adaptation Important in a LS°C-Warmer World?
2 Summary:Adaptation is the process of adjusting to current or expected changes in climate and its
3 effects. Even though climate change is a global problem, its impacts are experienced differently across
4 the world. This means that responses are often specific to the local context, and so people in different
5 regions are adapting in different ways.A rise in global temperature from the current 1°C above pre-
6 industrial levels to 1.5°C, and beyond, increases the need for adaptation. Therefore, stabilizing global
7 temperatures at 1.5°C above pre-industrial levels would reguire a smaller adaptation effort than at
8 2°C. Despite many successful examples around the world,progress in adaptation is, in many regions,
9 in its infancy and unevenly distributed globally.
10 Adaptation refers to the process of adjushnent to actual or expected changes in climate and its effects.
11 Since different parts of the world are experiencing the impacts of climate change differently, there is
12 similar diversity in how people in a given region are adapting to those impacts.
13 The world is already experiencing the impacts from 1°C of global warxning above pre-industrial
14 levels, and there are many examples of adaptation to impacts associated with this warxning. Examples
15 of adaptation efforts taking place around the world include investing in flood defences such as
16 building sea walls or restoring mangroves, efforts to guide development away from high risk areas,
17 modifying crops to avoid yield reductions, and using social learning(social interactions that changes
18 understanding on the community level)to modify agricultural practices, amongst many others.
19 Adaptation also involves building capacity to respond better to climate change impacts, including
20 making governance more flexible and strengthening financing mechanisms, such as by providing
21 different types of insurance.
22 In general, an increase in global temperature from present day to 1.5°C or 2°C(or higher) above pre-
23 industrial temperatures would increase the need for adaptation. Stabilising global temperabxre increase
24 at 1.5°C would require a smaller adaptation effort than for 2°C.
25 Since adaptation is still in early stages in many regions,there are questions about the capacity of
26 wlnerable communities to cope with any amount of further warming. Successful adaptation can be
27 supported at the national and sub-national levels, with national governments playing an important role
28 in coordination,planning, determining policy priorities, and distributing resources and suppart.
29 However, given that the need for adaptation can be very different from one community to the next,the
30 kinds of ineasures that can successfully reduce climate risks will also depend heavily on the local
31 context.
32 When done successfully, adaptation can allow individuals to adjust to the impacts of climate change in
33 ways that minimize negative consequences and to maintain their livelihoods. This could involve, for
34 example, a farmer switching to drought-tolerant crops to deal with increasing occurrences of
35 heatwaves. In some cases,however,the impacts of climate change could result in entire systems
36 changing significantly, such as moving to an entirely new agricultural system in areas where the
37 climate is no longer suitable for current practices. Constructing sea walls to stop flooding due to sea
38 level rise from climate change is another example of adaptation, but developing city planning to
39 change how flood water is managed throughout the city would be an example of transformational
40 adaptation. These actions require significantly more institutional, structural, and financial support.
41 While this kind of transforxnational adaptation would not be needed everywhere in a 1.5°C world, the
42 scale of change needed would be challenging to implement, as it requires additional support, such as
43 through financial assistance and behavioural change. Few empirical examples exist to date.
44 Examples from around the world show that adaptation is an iterative process. Adaptation pathways
45 describe how communities can make decisions about adaptation in an ongoing and flexible way. Such
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1 pathways allow for pausing, evaluating the outcomes of specific adaptation actions, and modifying the
2 strategy as appropriate. Due to their flexible nature, adaptation pathways can help to identify the most
3 effective ways to minimise the impacts of present and future climate change for a given local conteat.
4 This is important since adaptation can sometimes exacerbate vulnerabilities and existing inequalities if
5 poorly designed. The unintended negative consequences of adaptation that can sometimes occur are
6 known as `maladaptation'. Maladaptation can be seen if a particular adaptation option has negative
7 consequences for some (e.g., rainwater harvesting upstream might reduce water availability
8 downstream) or if an adaptation intervention in the present has trade-offs in the future (e.g.,
9 desalination plants may improve water availability in the present but have large energy demands over
10 time).
11 While adaptation is important to reduce the negative impacts from climate change, adaptation
12 measures on their own are not enough to prevent climate change impacts entirely. The more global
13 temperature rises,the more frequent, severe, and erratic the impacts will be, and adaptation may not
14 protect against all risks. Examples of where limits may be reached include substantial loss of coral
15 reefs, massive range losses far terrestrial species, more human deaths from eatreme heat, and losses of
16 coastal-dependent livelihoods in low lying islands and coasts.
FAQ4.3:Adaptation in a warming world
Adapting to further warming requires action at national&sub-national levels and can mean different things to different people
in different contexts
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18 FAQ4.3, Figure 1: Examples of adaptation and transformational adaptation. Adapting to further
19 warming requires action at national and sub-national levels and can mean different things to different
20 people in different conteats. While transformational adaptation would not be needed everywhere in a
21 world limited to 1.5°C warming,the scale of change needed would be challenging to implement.
22
23
24
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1 FAQ 5.1: What Are the Connections between Sustainable Development and Limiting Global
2 Warxning to 1.5°C above Pre-Industrial Levels?
3
4 Summary: Sustainable development seeks to meet the needs of people living today without
5 compromising the needs offuture generations, while balancing social, economic and environmental
6 considerations. The 17 UNSustainable Development Goals (SDGs) include targets for eradicating
7 poverty; ensuring health, energy and food security; reducing inequality;protecting ecosystems;
8 pursuing sustainable cities and economies; and a goal for climate action (SDG13). Climate change
9 affects the ability to achieve sustainable developmentgoals, and limiting warming to 1.5°C will help
10 meet some sustainable development targets. Pursuing sustainable development will influence
11 emissions, impacts and vulnerabilities. Responses to climate change in the form of adaptation and
12 mitigation will also interactwith sustainable developmentwith positive effects, knawn as synergies, or
13 negative effects, known as trade-offs. Responses to climate change can be planned to maximize
14 synergies and limit trade-offs with sustainable development.
15
16 For more than 25 years, the United Nations (LJN) and other international organizations have embraced
17 the concept of sustainable development to promote well-being and meet the needs of today's
18 population without compromising the needs of future generations. This concept spans economic,
19 social and environxnental objectives including poverty and hunger alleviation, equitable economic
20 growth, access to resources, and the protection of water, air and ecosystems. Between 1990 and 2015,
21 the iJN monitored a set of eight Millennium Development Goals (MDGs). They reported progress in
22 reducing poverty, easing hunger and child mortality, and improving access to clean water and
23 sanitation. But with millions remaining in poor health, living in poverty and facing serious problems
24 associated with climate change, pollution and land-use change,the iJN decided that more needed to be
25 done. In 2015,the iJN Sustainable Development Goals (SDGs)were endorsed as part of the 2030
26 Agenda for Sustainable Development. The 17 SDGs (Figure FAQ 5.1) apply to all countries and have
27 a timeline for success by 2030. The SDGs seek to eliminate extreme poverty and hunger; ensure
28 health, education,peace, safe water and clean energy for all;promote inclusive and sustainable
29 consumption, cities, infrastructure and economic growth;reduce inequality including gender
30 inequality; combat climate change and protect oceans and terrestrial ecosystems.
31
32 Climate change and sustainable development are fundamentally connected. Previous IPCC reports
33 found that climate change can undermine sustainable development, and that well-designed mitigation
34 and adaptation responses can support poverty alleviation,food security, healthy ecosystems, equality
35 and other dimensions of sustainable development. Limiting global warxning to 1.5°C would require
36 mitigation actions and adaptation measures to be taken at all levels. These adaptation and mitigation
37 actions would include reducing emissions and increasing resilience through technology and
38 infrastructure choices, as well as changing behaviour and policy. These actions can interact with
39 sustainable development objectives in positive ways that strengthen sustainable development, known
40 as synergies. Or they can interact in negative ways,where sustainable development is hindered or
41 reversed, known as trade-offs.
42
43 An example of a synergy is sustainable forest management, which can prevent emissions from
44 deforestation and take up carbon to reduce warming at reasonable cost. It can work synergistically
45 with other dimensions of sustainable development by providing food(SDG 2) and clean water(SDG
46 � and protecting ecosystems (SDG 15). Other examples of synergies are when climate adaptation
47 measures, such as coastal or agricultural projects, empower women and benefit local incomes,health
48 and ecosystems.
49
50 An example of a trade-off can occur if ambitious climate change mitigation compatible with 1.5°C
51 changes land use in ways that have negative impacts on sustainable development. An example could
52 be turning natural forests, agricultural areas, or land under indigenous or local ownership to
53 plantations for bioenergy production. If not managed carefully, such changes could underxnine
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1 dimensions of sustainable development by threatening food and water security, creating conflict over
2 land rights and causing biodiversity loss. Another trade-off could occur for some countries, assets,
3 warkers and infrastructure already in place if a switch is made from fossil fuels to other energy
4 sources without adequate planning for such a transition. Trade-offs can be minimized if effectively
5 managed, as when care is taken to improve bioenergy crop yields to reduce harxnful land-use change
6 or where workers are retrained for employment in lower carbon sectors.
7
8 Limiting temperabxres to 1.5°C can make it much easier to achieve the SDGs,but it is also possible
9 that pursuing the SDGs could result in trade-offs with efforts to limit climate change. There are trade-
10 offs when people escaping from poverty and hunger consume more energy or land and thus increase
11 emissions, or if goals for economic growth and industrialization increase fossil fuel consumption and
12 greenhouse gas emissions. Conversely, efforts to reduce poverty and gender inequalities and to
13 enhance food,health and water security can reduce wlnerability to climate change. Other synergies
14 can occur when coastal and ocean ecosystem protection reduces the impacts of climate change on
15 these systems. The sustainable development goal of affordable and clean energy(SDG 7) specifically
16 targets access to renewable energy and energy efficiency,which are important to ambitious mitigation
17 and limiting warxning to 1.5°C.
18
19 The link between sustainable development and limiting global warxning to 1.5°C is recognized by the
20 SDG for climate action(SDG 13), which seeks to combat climate change and its impacts while
21 acknowledging that the United Nations Framewark Convention on Climate Change(LJNFCCC) is the
22 primary international, intergovernxnental forum for negotiating the global response to climate change.
23
24 The challenge is to put in place sustainable development policies and actions that reduce deprivation,
25 alleviate poverty and ease ecosystem degradation while also lowering emissions,reducing climate
26 change impacts and facilitating adaptation. It is important to strengthen synergies and minimize trade-
27 offs when planning climate change adaptation and mitigation actions. Unfortunately, not all trade-offs
28 can be avoided or minimized,but careful planning and implementation can build the enabling
29 conditions for long-terxn sustainable development.
30
FAQ5.1: The United Nations Sustainable Development Goals (SDGs)
The link between sustainable development and limiting global warming l0 1.5°C is recognised by ihe Sustainable Development Goal
for climate action(SDG 13)
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32 FAQ 5.1, Figure L• Climate change action is one of the United Nations Sustainable Development
33 Goals (SDGs) and is connected to sustainable development more broadly. Actions to reduce climate
FAQ-20 Total pages: 23
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1 risk can interact with other sustainable development objectives in positive ways (synergies)and
2 negative ways (trade-offs).
3
4
FAQ-21 Total pages: 23
Pre-trickle back version Frequently Asked Questions IPCC SR1.5
1 FAQ 5.2: What are the Pathways to Achieving Poverty Reduction and Reducing Inequalities
2 While Reaching the LS°C World?
3
4 Summary: There are ways to limitglobal warming to 1.5°C above pre-industrial levels. Of the
5 pathways that exist, some simultaneously achieve sustainable development. They entail a mix of
6 measures that lawer emissions and reduce the impacts of climate change, while contributing to
7 poverty eradication and reducing inequalities. Which pathways are possible and desirable will differ
8 between and within regions and nations. This is due to the fact that development progress to date has
9 been uneven and climate-related risks are unevenly distributed. Flexible governance would be needed
10 to ensure that such pathways are inclusive,fair and equitable to avoid poor and disadvantaged
11 populations becoming worse off. Climate-resilient development pathways (CRDPs) offer possibilities
12 to achieve both equitable and law-carbon futures.
13
14 Issues of equity and fairness have long been central to climate change and sustainable development.
15 Equity, like equality, aims to promote justness and fairness for all. This is not necessarily the same as
16 treating everyone equally, since not everyone comes from the same starting point. Often used
17 interchangeably with fairness and justice, equity implies implementing different actions in different
18 places, all with a view to creating an equal world that is fair for all and where no one is left behind.
19
20 The Paris Agreement states that it`will be implemented to reflect equity... in the light of different
21 national circumstances' and calls far `rapid reductions' of greenhouse gases to be achieved `on the
22 basis of equity, and in the context of sustainable development and efforts to eradicate poverly'.
23 Similarly,the iJN SDGs include targets to reduce poverty and inequalities, and to ensure equitable and
24 affordable access to health,water and energy for all.
25
26 The principles of equity and fairness are important for considering pathways that limit warming to
27 1.5°C in a way that is liveable for every person and species. They recognize the uneven development
28 status between richer and poorer nations,the uneven distribution of climate impacts (including on
29 future generations) and the uneven capacity of different nations and people to respond to climate risks.
30 This is particularly true for those who are highly wlnerable to climate change, such as indigenous
31 communities in the Arctic,people whose livelihoods depend on agriculture or coastal and marine
32 ecosystems, and inhabitants of small island developing states. The poorest people will continue to
33 experience climate change through the loss of income and livelihood opportunities, hunger, adverse
34 health effects and displacement
35
36 Well-planned adaptation and mitigation measures are essential to avoid exacerbating inequalities or
37 creating new injustices. Pathways that are compatible with limiting warxning to 1.5°C and aligned with
38 the SDGs consider mitigation and adaptation options that reduce inequalities in terxns of who benefits,
39 who pays the costs and who is affected by possible negative consequences. Attention to equity ensures
40 that disadvantaged people can secure their livelihoods and live in dignity, and that those who
41 experience mitigation or adaptation costs have financial and technical support to enable fair
42 transitions.
