Summary for Policy Makers

Table of Contents
Introduction
Box SPM 1: Definitions central to SR 1.5
A. Understanding global warming of 1.5°C
B. Projected climatic changes, their potential impacts and associated risks at 1.5°C
global warming
C. Emission pathways and system transitions consistent with 1.5°C global warming
D. Strengthening the global response in the context of sustainable development and
efforts to eradicate poverty

Introduction
This report responds to the UN Framework Convention on Climate Change’s invitation to the
IPCC in December 2015 “…to prepare 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”. The IPCC accepted this invitation in April 2016, deciding to prepare this report in
the context of strengthening the global response to the threat of climate change, sustainable
development, and efforts to eradicate poverty.
This Special Report assesses literature [1] relevant to all three IPCC Working Groups and
uses the IPCC methodologies and calibrated language for communicating certainty in key
findings [2].
The Summary for Policy Makers is structured into four sections: Section A, Understanding
global warming of 1.5°C; Section B, Projected climatic changes, their potential impacts and
associated risks at 1.5°C global warming; Section C, Emissions pathways and system
transitions consistent with 1.5°C global warming; and Section D, Strengthening the global
response in the context of sustainable development and efforts to eradicate poverty.
Its narrative is support by headline statements that taken together, provide an overview of
the key findings. The underlying scientific basis for each paragraph can be traced to the
chapter sections of the report as indicated by the references provided.

Box SPM 1: Definitions central to SR1.5
Global mean surface temperature (GMST): Area-weighted global average of land surface
air temperature and sea surface temperatures, unless otherwise specified, normally
expressed relative to a specified reference period.
Global warming: An increase in GMST averaged over a 30-year period, relative to 18501900 unless otherwise specified. For periods shorter than 30 years, global warming refers to

 the estimated average temperature over the 30 years centred on that shorter period,
accounting for the impact of any temperature fluctuations or trend within those 30 years.

Pre-industrial: The multi-century period prior to the onset of large-scale industrial activity.
The reference period 1850-1900 is used to approximate pre-industrial GMST in this report.
1.5°C or 2°C warmer worlds: Projected worlds in which global warming has reached and,
unless otherwise indicated, been limited to 1.5°C or 2°C above pre-industrial levels.
Net-zero CO2 emissions: Conditions in which any remaining anthropogenic carbon dioxide
(CO2) emissions are balanced globally by anthropogenic CO2 removals. Net-zero CO2
emissions are also referred to as carbon neutrality.
Remaining carbon budget: Cumulative global CO2 emissions from the start of 2018 to the
time that CO2 emissions reach net-zero that would result in a given level of global warming.
Overshoot: The temporary exceedance of a specified level of global warming, such as
1.5°C. Overshoot implies a peak followed by a decline in global warming, achieved through
anthropogenic removal of CO2 exceeding remaining CO2 emissions globally.
1.5°C-consistent pathway: A pathway of emission of greenhouse gases and other climate
forcers that provides and approximately one-in-two or two-in-three chance, given current
knowledge of the climate response, of global warming either remaining below 1.5°C or
returning to 1.5°C by around 2100 following an overshoot.
Impacts: Effects of climate change, such as warming, sea level rise or changes in the
frequency and intensity of heat waves, on human and natural systems. Impacts can have
positive or negative outcomes for lives, livelihoods, health and wellbeing, ecosystems and
species, economic, social and cultural assets, services and infrastructure.
Risk: The potential for adverse consequences from a climate-related hazard for human and
natural systems, resulting from the interactions between the hazard and the vulnerability and
exposure of the affected system. Risk can also include the uncertain adverse outcomes of
adaptation or mitigation responses.
Enabling conditions: Factors, including governance, policy, finance, behaviour, innovation
and capacity, that can facilitate the global response to climate change and that underpin the
feasibility of mitigation and adaptation options, acknowledging synergies and trade-offs
among different options.
A.

Understanding global warming of 1.5°C

A1. Human-induced global warming reached approximately 1±0.2°C (likely range)
above pre-industrial levels in 2017 and is currently increasing at 0.2±0.1°C per decade
(high confidence).
{1.2, Figure SPM1}
A1.1. Observed global average surface temperature for the decade 2006-2015 was 0.87°C
(±0.12°C) [3] warmer than 1850-1900 (very high confidence). Since 2000, the estimatedlevel of human-induced warming has been equal to the level of observed warming with a
likely range of ±20% (high confidence). {1.1.1, Table 1.1}
A1.2. Energy continues to accumulate in the climate system due to past and present
greenhouse gas emissions and other anthropogenic climate forcers (very high confidence),
causing continued warming at a rate of 0.2°C/decade with a likely range of ±0.1°C (high
confidence). {1.21.1, 1.2.4}
A1.3. Warming greater than the global average is being experienced in many regions and
seasons, with average warming greater 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}
A2. Past emissions alone are unlikely to raise GMST to 1.5°C above pre-industrial
levels, but do commit to further changes such as sea-level rise and associated
impacts (high confidence). If emissions continue at their present rate, human-induced
warming will exceed 1.5°C by around 2040 (high confidence). {1.2, 3.3, Figure SPM 1}
A2.1. If all anthropogenic emissions (including greenhouse gases, aerosols and their
precursors) were reduced to zero immediately, it is likely that any further warming would be
less than 0.5°C over the next two to three decades (high confidence), and likely less than
0.5°C on a century time scale (medium confidence), due to the compensating effects of
different climate processes and climate forcers. {1.2.4, Figure 1.6}
A2.2. If emissions continue at their present rate over the coming decades, the present rate
of human –induced warming of 0.2±0.1°C per decade will continue (very high confidence).
{1.2.1, 1.2.4}
A2.3. Stabilising GMST requires net-zero CO2 emissions and declining total radiative forcing
[4] from other anthropogenic forcers (high confidence). The maximum level of warming is
then determined by cumulative CO2 emissions up to the time of net-zero (high confidence)
and the level of non- CO2 radiative forcing in the decades immediately prior to that time
(medium confidence) (Figure SPM 2). {Cross-Chapter Box 2 in Chapter 1, 1.2.3, 1.2.4, 2.2.1,
2.2.2}
A3. Risks for natural and human systems are lower for global warming of 1.5°C than
at 2°C depending on geographic location, levels of development and vulnerability, and
on the choices of adaptation and mitigation options (high confidence) (Figure SPM2).{1.3, 3.3, 3.4, 5.6}

A3.1 Risks for natural and human systems are lower if global warming gradually stabilises at
1.5°C, compared to overshooting 1.5°C and returning later to this level later in the century
(medium confidence). {3.4, Box 3.4, Cross-Chapter Box 8 in Chapter 3}
A4. Sustainable development, poverty eradication and implications for ethics and
equity will be key considerations in mitigation efforts to limit global warming to 1.5°C
and by efforts to adapt to 1.5°C global warming (high confidence). {1.1, 1.4, CrossChapter Box 4 in Chapter 1, 5.2, 5.3}A4.1. The poor and vulnerable are disproportionately affected by many impacts of global
warming as well as the challenges of remaining below global warming of 1.5°C; with
associated mitigation options implying a combination of significant benefits and adverse
effects, depending on the various mitigation options (high confidence). {1.1.1, 1.1.2, 1.4.3,
2.5.3, Cross-Chapter Boxes 4 in Chapter 1, 7 and 8 in Chapter 3 and 13 in Chapter 5}
A4.2. Effective adaptation requires the integration of scientific, technological and social
conditions and capacities. Sustainable development, poverty eradication and reduction of
inequalities are enabled by enhancing local capabilities (high confidence). {4.2.2, 4.4.1,
4.4.3, 4.5.3, 5.3.1}
A4.3. Climate resilient development pathways (CRDPs) are a framework to simultaneously
achieve the goals of emission reduction, climate adaptation and climate resilience in the
context of sustainable development, poverty eradication and reducing inequalities. {1.4.3,
Cross Chapter Box 1, 5.1, 5.5.3}
A5. There is no simple answer to the question of whether it is feasible to limit
warming to 1.5°C and to adapt to the consequences because feasibility has multiple
dimensions that need to be considered simultaneously and systematically. {1.4,
Cross-Chapter Box 3 in Chapter 1, 4.3, 4.4}
A5.1 In the context of sustainable development, feasibility depends on enabling conditions.
These include institutional capacity, policy and finance, multi-level governance, technological
innovation and transfer, and changes in human behavior and lifestyles. Feasibility also
reflects links, positive (synergies) and negative (trade-offs), between sustainable
development, mitigation, and adaptation on multiple scales. {1.4, Cross-Chapter Box 3 in
Chapter 1, 4.4, 5.6}