43
44 CRDPs describe trajectories that pursue the dual goal of limiting warxning to 1.5°C while
45 strengthening sustainable development. This includes eradicating poverty as well as reducing
46 wlnerabilities and inequalities for regions, countries, communities, businesses and cities. These
47 trajectories entail a mix of adaptation and mitigation measures consistent with profound societal and
48 systems transforxnations. The goals are to meetthe shart-term SDGs, achieve longer-term sustainable
49 development,reduce emissions towards net zero around the middle of the century,build resilience and
50 enhance human capacities to adapt, all while paying close attention to equity and well-being for all.
51
52 The characteristics of CRDPs will differ across communities and nations, and will be based on
53 deliberations with a diverse range of people, including those most affected by climate change and by
FAQ-22 Total pages: 23
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1 possible routes towards transforxnation. For this reason, there are no standard methods for designing
2 CRDPs or for monitoring their progress towards climate-resilient futures. However, examples from
3 around the world demonstrate that flexible and inclusive governance structures and broad participation
4 often help support iterative decision-making, continuous learning and experimentation. Such inclusive
5 processes can also help to overcome weak institutional arrangements and power structures that may
6 further exacerbate inequalities.
7
FAQ52: Climate-resilient development pathways
Decision-making lhal achieves the United Nalion Sustainable Development Goals(SDGs),lowers greenhouse gas emissions,
limits global warming,and enhances adaplatioq could help lead to a dimate-resilient world
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9 FAQ 5.2, Figure L• Climate-resilient development pathways (CRDPs)describe trajectories that
10 pursue the dual goals of limiting warxning to 1.5°C while strengthening sustainable development.
11 Decision-making that achieves the SDGs, lowers greenhouse gas emissions and limits global warnung
12 could help lead to a climate-resilient world, within the context of enhancing adaptation.
13
14 Ambitious actions already underway around the world can offer insight into CRDPs for limiting
15 warnung to 1.5°C. For example, some countries have adopted clean energy and sustainable transport
16 while creating environxnentally friendly jobs and supporting social welfare programmes to reduce
17 domestic poverty. Other examples teach us about different ways to promote development through
18 practices inspired by community values. For instance,Buen Pivir, a Latin American concept based on
19 indigenous ideas of communities living in harxnony with nature, is aligned with peace; diversity;
20 solidarity; rights to education, health, and safe food, water, and energy; and well-being and justice for
21 a1L The Transition Movement, with origins in Europe,promotes equitable and resilient communities
22 through low-carbon living, food self-sufficiency and citizen science. Such examples indicate that
23 pathways that reduce poverty and inequalities while limiting warxning to 1.5°C are possible and that
24 they can provide guidance on pathways towards socially desirable, equitable and low-carbon futures.
25
26
27
FAQ-23 Total pages: 23
IpCC
INTEPGOVERNMENTAL PANEL ON climate chanQe
Global Warming of 1 . 5 ° C
An IPCC Special fteport on the impacts of global warming of 1 .5°C
above pre-industrial levels and related global greenhouse gas emission pathways,
in the context oF strengthening the global response to the threat of climate change,
sustainable development, and efforts to eradicate poverty
� ' �
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WG I WG II WG III � :_'�� �
WMO UNEP
Global warming of 1 . 5°C
An IPCC Special Report on the impacts of global warming of 1.5°C
above pre-industrial levels and related global greenhouse gas emission pathways,
in the context of strengthening the global response to the threat of climate change,
sustainable development, and efforts to eradicate poverty
Summary for Policymakers
Edited by
Valerie Masson-Delmotte Panmao Zhai
CaChair Working Group I CaChair Working Group I
Hans-Otto Portner Debra Roberts
CaChairWorking Group II CaChairWorking Group II
Jim Skea Priyadarshi R. Shukla
CaChairWorking Group III CaChairWorking Group III
Anna Pirani Wilfran Moufouma-Okia Clotilde Pean
Head of WGI TSU Head of Science Head of Operations
Roz Pidcock Sarah Connors J. B. Robin Matthews
Head of Communication Science Officer Science Officer
Yang Chen Xiao Zhou Melissa I. Gomis
Science Officer Science Assistant Graphics Officer
Elisabeth Lonnoy Tom Maycock Melinda Tignor Tim Waterfield
ProjectAssistant Science Editor Head ofWGIITSU IT Officer
Working Group I Technical Support Unit
kont cover layout:Nigel Haw[in
kont cover artwork:Time to Choose by Alisa Singer vwwv.environmentalgraphifi.org-O Intergovemmental Panel on Climate Change.
The artwork was inspired by a graphic from the SPM(Fgure SPM.1).
O 20181ntergovemmental Panel on(]imate Change.
Pnnted October 2018 by the IPCC,Switzedand.
Elec[ronic copies of this Summary for Policymakers are available from the IPCC website vwwv.ipcc.ch
ISBN 9 7 8-9 2-91 6 11 51-7
Summary for Policymakers
Summary for Policymakers
� Summary
for Policymakers
Drafting Authors:
Myles Allen (UK), Mustafa Babiker (Sudan), Yang Chen (China), Heleen de Coninck
(Netherlands/EU), Sarah Connors (UK), Renee van Diemen (Netherlands), Opha Pauline
Dube (Botswana), Kristie L. Ebi (USA), Francois Engelbrecht (South Africa), Marion Ferrat
(UK/France), James Ford (UK/Canada), Piers Forster (UK), Sabine Fuss (Germany), Tania
Guillen Bolanos(Germany/Nicaragua),Jordan Harold(UK),Ove Hoegh-Guldberg(Australia),
JeamCharles Hourcade (France), Daniel Huppmann (Austria), Daniela Jacob (Germany),
Kejun Jiang (China),Tom Gabriel Johansen (Norway), Mikiko Kainuma papan), Kiane de
Kleijne (Netherlands/EU), Elmar Kriegler (Germany), Debora Ley (Guatemala/Mexico),
Diana Liverman (USA), Natalie Mahowald (USA), Valerie Masson-Delmotte (France),
J. B. Robin Matthews (UK), Richard Millar (UK), Katja Mintenbeck (Germany), Angela
Morelli (Norway/Italy), Wilfran Moufouma-0kia (France/Congo), Luis Mundaca (Sweden/
Chile),Maike Nicolai (Germany),Chukwumerije Okereke(UK/Nigeria),Minal Pathak Qndia),
Anthony Payne(UK),Roz Pidcock(UK),Anna Pirani(Italy),Elvira Poloczanska(UK/Australia),
Hans-Otto Portner(Germany),Aromar Revi Qndia),Keywan Riahi(Austria),Debra C.Roberts
(South Africa), Joeri Rogelj (Austria/Belgium), Joyashree Roy (India), Sonia l. Seneviratne
(Switzerland), Priyadarshi R. Shukla (India), James Skea (UK), Raphael Slade (UK), Drew
Shindell (USA), Chandni Singh Qndia), William Solecki (USA), Linda Steg (Netherlands),
Michael Taylor (Jamaica), Petra Tschakert (Australia/Austria), Henri Waisman (France),
Rachel Warren (UK),Panmao Zhai (China),Kirsten Zickfeld (Canada).
This Summary for Policymakers should be cited as:
IPCC,2018:Summary for Policymakers.In:Global warming of 1.5°C An IPCC Special Report on the impac[s
ofglobal warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways,
in the context ofstrengthening the global response to the[hreatofdimate change,sustainable development,
and efforts to eradicate poverry�V.Masson-0elmotte,P.Zhai,H.0.Pbrtner,D.Roberts,1.Skea, P. R.Shukla,
A.Pirani,W.Moufouma-0kia,C Pean,R.Pidcock,S Connors,l.B.R.Matthews,Y Cheq X.Zhou,M.I.6omis,
E Lonnoy,T.Maycock,M.Tignor,T.Waterfield(eds.)].Wodd MeteorologicalOrganization,Geneva,Swi�edand,
31 pp.
3
Summary for Policymakers
Acknowledgements
We are very grateful for the expertise, rigour and dedication shown throughout by
the volunteer Coordinating Lead Authors and Lead Authors, working across scientific
disciplines in each chapter of the report, with essential help by the many Contributing
Authors. The Review Editors have played a critical role in assisting the author teams and
ensuring the integriry of the review process.We express our sincere appreciation to all the
expert and government reviewers.A special thanks goes to the Chapter Scientists of this
report who went above and beyond what was expected of them: Neville Ellis,Tania Guillen
Bolanos,Daniel Huppmann,Kiane de Kleijne,Richard Millar and Chandni Singh.
We would also like to thank the three Intergovernmental Panel on Climate Change QPCC)
Vice-Chairs Ko Barrett, Thelma Krug, and Youba Sokona as well as the members of the
WGI,WGII and WGIII Bureaux for their assistance,guidance, and wisdom throughout the
preparation of the Report: Amjad Abdulla, Edvin Aldrian, Carlo Carraro, Diriba Korecha
Dadi, Fatima Driouech, Andreas Fischlin, Gregory Flato, Jan Fuglestvedt, Mark Howden,
Nagmeldin G. E. Mahmoud,Carlos Mendez,Joy Jacqueline Pereira,Ramon Pichs-Madruga,
Andy Reisinger, Roberto Sanchez Rodriguez, Sergey Semenov, Muhammad I. Tariq, Diana
Urge-Vorsatz,Carolina Vera,Pius Yanda,Noureddine Yassaa,and Taha Zatari.
Our heartfelt thanks go to the hosts and organizers of the scoping meeting and the four
Special Report on 1.5°C Lead Author Meetings. We gratefully acknowledge the support
from the host countries and institutions:World Meteorological Organization, Swi�erland;
Ministry of Foreign Affairs, and the National Institute for Space Research (INPE), Brazil;
Met Office and the University of Exeter,the United Kingdom; Swedish Meteorological and
Hydrological Institute (SMHI), Sweden; the Ministry of Environment Natural Resources
Conservation and Tourism, the National Climate Change Committee in the Department
of Meteorological Services and the Botswana Global Environmental Change Committee
at the University of Botswana, Botswana; and the government of the Republic of Korea.
The support provided by governments and institutions, as well as through contributions
to the IPCC Trust Fund, is thankfully acknowledged as it enabled the participation of the
author teams in the preparation of the Report.The efficient operation of the Working Group I
Technical Support Unit was made possible by the generous financial support provided by
the government of France and administrative and information technology support from the
Universite Paris Saday(France),Institut Pierre Simon Laplace QPSL)and the Laboratoire des
Sciences du Climat et de I'Environnement (LSCE). We thank the Norwegian Environment
Agency for supporting the preparation of the graphics for the Summary for Policymakers.
We thank the UNEP Library, who supported authors throughout the drafting process by
providing literature for the assessment.
4
Summary for Policymakers
We would also like to thankAbdalah Mokssit, Secretary of the IPCC,and the staff of the
IPCC Secretariat:Kerstin Stendahl,Jonathan Lynn,Sophie Schlingemann,Judith Ewa,Mxolisi
Shongwe,Jesbin Baidya,Werani Zabula,Nina Peeva,Joelle Fernandez,Annie Courtin,Laura
Biagioni and Oksana Ekzarho. Thanks are due to Elhousseine Gouaini who served as the
conference officer for the 48th Session of the IPCC.
Finally, our particular appreciation goes to the Working Group Technical Support Units
whose tireless dedication, professionalism and enthusiasm led the production of this
Special Report. This report could not have been prepared without the commitment of
members of the Working Group I Techniwl Support Unit, all new to the IPCC, who rose
to the unprecedented Sixth Assessment Report challenge and were pivotal in all aspects
of the preparation of the Report: Yang Chen, Sarah Connors, Melissa Gomis, Elisabeth
Lonnoy,Robin Matthews,Wilfran Moufouma-0kia,Clotilde Pean, Roz Pidcock,Anna Pirani,
Nicholas Reay,Tim Waterfield,and Xiao Zhou. Our warmest thanks go to the collegial and
collaborative support provided by Marlies Craig,Andrew Okem,Jan Pe�old,Melinda Tignor
and Nora Weyer from the WGII Technical Support Unit and Bhushan Kankal,Suvadip Neogi
and Joana Portugal Pereira from the WGIII Technical Support Unit.A special thanks goes
to Kenny Coventry, Harmen Gudde, Irene Lorenzoni, and Stuart Jenkins for their support
with the figures in the Summary for Policymakers, as well as Nigel Hawtin for graphical
support of the Report. In addition,the following contributions are gratefully acknowledged:
Jatinder Padda (copy edit), Melissa Dawes (copy edit), Marilyn Anderson (index),Vincent
Gregoire(layout)and Sarah le Rouzic (intern).
The Special Report website has been developed by Habitat 7, led by Jamie Herring, and
the report content has been prepared and managed for the website by Nicholas Reay and
Tim Waterfield.We gratefully acknowledge the UN Foundation for supporting the website
development.
5
Introduction
This Report responds to the invitation for IPCC'...to provide a Special Report in 2018 on the impacts of global warming of 1.5°C
above pre-industrial levels and related global greenhouse gas emission pathways'contained in the Decision of the 21 st Conference
of Parties of the United Nations Framework Convention on Climate Change to adopt the Paris Agreementl
The IPCC accepted the invitation in April 2016, deciding to prepare this Special Report on the impacts of global warming of
1.5°C above pre-industrial levels and related global greenhouse gas emission pathways,in the context of strengthening the global
response to the threat of dimate change,sustainable development,and efforts to eradicate poverty.
This Summary for Polirymakers (SPM) presents the key findings of the Special Report, based on the assessment of the available
scientific, techniwl and socio-economic literature' relevant to global warming of 1.5°C and for the comparison between global
warming of 1.5°C and 2°C above pre-industrial levels.The level of confidence associated with each key finding is reported using
the IPCC wlibrated language.' The underlying scientific basis of each key finding is indicated by references provided to chapter
elements. In the SPM,knowledge gaps are identified associated with the underlying chapters of the Report.
A. Understanding Global Warming of 1 .5°C`
A.1 Human activities are estimated to have caused approximately 1.0°C of global warmings above
pre-industrial levels, with a likely range of 0.8°C to 1.2°C. Global warming is likely to reach 1.5°C
between 2030 and 2052 if it continues to increase at the current rate. (high confidence) (Figure
SPM.1){1.2}
A.1.1 Reflecting the long-term warming trend since pre-industrial times,observed global mean surface temperature(GMST)for
the decade 200Cr2015 was 0.87°C Qikely between OJS°C and 0.99°C)s higher than the average over the 1850-1900
period (veryhigh confidence). Estimated anthropogenic global warming matches the level of observed warming to within
±z0% Qikely range). Estimated anthropogenic global warming is currently increasing at 0.2°C Qikely between 0.1°C and
0.3°C)per dewde due to past and ongoing emissions(high confidence).{1.2.1,Table 1.1,1.2A}
A.1.2 Warming greater than the global annual average is being experienced in many land regions and seasons,induding two to
three times higher in theArctic Warming is generally higher over land than over the ocean. (high confidence){1.2.1,1.2.2,
Figure 1.1,Figure 1.3,3.3.1,3.3.2}
A.1.3 Trends in intensiry and frequenry of some dimate and weather extremes have been detected over time spans during which
about 0.5°C of global warming occurred (medium confidence). This assessment is based on several lines of evidence,
including attribution studies for changes in extremes since 1950.{3.3.1,3.3.2,3.3.3}
1 Deusion 1/CP21,paagaph 21.
2 Theassessmentmversllteamreacceptedforpubll�tlonby15May2018.
3 EachHndinglsgroundedlnanevdluationofunderlNngevidenceandagreemen[AlevelofmnHdencelse.pressedusing(ivequallHers'.verylow,low,medlum,hlghandveryhlgh,and
rypeset In Ibllcs,for exemple,medium con/idence.The following terms have been used ro Indl�te tl�e assessed Ilkellhood of an outmme or a result.virWally certain 99-100%
pmbablllry,very Ilkely9�100%,Ilkely6Cr100%,aboutas Ilkelyas not33-66%,unllkely�33%,veryunllkely�10%,excepoonallyunllkely�1%.Addltional terms(e.tremelyllkely
9�100%,more Ilkely than nob5�100%,more unllkely tl�an Ilkely 0-<50%,e.tremely unllkely 0-5%)may also be used when appropnate.Assessed Ilkellhood Is rypeset In Ibllcs,
for e.ample,�erylikely.Thls Is mnsistentwitl�ARS.
4 SeealsoBoxSPM.1'.CoreConceptsCentralmtl�IsSpeualReport.
5 PresenNevel of globalwarming Is deHnedas the aveage ofa 30+,�ear penod centred on 2017 assuming the recentate ofwarming mntlnues.
6 Thls ange spans tl�e fouravdllable peer-reviewed estlmates of the observed GMST change and also acmwti foraddltlonal wcerbinrydue m possible shorPterm naWal vdnablllry.
[L21,Table 1.1]
6
Summary for Policymakers
A.2 Warming from anthropogenic emissions from the pre-industrial period to the present will persist for
centuries to millennia and will continue to cause further long-term changes in the climate system,
such as sea level rise, with associated impacts (high confidence), but these emissions alone are
unlikely to cause global warming of 1.5°C (medium confidence). (Figure SPM.1){1.2, 3.3, Figure 1.5}
A.2.1 Anthropogenic emissions (including greenhouse gases, aerosols and their precursors) up to the present are unlikely to
wuse further warming of more than 0.5°C over the next two to three decades(high confidence)or on a century time scale
(medium confidence).{1.2.4,Figure 1.5}
A.2.2 Reaching and sustaining net zero global anthropogenic CO3 emissions and dedining net non-0O3 radiative forcing would
halt anthropogenic global warming on multi-dewdal time scales (high confidence).The maximum temperature reached is
then determined by cumulative net global anthropogenic CO3 emissions up to the time of net zero CO3 emissions (high
confidence) and the level of nomCO, radiative forcing in the decades prior to the time that maximum temperatures are
reached (medium confidence). On longer time scales, sustained net negative global anthropogenic CO3 emissions and/
or further reductions in nomCO, radiative forcing may still be required to prevent further warming due to Earth system
feedbacks and to reverse ocean acidifiwtion (medium confidence) and will be required to minimize sea level rise (high
confidence).{Cross-Chapter Box 2 in Chapter 1,1.2.3,1.2.4,Figure 1.4,2.2.1,2.2.2,3.4.4.8,3.4.5.1,3.6.3.2}
A.3 Climate-related risks for natural and human systems are higher for global warming of 1.5°C than
at present, but lower than at 2°C (high confidence).These risks depend on the magnitude and rate
of warming,geographic location, levels of development and vulnerability, and on the choices and
implementation of adaptation and mitigation options (high confidence). (Figure SPM.2) {1.3, 3.3,
3.4, 5.6}
A.3.1 Impacts on natural and human systems from global warming have already been observed(high confidence).Many land and
ocean ecosystems and some of the services they provide have already changed due to global warming (high confidence).
(Figure SPM.2){1.4,3.4,3.5}
A.3.2 Future climate-related risks depend on the rate,peak and duration of warming. In the aggregate,they are larger if global
warming exceeds 1.5°C before returning to that level by 2100 than if global warming gradually stabilizes at 1.5°C,especially
if the peak temperature is high (e.g.,about 2°C) (high confidence).Some impacts may be long-lasting or irreversible,such
as the loss of some ecosystems(high confidence).{3.2,3.4.4,3.6.3,Cross-Chapter Box 8 in Chapter 3}
A.3.3 Adaptation and mitigation are already occurring (high confidence). Future dimate-related risks would be reduced by the
upscaling and acceleration of far-reaching, multilevel and cross-sectoral dimate mitigation and by both incremental and
transformational adaptation (high confidence).{1.2, 1.3,Table 3.5,4.2.2,Cross-Chapter Box 9 in Chapter 4, Box 4.2,Box
4.3,Box4.6,4.3.1,4.3.2,4.3.3,4.3.4,4.3.5,4.4.1,4.4.4,4.4.5,4.5.3}
7
Summary for Policymakers
Cumulative emissions of COz and future non-COz radiative forcing determine
the probability of limiting warming to 1.5°C
a)Observed global temperature change and modeled
responses to stylized anthropogenic emission and forcing pathways
G loba I wa rmi ng relative to 1850-1900(°C)
.�
is
Observed monthlyglobal
mean surface temperature
Estimated anthropogenic
ip warmingtodateand — ---
likelyrange � �
Likely range of modeled responses to stylized pathways
iet
ib,c&d)
a.s
mi� � ❑FasterCOzreductions(blueinb&c)resultinahigher
probability of limiting warmingto 1.5°C
❑No reduction of net non-COz radiative forcing(purple in d)
results in a lowerprobability of limitingwarmingto 1.5°C
° I i i i i i i
196� 198� 2��� 2�2� 2�4� 2�6� 2�8� Il��
b)Stylized net global COo emission pathways c)Cumulative net COo emissions d)Noo-COo radiative forcing pathways
BilliontonnesCozperyear(GtCoz/yr) BilliontonnesCoz(GtCoz) Wattspersquaremetre(W/m')
sp COzemissions a000 a
dedine from 2020
qp i to reach net zero in i � Non-Wz radiative forcing
or �40 or
2°°° ' � notreducedaker2030
3�
Cumulative COn
zp emissions in pathways
i000 reachingnetzeroin i i
io and i
i }
i
a a a
198� 2�2� 2�6� Il�� 198� 2�2� 2�6� Il�� 198� 2�2� 2�6� Il��
FasterimmediateWzemissionreductions MaximumtemperatureriseisdeterminedbycumulativenetWzemissionsandnetnon-COz
IimitcumulativeWzemissionsshownin radiativeforcingduetomethane,nitrousoxide,aerosolsandotheranthropogenicforcingagents.
panel(c).
Figure SPM.1 � Panel a�.Observed monthlyglobal mean surface temperature(GMST,grey Ilne up to 2017,fmm the HadCRUT4,GISTEMP,CotarrWay,and
NOAA datasets)change and estlmated anthmpogenlcglobal warming(solld orange Ilne up to 2017,with orange shading Indlcating assessed likely range).Orange
dashed armw and horizontal orange ermr bar show respectMely the central estlmate and likely range of the tlme at whlch 1.5°C Is reached if the arrent rate
of warming mntlnues.The grey plume on the right of panel a showsthe likely range of warming responses,mmputed with a simple dlmate model,to a sryllzed
pathway(hypothetical future)In whlch net COz emissions(qrey Ilne In panels b and c)dedlne In a stralght Ilne fmm 2020 to reach netzem'm 2055 and net non-
CQz radlative forcing(grey Ilne In panel d)'mcreases to 2030 and then dedlnes.The blue plume In panel a)shows the response to faster COz emissions reductlons
@lue Ilne In panel b),reaching netzem'm 204Q reducing amulatMe COz emissions(panel c).The purple plume showsthe response to net COz em Issions dedlning
to zem'm 2055,with net nonLOz forcing remalning cpnstant after 2030.Thevertical ermr bars on right of panel a)show the likely ranges(thln Ilnes)and central
terciles(33rd-66th percentlles,thlck Ilnes)of the estlmated dlstributlon ofwarming 'm 2100 underthesethree styllzed pathways.Uertical dotted error bars In
panels b,c and d show the likely range of hlstorical annual and amulative global net CQz emissions'm 2017(data from the Global Carbon Pmject)and of net
nonLOz radlative forcing'm 2011 from ARS,respectively.Vertical axes In panels c and d are scaled to represent appmxlmately equal effects on GMSL[L2.1,L23,
L2.4,2.3,Flgure L2 and Chapter 1 Supplementary Material,Cmss-ChapterBox 21n Chapter 1]
8
Summary for Policymakers
B. Projected Climate Change, Potential Impacts and Associated Risks
B.1 Climate models projed robust'differences in regional dimate charaderistics between present-day
and global warming of 1.5°C,s and between 1.5°C and 2°C a These differences indude increases
in: mean temperature in most land and ocean regions (high confidence), hot extremes in most
inhabited regions (high confidence), heavy precipitation in several regions (medium confidence),
and the probability of drought and precipitation deficits in some regions (medium confidence).
{3.3}
B.1.1 Evidence from attributed changes in some dimate and weather extremes for a global warming of about 0.5°C supports
the assessment that an additional 0.5°C of warming compared to present is associated with further detectable changes in
these extremes (medium confidence). Several regional changes in dimate are assessed to occur with global warming up
to 1.5°C compared to pre-industrial levels,induding warming of extreme temperatures in many regions(high confidence),
increases in frequenry,intensiry,and/or amount of heavy precipitation in several regions(high confidence),and an increase
in intensiTy or frequenry of droughts in some regions(medium confidence).{3.2,3.3.1,3.3.2,3.3.3,3.3.4,Table 3.2}
B.1.2 Temperature extremes on land are projected to warm more than GMST(high confidence):extreme hot days in mid-latitudes
warm by up to about 3°C at global warming of 1.5°C and about 4°C at 2°C,and extreme cold nights in high latitudes warm
by up to about 4.5°C at 1.5°C and about 6°C at 2°C (high confidence).The number of hot days is projected to increase in
most land regions,with highest increases in the tropics (high confidence).{3.3.1,3.3.2,Cross-Chapter Box 8 in Chapter 3}
B.1.3 Risks from droughts and precipitation deficits are projected to be higher at 2°C compared to 1.5°C of global warming in
some regions (medium confidence). Risks from heavy precipitation events are projected to be higher at 2°C compared to
1.5°C of global warming in several northem hemisphere high-latitude and/or high-elevation regions, eastern Asia and
eastern North America (medium confidence). Heavy precipitation associated with tropical rydones is projected to be
higher at 2°C compared to 1.5°C global warming (medium confidence). There is generally low confidence in projected
changes in heavy precipitation at 2°C compared to 1.5°C in other regions.Heavy precipitation when aggregated at global
scale is projected to be higher at 2°C than at 1.5°C of global warming (medium confidence).As a consequence of heavy
precipitation,the fraction of the global land area affected by flood hazards is projected to be larger at 2°C compared to
1.5°C of global warming (medium confidence).{3.3.1,3.3.3,3.3.4,3.3.5,3.3.6}
B.2 By 2100,global mean sea level rise is projected to be around 0.1 metre lower with global warming
of 1.5°C compared to 2°C (medium confidence). Sea level will continue to rise well beyond 2100
(high confidence), and the magnitude and rate of this rise depend on future emission pathways.
A slower rate of sea level rise enables greater opportunities for adaptation in the human and
ecological systems of small islands, low-lying coastal areas and deltas (medium confidence).
{3.3, 3.4, 3.6}
B.2.1 Model-based projections of global mean sea level rise(relative to 198Fr2005)suggest an indicative range of 0.26 to OJ7
m by 2100 for 1.5°C of global warming,0.1 m(0.04-0.16 m) less than for a global warming of 2°C (medium confidence).
A reduction of 0.1 m in global sea level rise implies that up to 10 million fewer people would be exposed to related risks,
based on population in the year 2010 and assuming no adaptation (medium confidence).{3.4.4,3.4.5,4.3.2}
B.2.2 Sea level rise will continue beyond 2100 even if global warming is limited to 1.5°C in the 21 st century(high confidence).
Marine ice sheet instabiliry in Antarctiw and/or irreversible loss of the Greenland ice sheet could result in multi-metre rise
in sea level over hundreds to thousands of years.These instabilities could be triggered at around 1.5°C to 2°C of global
warming (medium confidence). (Figure SPM.2){3.3.9,3.4.5,3.5.2,3.6.3,Box 3.3}
� ROIlO5I�I5IlEfE OSECI IO f11E3f1 IIl3I3I IE35INJ0�IIIfCIS OP CI�If113IE f110CIEI5 SIIOW�IIE 53f11E 51]fl OPC}I3f1]ES 3I IIIE]fICI p01fII5�IE,3fICI�Il3I CI�IHEfEfICES�Ifl I3f]E fE]IOf15 3fE SCdIISII�IIy
signiH�nt.
8 PmjectedchangeslnlmpactibetweendlfferenHevelsofglobalwdrmingaredeterminedwithrespectmchangesinglobalmeansur(acealrtempeaWre.