B. Projected climatic changes, their potential impacts and associated risks at 1.5°C
global warming
B1. There are substantial increases in extremes between the present-day and a global
warming of 1.5°C, and between 1.5°C and 2°C, including hot extremes in all inhabited
regions [5] (high confidence), heavy precipitation events in most regions (high
confidence), and extreme droughts in some regions (medium confidence). {3.3, CrossChapter Box 8 in Chapter 3}
B1.1 Changes in temperature extremes and heavy precipitation indices are detectable in
observations for the 1991-2010 period compared with 1960-1979, a timespan over which
global warming of approximately 0.5°C occurred {3.3.1, 3.3.2, 3.3.3}
B1.2. Temperature extremes on land are projected to warm more than the global average:
extreme hot days in mid-latitudes by a factor of up to 2, i.e. ~3°C at 1.5°C global warming,
and extreme cold nights in high-latitudes by a factor of up to 3, i.e. ~4.5°C at 1.5°C global
warming (high confidence). The number of highly unusual hot days is projected to increase
the most in the tropics (high confidence). {3.3.1, 3.3.2, Cross-Chapter Box 8 in Chapter 3}

 B1.3. Limiting global warming to 1.5°C compared to 2°C reduces the likelihood of increases
in heavy precipitation events in several northern hemisphere high latitude and high elevation
regions (medium confidence). Less land would be affected by flood hazards (medium
confidence) and the probability of extreme droughts would be less in some regions, including
the Mediterranean and southern Africa (medium confidence). {3.3.3, 3.3.4, 3.3.5}
B2. On land, risks of climate-induced impacts on biodiversity and ecosystems,
including species loss and extinction, are substantially less at 1.5°C global warming
than at 2°C. Limiting global warming to 1.5°C has large benefits for terrestrial and
wetland ecosystems and for the preservation of their services (high confidence).
Temperature overshoot, if much higher than 1.5°C (eg. Close to 2°C), could have
irreversible impacts on some species, ecosystems and their ecological functions and
services to humans, even if global warming eventually stabilizes at 1.5°C by 2100
(high confidence). (SPM Figure 2) {3.4, 3.5, Box 3.4, Box 4.2, Cross-Chapter Box 8 in
Chapter 3}
B2.1. The number of species projected to lose over half of their climatically determined
geographic range at 2°C is reduced by a factor of two or more at 1.5°C, i.e. by 50% (plants,
vertebrates) or 66% (insects) (high confidence). Impacts associated with other biodiversityrelated risks such as forest fires, and the spread of invasive species, are also reduced
substantially at 1.5°C compared to 2°C of global warming (high confidence). {3.4.3.2, 3.5.2}
B2.2. The terrestrial area affected by ecosystem transformation (13%) at 2°C is
approximately halved at 1.5°C (high confidence). {3.3.4, 3.4.3.5, 3.4.6.1, 3.5.10, Box 4.2}
B2.3. High-latitude tundra and boreal forests are particularly at risk, with woody shrubs
encroaching into the tundra (high confidence). Limiting global warming to 1.5°C could
prevent the thawing of an estimated permafrost area of 2 million km2 of permafrost area over
centuries (high confidence) {3.3.2, 3.4.3, 3.5.5}
B.3 Due to projected differences in ocean temperature, acidification and oxygen
levels, limiting warming to 1.5°C compared to 2°C would substantially reduce risks to
marine biodiversity, ecosystems and their ecological functions and services to
humans in ocean and coastal areas, especially Arctic sea-ice ecosystems and warm
water coral reefs. {3.3, 3.4, 3.5, Boxes 3.4, 3.5}
B3.1. With 2°C of global warming, it is very likely that there will be at least one sea ice-free
Arctic summer per decade. This is reduced to one per century with 1.5°C global warming.
Effects of an overshoot are reversible for Arctic sea-ice cover (high confidence). {3.3.8,
3.4.4.7}
B3.2. Ocean ecosystems are experiencing large-scale changes with critical thresholds being
exceeded at 1.5°C and above (high confidence) Crossing those thresholds may have
irreversible effects. The majority of warm water coral reefs, for example, are already
experiencing the large scale loss of coral abundance (cover) today and would lose a further
70-90% of cover at 1.5°C global warming (very high confidence). {3.4.4, Box 3.4}