9
B.2.3 Increasing warming amplifies the exposure of small islands,low-lying coastal areas and deltas to the risks associated with
sea level rise for many human and ecological systems, induding increased saltwater intrusion,flooding and damage to
infrastructure(high confidence). Risks associated with sea level rise are higher at 2°C compared to 1.5°C.The slower rate
of sea level rise at global warming of 1.5°C reduces these risks, enabling greater opportunities for adaptation induding
managing and restoring natural coastal ecosystems and infrastructure reinforcement(medium confidence).(Figure SPM.2)
{3.4.5,Box 3.5}
B.3 On land, impacts on biodiversity and ecosystems, including species loss and extinction, are
projected to be lower at 1.5°C of global warming compared to 2°C. Limiting global warming to
1.5°C compared to 2°C is projected to lower the impacts on terrestrial, freshwater and coastal
ecosystems and to retain more of their services to humans (high confidence). (Figure SPM.2)
{3.4, 3.5, Box 3.4, Box 4.2, Cross-Chapter Box 8 in Chapter 3}
B.3.1 Of 105,000 species studied; 6% of insects,8% of plants and 4% of vertebrates are projected to lose over half of their
dimatiwlly determined geographic range for global warming of 1.5°C,compared with 18%of insects,16%of plants and
8% of vertebrates for global warming of 2°C (medium confidence). Impacts associated with other biodiversiry-related
risks such as forest fires and the spread of invasive species are lower at 1.5°C compared to 2°C of global warming (high
confidence).{3.4.3,3.5.2}
B.3.2 Approximately 4% (interquartile range 2-7%)of the global terrestrial land area is projected to undergo a transformation
of ecosystems from one rype to another at 1°C of global warming,compared with 13% (interquartile range 8-20%)at 2°C
(medium confidence).This indicates that the area at risk is projected to be approximately 50% lower at 1.5°C compared to
2°C(medium confidence).{3.43.1,3.4.3.5}
B.3.3 High-latitude tundra and boreal forests are particularly at risk of climate change-induced degradation and loss,with woody
shrubs already encroaching into the tundra (high confidence)and this will proceed with further warming. Limiting global
warming to 1.5°C rather than 2°C is projected to prevent the thawing over centuries of a permafrost area in the range of
1.5 to 2.5 million km' (medium confidence).{3.3.2,3.4.3,3.5.5}
B.4 Limiting global warming to 1.5°C compared to 2°C is projected to reduce increases in ocean
temperature as well as associated increases in ocean acidity and decreases in ocean oxygen levels
(high confidence). Consequently, limiting global warming to 1.5°C is projected to reduce risks
to marine biodiversity, fisheries, and ecosystems, and their functions and services to humans,
as illustrated by recent changes to Ardic sea ice and warm-water coral reef ecosystems (high
confidence).{3.3, 3.4, 3.5, Box 3.4, Box 3.5}
B.4.1 There is high confidence that the probabiliry of a sea ice-free Arctic Ocean during summer is substantially lower at global
warming of 1.5°C when compared to 2°C.With 1.5°C of global warming,one sea ice-free Arctic summer is projected per
century.This likelihood is increased to at least one per decade with 2°C global warming.Effects of a temperature overshoot
are reversible forArctic sea ice cover on decadal time scales(high confidence).{3.3.8,3.4.4J}
B.4.2 Global warming of 1.5°C is projected to shift the ranges of many marine species to higher latitudes as well as increase the
amount of damage to many ecosystems.It is also expected to drive the loss of coastal resources and reduce the productiviry of
fisheries and aquaculture(especially at low latitudes).The risks of dimate-induced impacts are projected to be higher at 2°C
than those at global warming of 1.5°C(high confidence).Coral reefs,for example,are projected to dedine by a further 70-90%
at 1.5°C(high confidence)with larger losses(>99%)at 2°C(very high confidence).The risk of irreversible loss of many marine
and coastal ecosystems increases with global warming,especially at 2°C or more(high confidence).{3.4.4,Box 3A}
9 Consistentwitl�eadlersWdles,Illustrative numberswere adopted 6om one recentmeb-sWdy.
10
Summary for Policymakers
B.4.3 The level of ocean acidification due to increasing CO3 concentrations associated with global warming of 1.5°C is projected to
ampliTy the adverse effects of warming,and even further at 2°C,impacting the growth,development,calcification,survival,
and thus abundance of a broad range of species,for example,from algae to fish(high confidence).{3.3.10,3.4A}
B.4.4 Impacts of dimate change in the ocean are increasing risks to fisheries and aquaculture via impacts on the physiology,
survivorship,habitat,reproduction,disease incidence,and risk of invasive species(medium confidence)but are projected to be
less at 1.5°C of global warming than at2°C.One global fishery model,forexample,projected a decrease in global annual catch
for marine fisheries of about 1.5 million tonnes for 1.5°C of global warming compared to a loss of more than 3 million tonnes
for 2°C of global warming(medium confidence).{3.4.4,Box 3A}
B.5 Climate-related risks to health, livelihoods, food security, water supply, human security, and
economic growth are projected to increase with global warming of 1.5°C and increase further with
2°C. (Figure SPM.2){3.4, 3.5, 5.2, Box 3.2, Box 3.3, Box 3.5, Box 3.6, Cross-Chapter Box 6 in Chapter
3, Cross-Chapter Box 9 in Chapter 4, Cross-Chapter Box 12 in Chapter 5, 5.2}
B.5.1 Populations at disproportionately higher risk of adverse consequences with global warming of 1.5°C and beyond indude
disadvantaged and vulnerable populations,some indigenous peoples,and local communities dependent on agricultural or
coastal livelihoods (high confidence). Regions at disproportionately higher risk indudeArctic ecosystems,dryland regions,
small island developing states,and Least Developed Countries (high confidence). Poverry and disadvantage are expected
to increase in some populations as global warming increases;limiting global warming to 1.5°C,compared with 2°C,could
reduce the number of people both exposed to dimate-related risks and susceptible to poverry by up to several hundred
million by 2050 (medium confidence).{3.4.10,3.4.11,Box 3.5,Cross-Chapter Box 6 in Chapter 3,Cross-Chapter Box 9 in
Chapter 4,Cross-Chapter Box 12 in Chapter 5,4.2.2.2,5.2.1,5.2.2,5.2.3,5.6.3}
B.5.2 Anyincreaseinglobalwarmingisprojectedtoaffecthumanhealth,withprimarilynegativeconsequences(highconfidence).
Lower risks are projected at 1.5°C than at 2°C for heat-related morbidiry and mortaliry (very high confidence) and for
ozone-related mortaliry if emissions needed for ozone formation remain high (high confidence). Urban heat islands often
ampliTy the impacts of heatwaves in cities (high confidence). Risks from some vector-borne diseases,such as malaria and
dengue fever,are projected to increase with warming from 1.5°C to 2°C,induding potential shifts in their geographic range
(high confidence).{3.4J,3.4.8,3.5.5.8}
B.5.3 Limiting warming to 1.5°C compared with 2°C is projected to result in smaller net reductions in yields of maize,rice,wheat,
and potentially other cereal crops, particularly in sub-Saharan Africa,SoutheastAsia,and Central and South America,and
in the CO3 dependent nutritional qualiry of rice and wheat(high confidence). Reductions in projected food availabiliry are
larger at 2°C than at 1.5°C of global warming in the Sahel, southern Afriw,the Mediterranean,central Europe,and the
Amazon(medium confidence).Livestock are projected to be adversely affected with rising temperatures,depending on the
extent of changes in feed qualiry,spread of diseases,and water resource availabiliry(high confidence).{3.4.6,3.5.4,3.5.5,
Box 3.1,Cross-Chapter Box 6 in Chapter 3,Cross-Chapter Box 9 in Chapter 4}
B.5.4 Depending on future socio-economic conditions, limiting global warming to 1.5°C compared to 2°C may reduce the
proportion of the world population exposed to a climate change-induced increase in water stress by up to 50%,although
there is considerable variabiliry between regions (medium confidence). Many small island developing states could
experience lower water stress as a result of projected changes in aridiry when global warming is limited to 1.5°C, as
compared to 2°C(medium confidence).{3.3.5,3.4.2,3.4.8,3.5.5,Box 3.2,Box 3.5,Cross-Chapter Box 9 in Chapter 4}
B.5.5 Risks to global aggregated economic growth due to dimate change impacts are projected to be lower at 1.5°C than at
2°C by the end of this century10 (medium confidence).This exdudes the costs of mitigation,adaptation investments and
the benefits of adaptation. Countries in the tropics and Southern Hemisphere subtropics are projected to experience the
largest impacts on economic growth due to dimate change should global warming increase from 1.5°C to 2°C (medium
confidence).{3.5.2,3.53}
10 Here,Impacts on emnomlc gmwtl�refer ro changes In gmss domestic product(GDP).Many Impacti,such as loss of human Ilves,ml Wal henbge and ems;rstem services,are dlfHcult
ro vdlue and monetlze.
11
B.5.6 Exposure to multiple and compound dimate-related risks increases between 1.5°C and 2°C of global warming,with greater
proportions of people both so exposed and susceptible to poverry in Afriw and Asia (high confidence). For global warming
from 1.5°C to 2°C,risks across energy,food,and water sectors could overlap spatially and temporally,creating new and
exacerbating current hazards, exposures, and vulnerabilities that could affect increasing numbers of people and regions
(medium confidence).{Box 3.5,3.3.1,3.4.5.3,3.4.5.6,3.4.11,3.5.4.9}
B.SJ There are multiple lines of evidence that since ARS the assessed levels of risk increased for four of the five Reasons for
Concem (RFCs) for global warming to 2°C (high confidence).The risk transitions by degrees of global warming are now:
from high to very high risk between 1.5°C and 2°C for RFC1 (Unique and threatened systems) (high confidence); from
moderate to high risk between 1°C and 1.5°C for RFC2 (Extreme weather events)(medium confidence);from moderate to
high risk between 1.5°C and 2°C for RFC3 (Distribution of impacts)(high confidence);from moderate to high risk between
1.5°C and 2.5°C for RFC4(Global aggregate impacts) (medium confidence);and from moderate to high risk between 1°C
and 2.5°C for RFCS (Large-swle singular events)(medium confidence).(Figure SPM.2){3.4.13; 3.5,3.5.2}
B.6 Most adaptation needs will be lower for global warming of 1.5°C compared to 2°C(high confidence).
There are a wide range of adaptation options that can reduce the risks of climate change (high
confidence). There are limits to adaptation and adaptive capacity for some human and natural
systems at global warming of 1.5°C,with associated losses(medium confidence).The number and
availability of adaptation options vary by sector (medium confidence). {Table 3.5, 4.3, 4.5, Cross-
Chapter Box 9 in Chapter 4, Cross-Chapter Box 12 in Chapter 5}
B.6.1 A wide range of adaptation options are available to reduce the risks to natural and managed ecosystems(e.g.,ecosystem-
based adaptation, ecosystem restoration and avoided degradation and deforestation, biodiversity management,
sustainable aquaculture,and local knowledge and indigenous knowledge),the risks of sea level rise(e.g.,coastal defence
and hardening), and the risks to health, livelihoods, food, water, and economic growth, especially in rural landscapes
(e.g., efficient irrigation, social safety nets, disaster risk management, risk spreading and sharing, and community-
based adaptation) and urban areas (e.g.,green infrastructure,sustainable land use and planning,and sustainable water
management) (medium confidence).{4.3.1,4.3.2,4.3.3,4.3.5,4.5.3,4.5.4,5.3.2,Box 4.2,Box 4.3,Box 4.6,Cross-Chapter
Box 9 in Chapter 4}.
B.6.2 Adaptation is expected to be more challenging for ecosystems,food and health systems at 2°C of global warming than for
1.5°C(medium confidence).Some vulnerable regions,induding small islands and Least Developed Countries,are projected
to experience high multiple interrelated dimate risks even at global warming of 1.5°C (high confidence). {3.3.1, 3.4.5,
Box 3.5,Table 3.5,Cross-Chapter Box 9 in Chapter 4,5.6,Cross-Chapter Box 12 in Chapter 5,Box 5.3}
B.6.3 Limits to adaptive capaciry exist at 1.5°C of global warming, become more pronounced at higher levels of warming and
vary by sector,with site-specific implications for vulnerable regions,ecosystems and human health (medium confidence).
{Cross-Chapter Box 12 in Chapter 5,Box 3.5,Table 3.5}
12
Summary for Policymakers
How the level of global warming affects impacts and/or risks associated with
the Reasons for Concern (RFCs) and selected natural, managed and human
syste ms
Five Reasons For Concern (RFCs) illustrate the impacts and risks of
different levels of global warming for people,economies and ecosystems
across sectors and re IOf1S. Purple indicatesvery high
g risks of severe impacts/risks
and the presence of
significant irreversibility or
Impacts and risks associated with the Reasons for Concern(RFCs) the persistence of
v ____ ____ ____ ____ ____
climate-related hazards,
� � combinedwithlimited
t verynign abilitytoadaptduetothe
�_zo � M nature of the hazard or
v' I� �I� � M Hign impacts/risks.
a- is
a- ,IH �IM jIM Redindicatessevereand
,�a i.o widespread impacts/risks.
= �IM moaera<e yellowindicatesthat
"a IN IM-� impacts/risksaredetectable
�� IN
- unae<ec�abie andattributabletoclimate
�v o changewithatleastmedium
RFCl RFQ RFC3 RFC4 RFCS �evelMadditional confidence.
Uniqueand EMreme Distribution Global Largescale impa¢/rispaue Whiteindicatesthatno
threatened weather ofim acts a re ate sin ular <ouima<ecnange
P 66 6 6 impactsaredetectableand
systems events impacts events attributabletoclimate
change.
Impacts and risks for selected natural,managed and human systems
m ---- --
fi_ I� �, ; m
�=2.0 � i M i M
v> IH fIH �IM
�- 1.5 iIM
�� i
„.a 1.0 IVH �IM M � H
�n ' ry� 'I,� ' H
ma IIHH IH H IH IM �
�i p
Warm-water Mangroves Small-scale Arctic Terrestrial Coastal Flwial Crop Tourism Heat-related
mrals low-latitude region emrystems flooding flooding yields morbidity
fsheries and mortality
Confdenre level fortnnsitiore L=Low,M=Medium,H=High and VH=Very high
Figure SPM.2� FMe'mtegratMe reasons for cpncem(RFCs)pmvide a framework for summarizing key Impacts and risks across sectors and reglons,and were
'mtmduced'm the IPCC ThlydAssessment Report. RFCs Illustrate the Impllcatlons of globalwarming for peoplg ecpnomles and ecprystems. Impacts and/or risks
for each RFC are based on assessment of the new Ilterature that has appeared.As InARS,thls Ilteraturewas used to make espertjudgmentsto assess the levels
of global warming at whlch levels of Im pact and/or risk are undetectable,moderate,hlgh orvery hlgh.The selectlon of Im pacts and risks to natural,managed and
human rystems'm the lower panel Is IllustratMe and Is not'mtended to be fully cpmprehensive.[3.4,3.5,3.5.2.1,3.5.2.2,3.5.23,3.5.2.4,3.5.2.5,5.4.1,5.53,
5.6.1,Box 3.4]
RFC7 Unique and threatened systems:ecploglcal and human rystemsthat have restricted geographlc ranges cpnstralned bydlmate-related cpndltlonsand
have hlgh endem Ism or other dlst'mctMe pmpertles.Exam ples'mdude cpral reefs,theArctic and Its Indlgenous people,mountain glaciers and blodlversiTy hotspots.
RFC2 6Rreme weather eventr.risks/Impacts to human health,IMellhoods,assets and ecprystems from extremeweatherevents such as heatwaves,heavy raln,
dmught and associated wildfi res,and cpastal flooding.
RFC3 Distribution of impactr. risks/Impacts that dlspmportlonately affect partlalargmups due to uneven dlstributlon of physical dlmate change hazards,
eeposure orvulnerablllry.
RFC4 Global aggregate impacts:global monetary damage,globabscale degradatlon and loss of ecprystems and blodMersiTy.
RFCS large-scale singular events:are relatively large,abrupt and sometlmes Irreversible changes In rystemsthat are caused byglobal warming Examples
'mdude dlsintegratlon of the Greenland and Antarctic Ice sheets.
13
C. Emission Pathways and System Transitions Consistent with 1 .5°C
Global Warming
C.1 In model pathways with no or limited overshoot of 1.5°C, global net anthropogenic CO,emissions
decline by about 45% from 2010 levels by 2030 (40-60% interquartile range), reaching net zero
around 2050 (2045-2055 interquartile range). For limiting global warming to below 2°C" CO,
emissions are projected to decline by about 25% by 2030 in most pathways(1�30% interquartile
range) and reach net zero around 2070 (206�2080 interquartile range). Non-CO, emissions in
pathways that limit global warming to 1.5°C show deep reductions that are similar to those in
pathways limiting warming to 2°C. (high confidence)(Figure SPM.3a){2.1, 2.3,Table 2.4}
C.1.1 CO3 emissions reductions that limit global warming to 1.5°C with no or limited overshoot can involve different portfolios of
mitigation measures,striking different balances between lowering energy and resource intensiry,rate of decarbonization,
and the reliance on carbon dioxide removal. Different portfolios face different implementation challenges and potential
synergies and trade-offs with sustainable development. (high confidence)(Figure SPM.3b){2.3.2,2.3.4,2.4,2.5.3}
C.1.2 Modelled pathways that limit global warming to 1.5°C with no or limited overshoot involve deep reductions in emissions
of inethane and black carbon (35% or more of both by 2050 relative to 2010).These pathways also reduce most of the
cooling aerosols,which partially offsets mitigation effects for two to three decades. NomCO, emissions" can be reduced
as a result of broad mitigation measures in the energy sectoc In addition, targeted nomCO, mitigation measures can
reduce nitrous oxide and methane from agriculture, methane from the waste sector, some sources of black wrbon, and
hydrofluorocarbons. High bioenergy demand can increase emissions of nitrous oxide in some 1.5°C pathways,highlighting
the importance of appropriate management approaches. Improved air qualiry resulting from projected reductions in many
non-0O3 emissions provide direct and immediate population health benefits in all 1.5°C model pathways.(high confidence)
(Figure SPM.3a){2.2.1,2.3.3,2.4.4,2.5.3,4.3.6,5.4.2}
C.1.3 Limiting global warming requires limiting the total cumulative global anthropogenic emissions of CO3 since the pre-
industrial period,that is,staying within a total wrbon budget(high confidence)." By the end of 2017,anthropogenic CO3
emissions since the pre-industrial period are estimated to have reduced the total wrbon budget for 1.5°C by approximately
2200 ± 320 GtCO, (medium confidence). The associated remaining budget is being depleted by current emissions of
qz ±3 GtCO, per year(high confidence).The choice of the measure of global temperature affects the estimated remaining
wrbon budget.Using global mean surface air temperature,as in ARS,gives an estimate of the remaining wrbon budget of
580 GtCO,for a 50%probabiliry of limiting warming to 1.5°C,and 420 GtCO,for a 66%probabiliry(medium confidence)."
Alternatively,using GMST gives estimates of 770 and 570 GtCO„for 50%and 66% probabilities,'s respectively (medium
confidence). Uncertainties in the size of these estimated remaining carbon budgets are substantial and depend on several
factors.Uncertainties in the dimate response to CO3 and nomCO,emissions contribute±q00 GtCO,and the level of historic
warming contributes±z50 GtCO,(medium confidence).Potential additional wrbon release from future permafrost thawing
and methane release from wetlands would reduce budgets by up to 100 GtCO, over the course of this century and more
thereafter(medium confidence). In addition,the level of non-0O3 mitigation in the future could alter the remaining carbon
budget by 250 GtCO, in either direction (medium confidence). {1.2.4, 2.2.2, 2.6.1,Table 2.2, Chapter 2 Supplementary
Material}
C.1 A Solar radiation modification (SRM) measures are not induded in any of the available assessed pathways.Although some
SRM measures may be theoretically effective in reducing an overshoot,they face large uncertainties and knowledge gaps
11 References ro patl�v✓d;rs Ilmitlng globalwarming ro 2°C are based on a 66%probablllryofstaying below 2°C.
12 NonLOi emissions Induded In tl�ls Reportare all anthmpogenicemissions otl�er tl�an COithat result In adlative forung.These Indude shorPllved dlmate forcers,such as metl�ane,
SOf11E HOOfIf13IECI]35E5,OZOfIE pfECll606,3EfO50I5 Of 3EfO50I pfECll606,SOC}I35IlI3CI:�I{JOf13fICI SOIpIIOf CI�IOXICIE,fESpECIIVEIy,35 W EII 35IOf1]��NECI]fEEfIIl005E]35E5,SOC}I35 fII V005
O;JCIE Of SOf11E HOOfIf13IECI]35E5.TIIE 2CI�13IIVE POfUfI]3550U3IECI W 1�I1 fIOfILOt Ef1115510f15 3fICI C}I3f1]ES�Ifl 501{3CE 3IIlECIO�IS fEPEffECI IO 35 fl0fl-COL 2CI�13IIVE POfUfI].[L.Z.I]
13 There Is a dear suentiHcbasis fora robl carbon budget mnsistentwitl�Ilmitlng global wdrming m 1.5°C.However,neither tl�ls mbl�rbon budget northe fiaction of thls budget
bken up by past emissions were assessed In tl�ls Report.
14 Irrespective of tl�e meamre of global tempea Wre used,updated understanding and further advdnces In methods have led ro an'mUease In tl�e estimated remaining�rbon budget of
about 300 GtCOi mmpared mARS.(medium con/idence)[222]
15 These estlmates use observed GMA m 2006-2015 and estlmate fuWre tempeamre changes using near mnc�e alr tempea Wres.
14
Summary for Policymakers
as well as substantial risks and institutional and social constraints to deployment related to governance,ethics,and impacts
on sustainable development. They also do not mitigate ocean acidification. (medium confidence) {4.3.$ Cross-Chapter
Box10in Chapter4}
Global emissions pathway characteristics
General characteristics of the evolution of anthropogenic net emissions of COz,and total emissions of
methane,black carbon,and nitrous oxide in model pathways that limit global warmingto 1.5°C with no or
limited overshoot. Net emissions are defined as anthropogenic emissions reduced by anthropogenic
removals.Reductions in net emissions can be achieved through different portfolios of mitigation measures
illustrated in FigureSPM.3b.
Non-0O2 emissions relative to 2010
Global total net COz emissions Emissions of non-COz forcers are also reduced
or limited in pathways limiting global warming
Billion tonnes of COz/yr to 1.5°C with no o r limited overshoot,but
so they do not reach zero globally.
Methane emissions
40 Inpa[hwayslimi[ingglobalwarming[o1.5�C i
wi[h no or limited overshoot as well asin
pa[hways wi[h a higher overshoot,CO2 emissions
so are reduced[o ne[zero globally around 2050. —
0
2020 2040 2060 2080 2100
20
Black carbon emissions
1
10
Fou r i Ilustrative model pathways�
o. o
�� ��pi 2020 2040 2060 2080 2100
P3
Nitrous oxide emissions
io .
P3
1 —
20 _
— P4
0 .
2010 2020 2Q40 2040 2050 2060 20�0 2080 2090 2100 2020 2040 2060 2080 2100
Tim ing Of net Zero COz Pathv✓ays llm IHng glo ba lv✓a rming m 15°Cwlth no or limited overshmt
Linewidthsdepictthe5-95th f pa��yswlmhigheroversh000
pefCentile and the 25-75th pamways umltlng globalwarming below2°C
percenti le of scenarios (No�shown a bove)
Figure5PM.3a� Globalemissionspathwaycharacteristics.ThemalnpanelshowsglobalnetanthropogenlcCQzemissionslnpathwaysllmltingglobalwarming
to 1.5°C with no or Ilm Ited(less than 0.1°C)overshoot and pathwayswith hlgher overshoot.The shaded area shows the full range for pathways analysed'm thls
Report.The panels on the right show non-CQz emissions ranges forthree cpmpoundswith large hlstorical forcing and a substantlal portlon of emissions cpming
fmm sources dlst'mct fmm those central to CQz mltlgatlon.Shaded areas'm these panels showthe 5-95°/(Ilght shading)and'mterquartlle(dark shading)ranges
of pathways Ilmlting global warming to 1.5°C with no or Ilmlted overshoot.Box and whlskers at the bottom of the figure showthe tlming of pathways reaching
globalnetzemCQzemissionlevels,andacpmparisonwithpathwaysllmltingglobalwarmingto2°Cwithatleast66°/pmbablllTy.Pourlllustrativemodelpathways
are hlghllghted'm the maln panel and are labelled P1,P2,P3 and P4,mrresponding to the LED,S1,S2,and SS pathways assessed In Chapter 2.Descriptlons and
characteristicsofthese pathwaysare avallable'm FlgureSPM3b.[2.1,2.2,23,Flgure 2.5,Flgure 2.1Q Flgure 2.11]
15
Characteristics of four illustrative model pathways
Different mitigation strategies can achieve the net emissions reductions that would be required to follow a
pathway that limits global warming to 1.5°C with no or limited overshoot.All pathways use Carbon Dioxide
Removal (CDR),butthe amountvaries across pathways,as do the relative contributions of Bioenergy with
Carbon Capture and Storage (BECCS) and removals in the Agriculture, Forestry and Other Land Use(AFOLU)
sector.This has implications for emissions and several other pathway characteristics.