 B3.3. The level of ocean acidification in a 1.5°C warmer world is expected to amplify the
adverse effects of warming, impacting the survival, calcification, growth, development, and
abundance of a broad range of taxonomic groups (ie. From algae to fish) (high confidence).
{3.3.10, 3.4.4}
B3.4. The risk of declining ocean productivity, distributional shifts (to higher latitudes),
damage to ecosystems (eg. Coral reefs, wetlands), loss of fisheries productivity (at low
latitudes), and changing ocean chemistry (e.g., acidification, hypoxia) are projected to be
substantially lower at 1.5°C of global warming, as compared to 2°C (high confidence) {3.4.4,
Box 3.4}
B4. By 2100, sea level rise would be around 0.1m lower with 1.5°C global warming
compared to 2°C (medium confidence). Increased saltwater intrusions, flooding, and
damage to infrastructure associated with increased sea level are especially harmful
for vulnerable environments such as small islands, low-lying coasts, and deltas (high
confidence) {3.3, 3.4, 3.6}
B4.1. Sea level rise will continue beyond 2100 (high confidence). Greenland and/or Antarctic
ice sheet instabilities that could result in multi-metre rise in sea level on centennial to
millennial time scales, may be triggered even if global warming is limited to 1.5°C by 2100
(medium confidence). {3.3.9, 3.4.5, 3.5.2, 3.6.3, Box 3.3}
B4.2 A reduction to global sea level rise of 0.1m at global warming of 1.5°C compared to 2°C
implies that approximately 10 million fewer people are expected to be exposed to related
risks, based on a 2010 population estimate. The slower rate of rise for global warming of
1.5°C is expected to provide substantially greater opportunities for adaptation {3.4.4, 3.4.5,
4.3.2}
B5. Impacts on health, livelihoods, food and water supply, human security,
infrastructure, and the underlying potential for economic growth will increase with
1.5°C of warming compared to today, and even more with 2°C warming compared to
1.5°C. (SPM Figure 2) {3.4, 3.5, 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}
B5.1. Disadvantaged and vulnerable populations and nations will be disproportionately
affected by the impacts of global warming of 1.5°C and beyond (high confidence). This is
particularly the case for Indigenous people and systems in the Arctic, populations dependent
on agriculture – and coastal livelihoods, and small-island developing states, many of which
face limits to adaptation already (medium confidence). {3.4.10, 3.4.11, Box 3.5, CrossChapter Box 6 in Chapter 3, Cross-Chapter Box 11 in Chapter 4, Cross-Chapter Box 12 in
Chapter 5, 5.2.1, 5.2.2, 5.2.3, 5.6.3}
B5.2. While any future increase in global warming will affect human health (high confidence),
risks will be lower at 1.5°C than at 2°C for heat-related morbidity and mortality (very high
confidence). Risks are with increasing warming are particularly high in urban areas due to
the urban heat island effect (high confidence). Risks are projected to increase for some
vector-borne diseases, such as malaria and dengue fever (high confidence). {3.4.7}