Breakdown of contributions to global net COz emissions in four illustrative model pathways
Fossilfuelandindustry AFOLU BECCS
BillionMnnesCOzperyear(GK6./yr) BillionMnnesCOzperyear(GKOx/yr) BilliontonnesCOzperyear(GKYh/yr) BillionMnnesCOzperyear(GK6./yr)
P1 P2 P3 P4
0
uoo
iPl: Ascenarioinwhichsocial, i P2: Ascenariowithabroadfomson i P3: Amiddle-of4he-roadscenarioin i P4:Aresource-andenergy-intensive i
businessandtechnologicalinnovations wslainabiliTyincludingenergy whichsociMalaswellastechnological scenarioinwhichemnomicgrov✓thand
resultinlowerenergydemandupto � intensity,humandevelopment, � developmentfollowshistorical � globalizationleadtowidespread
I 2osowhilelivingstandardsrise, I emnomicmnvergenceand I pattems.Emissionsreductionsare I adoptionofgreenhouse-gas-intensive I
especialtyintheglobal5outh.A ' internationalmoperatioqaswellas ' maintyachievedbychangingthewayin ' lifes[yles,includinghighdemandfor '
Idownsizedenergyrystemenables I shittrtowardswstainableandhealthy I whichenergyandproductsare I fransportationfuelsandlives[ock I
apiddecarbonizationofenergysuppty. mnsumptionpattems,low-carbon produced,andmalesserdegreeby products.Emissionsreductionsare
iAfforeslationistheontyCDRoption I technologyinnovatioqand i reductionsindemand i maintyachievedthroughtechnological i
mnsidered;neitherfossilfuelswithC6 wellmanagedlandrystemswith means,maKngstronguseofCDR
ino�BECCSareused i IimitedsociMalacceplabiliTyfo�BECCS. i i throughthedeploymentofBECCS. i
_....._...__..'.�. �....._.....—'..__....__... �...� ! �'__..._�
..—'...._' --�'. � .__--•
..__....__..._. `
Globalintlicamrs 1 pl � py , pg � pq i Interquartilerenge
Pothwoyclossiflmtion I Noorlimitedovershoot •Noorlimitedovershoot i Noorlimitedovershoot I Higherovershoot .Noorlimitedovershoot
mzemissloncnongelnzoso(/retromio) � -sa � a� : ai a � (-sa,ao�
lnmso(/retromio) � -ss � �s � -si � -s� ' (-io�,�a�
Kyoro�rreemisslo�lnzoso(/retromio) � -so � as as � -z � (-si,-ss�
lnmso(/retromio) � -az � as � -�a : -ao ' (�a,-ai�
qnolenergydemond"lnzo3o(%relromlo) : -ls : -5 ' v � 35 � (-1��)
lnmso(/retromio) � az � z � u ' aa � (-n,zz�
kenewobleshorelnelechlcltylnzo3o(%) ' So ' sfl � 4fl � u • (4�,55)
lnmso(/) � n � ai � � ' �o � (es,ae�
Prlmoryenergybomcoo!lnzo3o(%relrozolo) � -�fl � �1 � -�5 � -55 ' (-�fl,-55)
!n mso(/ret ro mio) . -s� . -n ' -ra � -s� � (�s,-�a�
rromolunzoso(/retromio) � -s� � -� � a � ae � (-sa��
lnmso(/retromio) � -a� � -so � -ai � az . (-�a,ai�
rromgaslnzoso(/retromio) � -u � -m ; � ' a� � (-ze,u�
lnmso(/retromio) � -�a � -sa � u � aa � (-se,e�
rromn�cteorinzoso(/retromio) � ss � as � sa � ioe � (aa,ioz�
lnmso(/retromio) � �so � sa � soi : aea ' (si,iso�
rromblomosslnzoso(/retromio) : -n : o ' ae � -i � (zs,ao�
lnmso(/retromio) � -ie � as � iu � aia � (izs,zei�
bomnon�lomossrenewobtulnzo3o(/retrozolo)i a3o ' 4�0 � 31s � 110 : (z4s,435)
lnmso(/retromio) � a� � �n : a�a ' i�� � (s�e,izss�
c�m�mrl�eccs�nrltuoo(e�co) � o � aaa � ea� � iva ' (ssqiov�
orwnlcneEas(erco,) . o . isi ' aia � nsi � (aeqeez�
Londoreoorbloenergycropslnzoso(mlttlonkrN) � az � 0.5 � za : zz � (15}.z)
AgAculNvolCH�emkslor�sln2030(%velN2010) � -24 � -08 � 1 � 14 � (-30,-n�
lnmso(/retromio) � -� � �s . -zs ' z � (a�,-za�
agAc�tmrot�oemisslo�slnzoso(/retromio) s -ze � �s � a � (-u��
lnmso(/retromio) � e � -ze o � as � (-ze,i�
NoiE:lndlcomahovebeenselectedmshowglobolhendsldenNt]edbytheChopter2azsersment 'KyomgasemisslorisorebosedonlPCCSecondAseamentReportGWPloo
NOHonolondsecmrolcho�octerlsHrscondlHersubstunHo!lybomtheglobolhendsshownoboe. "Chongulnenergydemondoreossoclotedwlthlmprovementrinenergy
efflclencyond behoNourchonge
16
Summary for Policymakers
Figure5PM3b� CharacteristicsoffourlllustratMemodelpathways'mrelatlontoglobalwarmingof1.5°C 'mtmduced'mFlgureSPM3a.Thesepathwayswere
selected to show a range of potentlal mltlgatlon approaches and varywidely'm thelr projected energy and land use,aswell as thelr assumptlons about future
socio-ecpnomlc developments,'mduding ecpnomlcand populatlon gmwth,equlTyand sustalnablllTy.A breakdown of the global net anthmpogenlcCQz emissions
'mto the cpntributlons'm terms of CQz emissionsfmm fossil fuel and Industry;agrialture,forestryand other land use(AFOW);and bloenergywith carbon capture
and storage(BECCS)Is shownAFOW estlmates reported here are not necessarilymmparablewith cpuntrieS estlmates. Furthercharacteristicsforeach of these
pathways are Ilsted below each pathway.These pathways Illustrate relatMe global dlfferences In mltlgatlon strategles, but do not represent central estlmates,
natlonal strategles,and do not Indlcate requlrements. Pormmparison,the right-most cplumn showsthe'mterquartlle ranges across pathwayswith no or Ilmlted
overshoot of 1.5°C. Pathways P1, P2,P3 and P4 mrrespond to the LED,S1,S2 and SS pathways assessed In Chapter 2(Flgure SPM3a). [2.2.1, 2.3.1, 23.2,
233,23.4,2.4.1,2.4.2,2.4.4,2.53,Figure 2.5,Figure 2.6,Figure 2.9,Figure 2.1Q Figure 2.11,Figure 2.14,Figure 2.15,Figure 2.16,Figure 2.V,Figure 2.24,
Flgure 2.25,Table 2.4,Table 2.6,Table 2J,Table 2.9,Table 4.1]
C.2 Pathways limiting global warming to 1.5°C with no or limited overshoot would require rapid
and far-reaching transitions in energy, land, urban and infrastructure (including transport and
buildings), and industrial systems(high confidence). These systems transitions are unprecedented
in terms of scale, but not necessarily in terms of speed, and imply deep emissions reductions in all
sectors, a wide portfolio of mitigation options and a significant upscaling of investments in those
options(medium confidence).{2.3,2.4, 2.5,4.2,4.3,4.4,4.5}
C.2.1 Pathways that limit global warming to 1.5°C with no or limited overshoot show system changes that are more rapid and
pronounced over the next two decades than in 2°C pathways (high confidence).The rates of system changes associated
with limiting global warming to 1.5°C with no or limited overshoot have occurred in the past within specific sectors,
technologies and spatial contexts, but there is no documented historic precedent for their scale (medium confidence).
{2.3.3,2.3.4,2.4,2.5,4.2.1,4.2.2,Cross-Chapter Box 11 in Chapter 4}
C.2.2 In energy systems, modelled global pathways (considered in the literature) limiting global warming to 1.5°C with no or
limited overshoot (for more details see Figure SPM.3b) generally meet energy service demand with lower energy use,
induding through enhanced energy efficienry, and show faster electrification of energy end use compared to 2°C (high
confidence). In 1.5°C pathways with no or limited overshoot,low-emission energy sources are projected to have a higher
share, compared with 2°C pathways, particularly before 2050 (high confidence). In 1.5°C pathways with no or limited
overshoot, renewables are projected to supply 70-85% (interquartile range) of electriciry in 2050 (high confidence). In
electriciry generation, shares of nudear and fossil fuels with wrbon dioxide capture and storage (CCS) are modelled to
increase in most 1.5°C pathways with no or limited overshoot. In modelled 1.5°C pathways with limited or no overshoot,
the use of CCS would allow the electriciry generation share of gas to be approximately 8% (3-11% interquartile range)
of global electriciry in 2050,while the use of coal shows a steep reduction in all pathways and would be reduced to dose
to 0% (0-2% interquartile range) of electriciry (high confidence).While acknowledging the challenges, and differences
between the options and national circumstances,political,economic,social and techniwl feasibiliry of solar energy,wind
energy and electriciry storage technologies have substantially improved over the past few years (high confidence).These
improvements signal a potential system transition in electriciTy generation. (Figure SPM.3b){2.4.1,2.4.2, Figure 2.1,Table
2.6,Table 2J,Cross-Chapter Box 6 in Chapter 3,4.2.1,4.3.1,4.3.3,4.5.2}
C.2.3 CO3 emissions from industry in pathways limiting global warming to 1.5°C with no or limited overshoot are projected to
be about 65-90% (interquartile range) lower in 2050 relative to 2010, as compared to 50-80% for global warming of
2°C (medium confidence). Such reductions can be achieved through combinations of new and existing technologies and
practices, including electrification, hydrogen,sustainable bio-based feedstocks, product substitution,and carbon capture,
utilization and storage (CCUS). These options are technically proven at various scales but their large-scale deployment
may be limited by economic, financial, human capaciry and institutional constraints in specific contexts, and specific
characteristics of large-scale industrial installations. In industry, emissions reductions by energy and process efficiency
by themselves are insufficient for limiting warming to 1.5°C with no or limited overshoot(high confidence). {2.4.3,4.2.1,
Table 4.1,Table 4.3,4.3.3,4.3.4,4.5.2}
C.2.4 Theurbanandinfrastructuresystemtransitionconsistentwithlimitingglobalwarmingto1.5°Cwithnoorlimitedovershoot
would imply,forexample,changes in land and urban planning practices,aswell as deeperemissions reductions in transport
and buildings compared to pathways that limit global warming below 2°C (medium confidence). Technical measures
17
and practices enabling deep emissions reductions include various energy efficiency options. In pathways limiting global
warming to 1.5°C with no or limited overshoot,the electricity share of energy demand in buildings would be about 55-75%
in 2050 compared to 5�70% in 2050 for 2°C global warming (medium confidence). In the transport sector,the share of
low-emission final energy would rise from less than 5% in 2020 to about 35-65% in 2050 compared to 25-45% for 2°C
of global warming (medium confidence). Economic, institutional and socio-cultural barriers may inhibit these urban and
infrastructure system transitions,depending on national,regional and local circumstances,capabilities and the availabiliry
of capital (high confidence).{2.3.4,2.4.3,4.2.1,Table 4.1,4.3.3,4.5.2}
C.2.5 Transitions in global and regional land use are found in all pathways limiting global warming to 1.5°C with no or limited
overshoot,but their scale depends on the pursued mitigation portfolio.Model pathways that limit global warming to 1.5°C
with no or limited overshoot project a 4 million km'reduction to a 2.5 million km'increase of non-pasture agricultural land
for food and feed crops and a 0.5-11 million km'reduction of pasture land,to be converted into a 0-6 million km'increase
of agricultural land for energy crops and a 2 million km' reduction to 9.5 million km' increase in forests by 2050 relative
to 2010 (medium confidence)Js Land-use transitions of similar magnitude wn be observed in modelled 2°C pathways
(medium confidence).Such large transitions pose profound challenges for sustainable management of the various demands
on land for human settlements, food, livestock feed, fibre, bioenergy, carbon storage, biodiversity and other ecosystem
services(high confidence). Mitigation options limiting the demand for land indude sustainable intensification of land-use
practices,ecosystem restoration and changes towards less resource-intensive diets(high confidence).The implementation
of land-based mitigation options would require overcoming socio-economic, institutional, technological, financing and
environmental barriers that differ across regions (high confidence). {2.4.4, Figure 2.24, 4.3.2, 4.3J, 4.5.2, Cross-Chapter
Box 7 in Chapter 3}
C.2.6 Additional annual average energy-related investments for the period 2016 to 2050 in pathways limiting warming to
1.5°C compared to pathways without new dimate policies beyond those in place today are estimated to be around 830
billion USD2010(range of 150 billion to 1700 billion USD2010 across six models").This compares to total annual average
energy supply investments in 1.5°C pathways of 1460 to 3510 billion USD2010 and total annual average energy demand
investments of 640 to 910 billion USD2010 for the period 2016 to 2050. Total energy-related investments increase by
about 12% (range of 3%to 24%) in 1.5°C pathways relative to 2°C pathways.Annual investments in low-carbon energy
technologies and energy efficienry are upscaled by roughly a factor of six(range of factor of 4 to 10) by 2050 compared to
2015 (medium confidence).{2.5.2,Box 4.8,Figure 2.27}
C.2J Modelled pathways limiting global warming to 1.5°C with no or limited overshoot project a wide range of global average
discounted marginal abatement costs over the 21st century.They are roughly 3-4 times higher than in pathways limiting
global warming to below 2°C(high confidence).The economic literature distinguishes marginal abatement costs from total
mitigation costs in the economy.The literature on total mitigation costs of 1.5°C mitigation pathways is limited and was
not assessed in this Report. Knowledge gaps remain in the integrated assessment of the economy-wide costs and benefits
of mitigation in line with pathways limiting warming to 1.5°C.{2.5.2;2.6;Figure 2.26}
16 The projected land-use changes presented are not deployed ro tl�elr upper Ilmits simultaneously In a single patl�v✓dy.
17 Induding two pa�hways Ilmiting warming ro 1.5°C witl�no or Ilmlted overshoot and four pathv✓d;rs witl�hlgher overshoot.
18
Summary for Policymakers
C.3 All pathways that limit global warming to 1.5°C with limited or no overshoot project the use of
carbon dioxide removal (CDR) on the order of 100-1000 GtCO, over the 21st century. CDR would
be used to compensate for residual emissions and, in most cases, achieve net negative emissions
to return global warming to 1.5°C following a peak(high confidence). CDR deployment of several
hundreds of GtCO,is subject to multiple feasibility and sustainability constraints(high confidence).
Significant near-term emissions reductions and measures to lower energy and land demand can
limit CDR deployment to a few hundred GtCO,without reliance on bioenergy with carbon capture
and storage(BECCS)(high confidence).{2.3, 2.4, 3.6.2,4.3, 5.4}
C.3.1 Existing and potential CDR measures indude afforestation and reforestation,land restoration and soil carbon sequestration,
BECCS,direct air carbon wpture and storage (DACCS),enhanced weathering and ocean alkalinization.These differ widely
in terms of maturiry, potentials, costs, risks, co-benefits and trade-offs (high confidence). To date, only a few published
pathways indude CDR measures other than afforestation and BECCS.{2.3.4,3.6.2,4.3.2,4.3J}
C.3.2 In pathways limiting global warming to 1.5°C with limited or no overshoot,BECCS deployment is projected to range from
0-1, 0-8, and �16 GtCO, yr ' in 2030, 2050, and 2100, respectively,while agriculture, forestry and land-use (AFOLU)
related CDR measures are projected to remove 0-5, 1-11, and 1-5 GtCO, yr ' in these years (medium confidence).The
upper end of these deployment ranges by mid-century exceeds the BECCS potential of up to 5 GtCO,yr' and afforestation
potential of up to 3.6 GtCO,yr ' assessed based on recent literature (medium confidence). Some pathways avoid BECCS
deployment completely through demand-side measures and greater reliance on AFOLU-related CDR measures (medium
confidence).The use of bioenergy can be as high or even higher when BECCS is exduded compared to when it is induded
due to its potential for replacing fossil fuels across sectors (high confidence). (Figure SPM.3b) {2.3.3,2.3.4, 2.4.2, 3.6.2,
4.3.1,4.2.3,4.3.2,4.3.7,4.4.3,Table 2.4}
C.3.3 Pathways that overshoot 1.5°C of global warming rely on CDR exceeding residual CO3 emissions later in the century to
return to below 1.5°C by 2100,with larger overshoots requiring greater amounts of CDR(Figure SPM.3b)(high confidence).
Limitations on the speed,scale,and societal acceptabiliry of CDR deployment hence determine the abiliry to return global
warming to below 1.5°C following an overshoot Carbon ryde and dimate system understanding is still limited about the
effectiveness of net negative emissions to reduce temperatures after they peak (high confidence). {2.2,2.3.4,2.3.5,2.6,
4.3.7,4.5.2,Table 4.11}
C.3.4 Most current and potential CDR measures could have significant impacts on land,energy,water or nutrients if deployed
at large scale (high confidence).Afforestation and bioenergy may compete with other land uses and may have significant
impacts on agricultural and food systems, biodiversiry, and other ecosystem functions and services (high confidence).
Effective governance is needed to limit such trade-offs and ensure permanence of carbon removal in terrestrial,geological
and ocean reservoirs(high confidence).Feasibiliry and sustainabiliry of CDR use could be enhanced by a portfolio of options
deployed at substantial,but lesser scales,rather than a single option at very large scale(high confidence).(Figure SPM.3b)
{2.3.4,2.4.4,2.5.3,2.6,3.6.2,4.3.2,4.3J,4.5.2,5.4.1,5.4.2;Cross-Chapter Boxes 7 and 8 in Chapter 3,Table 4.11,Table
5.3,Figure 5.3}
C.35 SomeAFOLU-related CDR measures such as restoration of natural ecosystems and soil carbon sequestration could provide
co-benefits such as improved biodiversity, soil quality, and local food security. If deployed at large scale, they would
require governance systems enabling sustainable land management to conserve and protect land carbon stocks and other
ecosystem functions and services(medium confidence).(Figure SPM.4){2.3.3,2.3.4,2.4.2,2.4.4,3.6.2,5.4.1,Cross-Chapter
Boxes 3 in Chapter 1 and 7 in Chapter 3,4.3.2,4.3J,4.4.1,4.5.2,Table 2.4}
19
D. Strengthening the Global Response in the Context of Sustainable
Development and Efforts to Eradicate Poverty
D.1 Estimates of the global emissions outcome of current nationally stated mitigation ambitions as
submitted under the Paris Agreement would lead to global greenhouse gas emissions�s in 2030
of 52-58 GtCO,eq yr ' (medium confidence). Pathways refleding these ambitions would not limit
global warming to 1.5°C, even if supplemented by very challenging increases in the scale and
ambition of emissions reductions after 2030 (high confidence). Avoiding overshoot and reliance
on future large-scale deployment of carbon dioxide removal (CDR) can only be achieved if global
CO, emissions start to dedine well before 2030 (high confidence).{1.2, 2.3, 3.3, 3.4,4.2,4.4, Cross-
Chapter Box 11 in Chapter 4}
D.1.1 Pathways that limit global warming to 1.5°C with no or limited overshoot show clear emission reductions by 2030 (high
confidence).All but one show a dedine in global greenhouse gas emissions to below 35 GtCO,eq yr ' in 2030,and half of
available pathways fall within the 25-30 GtCO,eq yr ' range (interquartile range),a 40-50% reduction from 2010 levels
(high confidence). Pathways reflecting current nationally stated mitigation ambition until 2030 are broadly consistent
with cost-effective pathways that result in a global warming of about 3°C by 2100,with warming continuing afterwards
(medium confidence).{2.3.3,2.3.5,Cross-Chapter Box 11 in Chapter 4,5.5.3.2}
D.1.2 Overshoot trajectories result in higher impacts and associated challenges compared to pathways that limit global warming
to 1.5°C with no or limited overshoot (high confidence). Reversing warming after an overshoot of 0.2°C or larger during
this century would require upscaling and deployment of CDR at rates and volumes that might not be achievable given
considerable implementation challenges(medium confidence).{1.3.3,2.3.4,2.3.5,2.5.1,3.3,4.3J,Cross-Chapter Box 8 in
Chapter 3,Cross-Chapter Box 11 in Chapter 4}
D.1.3 The lower the emissions in 2030,the lower the challenge in limiting global warming to 1.5°C after 2030 with no or limited
overshoot(high confidence).The challenges from delayed actions to reduce greenhouse gas emissions indude the risk of
cost escalation,lock-in in carbon-emitting infrastructure,stranded assets,and reduced flexibility in future response options
in the medium to long term (high confidence). These may increase uneven distributional impacts between countries at
different stages of development(medium confidence).{2.3.5,4.4.5,5.4.2}
D.2 Theavoidedclimatechangeimpactsonsustainabledevelopment,eradicationofpovertyandreducing
inequalities would be greater if global warming were limited to 1.5°C rather than 2°C, if mitigation
and adaptation synergies are maximized while trade-offs are minimized (high confidence).{1.1, 1.4,
2.5,3.3,3.4, 5.2,Table 5.1}
D.2.1 Climate change impacts and responses are dosely linked to sustainable development which balances social well-being,
economic prosperity and environmental protection.The United Nations Sustainable Development Goals(SDGs),adopted in
2015,provide an established framework for assessing the links between global warming of 1.5°C or 2°C and development
goals that indude poverry eradiwtion,reducing inequalities,and dimate action.(high confidence){Cross-Chapter Box 4 in
Chapter 1,1.4,5.1}
D.2.2 The consideration of ethics and equiry can help address the uneven distribution of adverse impacts associated with
1.5°C and higher levels of global warming, as well as those from mitigation and adaptation, particularly for poor and
disadvantaged populations, in all societies (high confidence). {1.1.1, 1.1.2, 1.4.3, 2.5.3, 3.4.10, 5.1, 5.2, 5.3. 5.4, Cross-
Chapter Box 4 in Chapter 1,Cross-Chapter Boxes 6 and 8 in Chapter 3,and Cross-Chapter Box 12 in Chapter 5}
D.2.3 Mitigationandadaptationconsistentwithlimitingglobalwarmingto1.5°Careunderpinnedbyenablingconditions,assessed
in this Report across the geophysical, environmental-ecological, technological, economic, socio-cultural and institutional
18 GHG emissions have been aggregated with 100-year GWP vdlues as'mtmduced In tl�e I PCC Semnd Pssessment Report.
20
Summary for Policymakers
dimensions of feasibility. Strengthened multilevel governance, institutional capacity, policy instruments, technological
innovation and transfer and mobilization of finance,and changes in human behaviour and lifestyles are enabling conditions
that enhance the feasibiliry of mitigation and adaptation options for 1.5°Gconsistent systems transitions.(high confidence)
{1.4,Cross-Chapter Box 3 in Chapter 1,2.5.1,4.4,4.5,5.6}
D.3 Adaptation options specific to national contexts, if carefully selected together with enabling
conditions, will have benefits for sustainable development and poverty reduction with global
warming of 1.5°C,although trade-offs are possible(high confidence).{1.4,4.3,4.5}
D.3.1 Adaptation options that reduce the vulnerability of human and natural systems have many synergies with sustainable
development, if well managed, such as ensuring food and water security, reducing disaster risks, improving health
conditions, maintaining ecosystem services and reducing poverry and inequaliry (high confidence). Increasing investment
in physiwl and social infrastructure is a key enabling condition to enhance the resilience and the adaptive wpacities
of societies. These benefits can occur in most regions with adaptation to 1.5°C of global warming (high confidence).
{1.4.3,4.2.2,4.3.1,4.3.2,4.3.3,4.3.5,4.4.1,4.4.3,4.5.3,5.3.1,5.3.2}
D.3.2 Adaptation to 1.5°C global warming can also result in trade-offs or maladaptations with adverse impacts for sustainable
development. For example, if poorly designed or implemented, adaptation projects in a range of sectors can increase
greenhouse gas emissions and water use,increase gender and social inequaliry,undermine health conditions,and encroach
on natural ecosystems (high confidence).These trade-offs wn be reduced by adaptations that indude attention to poverry
and sustainable development(high confidence).{4.3.2,4.3.3,4.5.4,5.3.2;Cross-Chapter Boxes 6 and 7 in Chapter 3}
D.3.3 A mix of adaptation and mitigation options to limit global warming to 1.5°C,implemented in a participatory and integrated
manner,can enable rapid,systemic transitions in urban and rural areas (high confidence).These are most effective when
aligned with economic and sustainable development,and when local and regional governments and decision makers are
supported by national governments(medium confidence).{4.3.2,4.3.3,4.4.1,4.4.2}
D.3.4 Adaptation options that also mitigate emissions can provide synergies and cost savings in most sectors and system
transitions, such as when land management reduces emissions and disaster risk,or when low-carbon buildings are also
designed for efficient cooling. Trade-offs between mitigation and adaptation, when limiting global warming to 1.5°C,
such as when bioenergy crops, reforestation or afforestation encroach on land needed for agricultural adaptation, can
undermine food securiry,livelihoods,ecosystem functions and services and other aspects of sustainable development.(high
confidence){3.4.3,4.3.2,4.3.4,4.4.1,4.5.2,4.5.3,4.5.4}
D.4 Mitigation options consistent with 1.5°C pathways are associated with multiple synergies and trade-
offs across the Sustainable Development Goals(SDGs).While the total number of possible synergies
exceeds the number of trade-offs,their net effect will depend on the pace and magnitude of changes,
the composition of the mitigation portfolio and the management of the transition.(high confidence)
(Figure SPM.4){2.5,4.5, 5.4}
D.4.1 1.5°C pathways have robust synergies particularly for the SDGs 3 (health),7(dean energy),11 (cities and communities),12
(responsible consumption and production) and 14 (oceans) (very high confidence).Some 1.5°C pathways show potential
trade-offs with mitigation for SDGs 1 (poverry),2 (hunger),6(water)and 7 (energy access),if not managed carefully(high
confidence).(Figure SPM.4){5.4.2;Figure 5.4,Cross-Chapter Boxes 7 and 8 in Chapter 3}
D.4.2 1.5°C pathways that indude low energy demand (e.g.,see P1 in Figure SPM.3a and SPM.3b), low material consumption,
and low GHG-intensive food consumption have the most pronounced synergies and the lowest number of trade-offs with
respect to sustainable development and the SDGs(high confidence).Such pathways would reduce dependence on CDR. In
modelled pathways,sustainable development,eradicating poverty and reducing inequality can support limiting warming to
1.5°C(high confidence). (Figure SPM.3b,Figure SPM.4){2.4.3,2.5.1,2.5.3,Figure 2.4,Figure 2.28,5.4.1,5.4.2,Figure 5.4}
21
Summary for Policymakers
Indicative linkages between mitigation options and sustainable
development using SDGs (rne unkage5 do not 5now�o5t5 and nenefit5)
Mitigation options deployed in each sector can be associated with potential positive effects(synergies)or
negative effects(trade-offs)with the Sustainable Development Goals(SDGs).The degree to which this
potential is realized will depend on the selected portfolio of mitigation options,mitigation policy design,
and local circumstances and context. Particularly in the energy-demand sector,the potential for synergies is
larger than for trade-offs.The bars group individually assessed options by level of confidence and take into
account the relative strength of the assessed mitigation-SDG connections.
Length shows strength of connection Shades show level of confidence
; Theoverallsizeofthemlouretlbarsdepicttherelative Theshadesdepictthelevelofmnfitlenmofthe
I potentialforrynergiesandVadeoffsbetweenthesectoral j�� aseuedpotentialforTraEe-oRs/SYnergies.
; mitigationop[ionsandtheSDGs.
� ' ��
veyrgn mw
Energy Supply Energy Demand Land
Trade-offs Synergies Trade-offs Synergies Trade-offs Synergies
SDG1
No Poverty
SDG] � '1 � '� � '�
Zero Hunger
SDG3
Good Heakh� � •. � •� � •�
and Well-being
SDG4
Quality �
Education� ;� ;� ;�
SDGS
Gender� I� II � �❑ I
Equality e I
SDGfi � I■ � I. � ■ I
CleanWater�
and Sanitation
SDG] }�p�II
Affordableand �- � ',� 1� ',❑
Clean Energy
SDGB
DecentWork� � '� � '� � '�
and Emnomic
Grow[h
SDG9 � I� I. � I�
Industry,
Innovation and
Infrastmcture
SDG 30
Reduced� II � 11 I�
Inequalities
SDG 11 �' �� �'
Sustainable
Citiesand
Communities •
SDG12� �. � �■ ��
Responsible
Consumption ��
and Production ;
SDG 14
Life Below� � '1 � '�
Water
SDG 15
LifeonLand ❑n •1 � •� � :�
SDGlfi� i� I� � I� � I�
Peace,Jus[ice
andStrong
Institutions
SDG 1]
Partnershipsfor `,�,� I' �� � I�
the6oals
22
Summary for Policymakers
Figure5PM.4� Potentlalrynerglesandtrade-offsbetweenthesectoralportfolloofdlmatechangemltlgatlonoptlonsandtheSustalnableDevelopmentGoals
(SDGs).The SDGs serve as an analtical framework for the assessment of the dlfferent sustalnable development dlmensions,whlch eetend beyond the tlme frame
of the 2030 SDG targets.The assessment Is based on Ilterature on mltlgatlon optlons that are cpnsidered relevant for 1.5°C.The assessed strength of the SDG
'mteractlons Is based on the qualltative and quantltatNe assessment of Indlvidual mltlgatlon optlons Ilsted In Table 5.2.Por each mltlgatlon optlon,the strength of
the SDG-cpnnectlon aswell as the associated cpnfidence of the undedying Ilterature(shades of green and red)was assessed.The strength of positive cpnnectlons
(rynergles)and negative mnnectlons(trade-offs)across all IndMldual optlonswithln a sector(seeTable 5.2)are aggregated'mto sectoral potentlals forthewhole
mltlgatlon portfollo.The(whlte)areas outside the bars,whlch Indlcate no'mteractlons,have lowmnfidenw due to the uncerta'mTy and Ilmlted number of studles
eeploring Indlrect effects.The strength of the mnnectlon cpnsiders only the effect of mltlgatlon and does not'mdude benefits of avolded Impacts.SDG B(dlmate
actlon)Is not Ilsted because mltlgatlon Is being cpnsidered'm terms of'mteractlonswith SDGs and notviceversa.The bars denote the strength of the mnnectlon,
and do not cpnsiderthe strength of the Impact on the SDGs.The energy demand sector cpmprises behavioural responses,fuel switching and efficiency optlons In
the transport,Industry and bullding sector aswell as carbon capture optlons'm the Industry sector Optlons assessed'm the energy supply sector cpm prise blomass
and non-blomass renewables,nudear,carbon capture and storage(CCS)with bloenergy,and CCSwith fossil fuels.Optlons'm the land sector mmprise agrialtural
and forest optlons,sustalnable dlets and reduced food waste,soll sequestratlon, Ilvestock and manure management,reduced deforestatlon,afforestatlon and
reforestatlon,and responsible sourcing.In addltlon to thls figure,optlons'm the ocean sector are dlsassed'm the undedying report.[5.4,Table 5.2,Flgure 5.2]
Informatlon about the net Impacts of mltlgatlon on sustalnable development In 1.5°C pathways Is avallable onlyfor a Ilmlted number of SDGs and mltlgatlon
optlons. Only a Ilmlted number of studles have assessed the benefits of avolded dlmate change Impacts of 1.5°C pathways for the SDGs,and the cpeffects
of adaptatlon for mltlgatlon and the SDGs.The assessment of the IndlcatMe mltlgatlon potentlals'm Flgure SPM.4 Is a step further from ARS towards a more
cpmprehensMe and'mtegrated assessment'm the future.