 B5.3. Limiting global warming to 1.5°C compared to 2°C would result in a lower global
reduction in crop yields and nutritional quality (high confidence) and lower risks to crop
production in Sub-Saharan Africa (particularly West Africa, southern Africa), South-East Asia,
and Central and South America. Risks of food shortages in the Sahel, southern Africa, the
Mediterranean, central Europe, and the Amazon are significantly lower with 1.5°C of
warming, compared to 2°C. [3.4.6, 3.5.4, 3.5.5, Box 3.1, Cross-Chapter Box 6 in Chapter 3,
4.3.2, 4.3.5, 4.5.3, Box 4.2, Box 4.3, Cross-Chapter Box 9 in Chapter 4}
B5.4. Limiting global warming to 1.5°C compared to 2°C would approximately halve the
proportion of the world population expected to suffer water scarcity, although there is
considerable variability between regions (medium confidence). Many small island developing
states would experience substantially less freshwater stress as a result of projected changes
in aridity 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, 4.3.2, 4.3.3, 4.4.1, 4.4.2, 4.4.5, 4.5.3, CrossChapter Box 9 in Chapter 4)}
B5.5 Impacts of 1.5°C global warming on global economic growth are larger than those of
the present-day, with the largest impacts expected in the tropics and the Southern
Hemisphere subtropics (low confidence). Economic growth is projected to be lower at 2°C
than at 1.5°C of global warming for many developed and developing countries (medium
confidence). {3.5.2, 3.5.3]
B5.6. There are multiple lines of evidence that since AR5 the levels of risk have increased
for four of the five Reasons for Concern (RFCs) for global warming levels of up to 2°C (high
confidence), see Figure SPM2. Constraining warming to 1.5°C reduces the risk of reaching a
“very high” level in RFC1 (unique and threatened systems) (high confidence), and reduces
the risk of reaching a “high” level in RFC3 (Distribution of impacts) (high confidence) and
RFC4 (Global Aggregate Impacts) (medium confidence). It would also reduce risks
associated with RFC2 (Extreme Weather events) and RFC5 (Large scale singular events)
(high confidence) (SPM Figure 2) {3.4.13; 3.5, 3.5.2}
B6. Limits to adaptation and associated losses exist at every level of global warming
(medium confidence) with site-specific implications for vulnerable regions and
populations. Further adaptation is required within the assessed sectors of energy,
land and ecosystems, urban, industrial, and transport systems, and within crosscutting sectors such as disaster risk management, health and education; adaptation
needs will be lower at global of 1.5°C, compared to 2°C.
B6.1. Adaptation opportunities will be reduced and the risks of unavoidable damages
increased (medium confidence) in vulnerable regions, including small island, that are
projected to experience higher multiple inter-related climate risks at 1.5C global warming
compared to today, with risks increasing further with warming of 2°C (high confidence).
{3.3.1, 3.4.5, Box 3.5, 4.4.1, 4.4.3, 4.4.5, 5.6, Cross-Chapter Box 12 in Chapter 5, Box 5.3}
B6.2. Infrastructure investments and innovative mechanisms to target finance towards
adaptation, including transformational approaches, at various scales may alleviate the
impacts of climate at 1.5°C. {4.4.5, 4.5.3}

 B6.3. In energy and industrial systems, options considered feasible for adaptation at global
warming of 1.5°C are water management and cooling strategies and resilience of existing
infrastructure (medium confidence). Adaptation options for land and ecosystems at global
warming of 1.5°C include conservation agriculture, efficient irrigation, efficient livestock,
agroforestry, community-based adaptation, ecosystem restoration and avoided
deforestation, biodiversity management and coastal defence and hardening (high
confidence). Urban adaptation options at global warming of 1.5°C include green
infrastructure, resilient water and urban ecosystem services, urban and per-urban
agriculture, and adapting building and land use through regulation and planning (high
confidence). {4.3.1, 4.3.2, 4.3.3, 4.3.4, 4.5.3}
B6.4. Several overarching adaptation options that are closely linked to sustainable
development can be implemented across rural landscapes, such as investing in health,
social safety nets, and insurance for risk management, or disaster risk-management and
education-based adaptation options. These are being implemented today and can also be
scaled up for 1.5°C of global warming {1.4.3, 4.3.5, 4.5.3}