D.4.3 1.5°C and 2°C modelled pathways often rely on the deployment of large-scale land-related measures like afforestation
and bioenergy supply,which,if poorly managed,can compete with food production and hence raise food security concerns
(high confidence).The impacts of wrbon dioxide removal (CDR) options on SDGs depend on the rype of options and the
scale of deployment(high confidence). If poorly implemented,CDR options such as BECCS and AFOLU options would lead
to trade-offs. Context-relevant design and implementation requires considering people's needs, biodiversiry, and other
sustainable development dimensions(very high confidence). (Figure SPM.4){5.4.1.3,Cross-Chapter Box 7 in Chapter 3}
D.4.4 Mitigation consistent with 1.5°C pathways creates risks for sustainable development in regions with high dependenry on
fossil fuels for revenue and employment generation(high confidence).Policies that promote diversification of the economy
and the energy sector can address the associated challenges(high confidence).{5.4.1.2,Box 5.2}
D.4.5 Redistributive policies across sectors and populations that shield the poor and vulnerable can resolve trade-offs for a range
of SDGs,particularly hunger,poverty and energy access.Investment needs for such complementary policies are only a small
fraction of the overall mitigation investments in 1.5°C pathways. (high confidence){2.4.3,5.4.2,Figure 5.5}
D.5 Limiting the risks from global warming of 1.5°C in the context of sustainable development and
poverty eradication implies system transitions that can be enabled by an increase of adaptation
and mitigation investments, policy instruments, the acceleration of technological innovation and
behaviour changes(high confidence).{2.3,2.4, 2.5, 3.2,4.2,4.4,4.5, 5.2, 5.5, 5.6}
D.5.1 Directing finance towards investment in infrastructure for mitigation and adaptation could provide additional resources.
This could involve the mobilization of private funds by institutional investors, asset managers and development or
investment banks,as well as the provision of public funds. Government policies that lower the risk of low-emission and
adaptation investments wn facilitate the mobilization of private funds and enhance the effectiveness of other public
policies.Studies indicate a number of challenges,induding access to finance and mobilization of funds. (high confidence)
{2.5.1,2.5.2,4.4.5}
D.5.2 Adaptation finance consistent with global warming of 1.5°C is difficult to quantiTy and compare with 2°C. Knowledge
gaps indude insufficient data to calculate specific dimate resilience-enhancing investments from the provision of currently
underinvested basic infrastructure.Estimates of the costs of adaptation might be lower at global warming of 1.5°C than for
2°C.Adaptation needs have rypically been supported by public sector sources such as national and subnational government
budgets,and in developing countries together with support from development assistance,multilateral development banks,
and United Nations Framework Convention on Climate Change channels (medium confidence). More recently there is a
23
Summary for Policymakers
growing understanding of the scale and increase in non-governmental organizations and private funding in some regions
(medium confidence). Barriers indude the scale of adaptation financing,limited wpaciry and access to adaptation finance
(medium confidence).{4.4.5,4.6}
D.5.3 Global model pathways limiting global warming to 1.5°C are projected to involve the annual average investment needs
in the energy system of around 2.4 trillion USD2010 between 2016 and 2035, representing about 2.5%of the world GDP
(medium confidence).{4.4.5,Box 4.8}
D.5.4 Policy tools can help mobilize incremental resources, including through shifting global investments and savings and
through market and non-market based instruments as well as accompanying measures to secure the equiry of the
transition, acknowledging the challenges related with implementation, including those of energy costs, depreciation of
assets and impacts on international competition,and utilizing the opportunities to maximize co-benefits(high confidence).
{1.3.3,2.3.4,2.3.5,2.5.1,2.5.2,Cross-Chapter Box 8 in Chapter 3,Cross-Chapter Box 11 in Chapter 4,4.4.5,5.5.2}
D.5.5 The systems transitions consistent with adapting to and limiting global warming to 1.5°C include the widespread adoption
of new and possibly disruptive technologies and practices and enhanced dimate-driven innovation.These imply enhanced
technological innovation capabilities,including in industry and finance. Both national innovation policies and international
cooperation can contribute to the development,commercialization and widespread adoption of mitigation and adaptation
technologies. Innovation policies may be more effective when they combine public support for research and development
with poliry mixes that provide incentives for technology diffusion. (high confidence){4.4.4,4.4.5}.
D.5.6 Education,information,and communiry approaches,induding those that are informed by indigenous knowledge and local
knowledge,can accelerate the wide-scale behaviour changes consistentwith adapting to and limiting global warming to
1.5°C.These approaches are more effective when combined with other policies and tailored to the motivations,capabilities
and resources of specific actors and contexts(high confidence).Public acceptabiliry can enable or inhibit the implementation
of policies and measures to limit global warming to 1.5°C and to adapt to the consequences. Public acceptabiliry depends
on the individual's evaluation of expected poliry consequences, the perceived fairness of the distribution of these
consequences,and perceived fairness of decision procedures(high confidence).{1.1,1.5,4.3.5,4.4.1,4.4.3,Box 4.3,5.5.3,
5.6.5}
D.6 Sustainable development supports, and often enables, the fundamental societal and systems
transitions and transformations that help limit global warming to 1.5°C. Such changes facilitate the
pursuit of climate-resilient development pathways that achieve ambitious mitigation and adaptation
in conjunction with poverty eradication and efforts to reduce inequalities(high confidence).{Box 1.1,
1.4.3, Figure 5.1, 5.5.3, Box 5.3}
D.6.1 Social justice and equiry are core aspects of dimate-resilient development pathways that aim to limit global warming to
1.5°C as they address challenges and inevitable trade-offs,widen opportunities,and ensure that options,visions,and values
are deliberated, between and within countries and communities,without making the poor and disadvantaged worse off
(high confidence).{5.5.2,5.5.3,Box 5.3,Figure 5.1,Figure 5.6,Cross-Chapter Boxes 12 and 13 in Chapter 5}
D.6.2 The potential for dimate-resilient development pathways differs between and within regions and nations,due to different
development contexts and systemic vulnerabilities (very high confidence). Efforts along such pathways to date have been
limited (medium confidence) and enhanced efforts would involve strengthened and timely action from all countries and
non-state actors(high confidence).{5.5.1,5.5.3,Figure 5.1}
D.6.3 Pathways that are consistent with sustainable development show fewer mitigation and adaptation challenges and are
associated with lower mitigation costs.The large majority of modelling studies could not construct pathways characterized
by lack of international cooperation, inequaliry and poverry that were able to limit global warming to 1.5°C. (high
confidence){2.3.1,2.5.1,2.5.3,5.5.2}
24
Summary for Policymakers
D.7 Strengthening the capacities for climate action of national and sub-national authorities,civil society,
the private sector, indigenous peoples and local communities can support the implementation of
ambitious actions implied by limiting global warming to 1.5°C (high confidence). International
cooperation can provide an enabling environment for this to be achieved in all countries and for all
people, in the context of sustainable development. International cooperation is a critical enabler for
developing countries and vulnerable regions(high confidence).{1.4,2.3,2.5,4.2,4.4,4.5,5.3,5.4, 5.5,
5.6, 5, Box 4.1, Box 4.2, Box 4.7, Box 5.3, Cross-Chapter Box 9 in Chapter 4, Cross-Chapter Box 13 in
Chapter 5}
D.7.1 Partnerships involving non-state public and private actors, institutional investors, the banking system, civil society and
scientific institutions would facilitate actions and responses consistent with limiting global warming to 1.5°C (very high
confidence).{1.4,4.4.1,4.2.2,4.4.3,4.4.5,4.5.3,5.4.1,5.6.2,Box 5.3}.
DJ.2 Cooperation on strengthened accountable multilevel governance that indudes non-state actors such as industry, civil
sociery and scientific institutions, coordinated sectoral and cross-sectoral policies at various governance levels, gender-
sensitive policies, finance induding innovative financing, and cooperation on technology development and transfer can
ensure participation,transparenry,capaciry building and learning among different players (high confidence).{2.5.1,2.5.2,
4.2.2,4.4.1,4.4.2,4.4.3,4.4.4,4.4.5,4.5.3,Cross-Chapter Box 9 in Chapter 4,5.3.1,5.5.3,Cross-Chapter Box 13 in Chapter
5,5.6.1,5.63}
DJ.3 International cooperation is a critical enabler for developing countries and vulnerable regions to strengthen their action for
the implementation of 1.5°Gconsistent dimate responses,induding through enhancing access to finance and technology
and enhancing domestic capacities, taking into account national and local circumstances and needs (high confidence).
{2.3.1,2.5.1,4.4.1,4.4.2,4.4.4,4.4.5,5.4.1 5.5.3,5.6.1,Box4.1,Box4.2,Box4.7}.
DJA Collective efforts at all levels,in ways that reflect different circumstances and capabilities,in the pursuit of limiting global
warming to 1.5°C,taking into account equiry as well as effectiveness,can facilitate strengthening the global response to
dimate change,achieving sustainable development and eradicating poverty (high confidence). {1.4.2,2.3.1,2.5.1,2.5.2,
2.5.3,4.2.2,4.4.1,4.4.2,4.4.3,4.4.4,4.4.5,4.5.3,5.3.1,5.4.1,5.5.3,5.6.1,5.6.2,5.6.3}
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Summary for Policymakers
Box SPM.1: Core Concepts Central to this Special Report
Global mean surface temperature (GMST): Estimated global average of near-surface air temperatures over land and
sea ice,and sea surface temperatures over ice-free ocean regions,with changes normally expressed as departures from a
value over a specified reference period.When estimating changes in GMST,near-surface air temperature over both land
and oceans are also used.19{1.2.1.1}
Pre-industrial:The multi-century period prior to the onset of large-scale industrial activity around 1750.The reference
period 185�1900 is used to approximate pre-industrial GMST.{1.2.1.2}
Global warming:The estimated increase in GMST averaged over a 30-year period,or the 30-year period centred on a
particular year or dewde,expressed relative to pre-industrial levels unless otherwise specified. For 30-year periods that
span past and future years,the current multi-decadal warming trend is assumed to continue.{1.2.1}
Net zero CO3 emissions: Net zero carbon dioxide(CO3)emissions are achieved when anthropogenic CO3 emissions are
balanced globally by anthropogenic CO3 removals over a specified period.
Carbon dioxide removal (CDR):Anthropogenic activities removing CO3 from the atmosphere and durably storing it in
geological,terrestrial,or ocean reservoirs,or in products. It includes existing and potential anthropogenic enhancement of
biological or geochemical sinks and direct air capture and storage,but exdudes natural CO3 uptake not directly caused by
human activities.
Total carbon budget: Estimated cumulative net global anthropogenic CO3 emissions from the pre-industrial period
to the time that anthropogenic CO3 emissions reach net zero that would result,at some probabiliry, in limiting global
warming to a given level,accounting for the impact of other anthropogenic emissions.{2.2.2}
Remaining carbon budget:Estimated cumulative net global anthropogenic CO3 emissions from a given start date to the
time that anthropogenic CO3 emissions reach net zero thatwould result,at some probabiliry,in limiting global warming
to a given level,accounting for the impact of other anthropogenic emissions.{2.2.2}
Temperature overshoot:The temporary exceedance of a specified level of global warming.
Emission pathways:In this Summary for Policymakers,the modelled trajectories of global anthropogenic emissions over
the 21 st century are termed emission pathways. Emission pathways are dassified by their temperature trajectory over
the 21 st century: pathways giving at least 50% probability based on current knowledge of limiting global warming to
below 1.5°C are dassified as'no overshooY;those limiting warming to below 1.6°C and returning to 1.5°C by 2100 are
dassified as'1.5°C limited-overshooY;while those exceeding 1.6°C but still returning to 1.5°C by 2100 are dassified as
'higher-overshooY.
Impacts: Effects of dimate change on human and natural systems. Impacts can have beneficial or adverse outcomes
for livelihoods,health and well-being,ecosystems and species,services,infrastructure,and economic,social and cultural
assets.
Risk: The potential for adverse consequences from a dimate-related hazard for human and natural systems, resulting
from the interactions between the hazard and the vulnerabiliry and exposure of the affected system. Risk integrates
the likelihood of exposure to a hazard and the magnitude of its impact. Risk also can describe the potential for adverse
consequences of adaptation or mitigation responses to dimate change.
Climate-resilient development pathways (CRDPs):Trajectories that strengthen sustainable development at multiple
scales and efforts to eradicate poverry through equitable societal and systems transitions and transformations while
reducing the threat of dimate change through ambitious mitigation,adaptation and dimate resilience.
19 Past I PCC reports,reHectlng tl�e Ilteamre,have used a vdriery of appmximately equivdlent metrics of GMA change.
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