C. Emission pathways and system transitions consistent with 1.5°C global warming
C1. All 1.5°C-consistent pathways imply rapid reductions in net global anthropogenic
CO2 emissions to reach net-zero around mid-century, together with rapid reductions
in other anthropogenic emissions, particularly methane. Greater emissions
reductions by 2030 lead to a higher chance of limiting global warming to 1.5°C
without, or with only limited overshoot (zero to 0.2°C). (high confidence) (Figures
SPM1 and SPM3) {1.3,1.2,2.2,2.4,2.3,2.5}
C1.1. 1.5°C-consistent pathways differ in the portfolio of measures deployed to achieve
emissions reductions. This results in different implications regarding synergies and trade-offs
with sustainable development, poverty eradication and reducing inequalities. Solar radiation
modification (SRM) measures are not included in any of the available assessed pathways.
Though some may be theoretically effective in reducing an overshoot, SRM measures face
large uncertainties and knowledge gaps as well as substantial institutional and social
constraints to deployment related to governance, ethics, and impacts on sustainable
development (medium confidence). (Figures SPM3 and SPM4) {2.2, 2.4,2.5,4.3,4.3.8,4.5,
Cross-Chapter Box 10 in Chapter 4,5.4.2,5.5.2}
C1.2. The remaining carbon budget for a one-in-two chance of limiting global warming to
1.5°C is about 750 GtCO2, and about 550 GtCO2 for a two-in-three chance (medium
confidence). These remaining budgets are larger than those estimated in AR5 [6]. Estimates
of remaining budgets for 1.5°C vary by more than 50% due to assessed uncertainties in the
climate response to emissions, and by ±250 GtCO2 due to assessed uncertainties in global
warming until the decade 2006-2015. If calculated out to 2100, budgets could be reduced by
up to 100 GtCO2 by permafrost thawing and potential methane release from wetlands
(medium confidence). {2.2.2, 2.6.1, Table 2.2, Technical Annex Chapter 2}

 C1.3. Different amounts of non-CO2 mitigation result in variations in the remaining carbon
budget consistent with 1.5°C ±GtCO2 (medium confidence). In the next two to three decades,
removal of SO2 would add to the future warming, but reductions in methane emissions would
partially compensate (high confidence). However, emissions of N2O increase in some
pathways with high bioenergy demand. (Figures SPM1 and SPM3) {2.2.2, 2.3.1, 2.4.2, 2.5.3}
C1.4 Pathways that aim for no or limited (zero to 0.2°C) overshoot of 1.5°C have substantial
emission reductions by 2030, keeping global GHG emissions [7] in 2030 to 25-30 GtCO2eq/yr
(interquartile range), a 40-50% reduction from 2010. Uncertainties in the climate response
imply the possibility of lower or higher warming levels being reached by these pathways.
(SPM Figure 1) {2.2.1, 2.3.3}
C2. 1.5°C-consistent pathways can have different levels of carbon dioxide removal (CDR).
Some limit global warming to 1.5°C without relying on bioenergy with carbon capture and
storage (BECCS). Behavioral change, demand-side measures and emission reductions in
the short term can limit the dependence on CDR (high confidence). {2.3,2.5,4.3}
C2.1. Different CDR methods exist, with widely differing maturity, potentials, costs and sideeffects. Examples include afforestation and reforestation, BECCS, direct air carbon capture
and storage and soil carbon sequestration. The feasibility of CDR measures relates to their
impacts on sustainable development, and depends on scale, implications for land, water and
energy use (high confidence). Feasibility of CDR could be enhanced by a portfolio of options
deployed at smaller scales, rather than a single option at a large scale (high confidence).
(Figure SPM3) {2.3,2.5.3,2.6,3.6.2,4.3.7,4.5.2,5.4.1,5.4.2; Cross-Chapter Boxes 7 and 8 in
Chapter 3, Table 4.11, Table 5.3, Figure 5.3}.
C2.2. The faster reduction in emissions associated with 1.5°C-consistent pathways
compared to holding warming below 2°C-consistent pathways is predominantly achieved by
measures that result in less CO2 being emitted, and only to a smaller degree through
additional CDR. Pathways that overshoot 1.5°C need to rely on CO2 removal exceeding
remaining CO2 emissions to return global warming to below 1.5°C by 2100 (high
confidence). Geophysical understanding is limited about the effectiveness of CDR to reduce
temperatures after they peak. (Figure SPM3) {2.2, 2.3, 2.6, 4.3.7, 2.5.2, Table 4.11}
C2.3. There is variation in the amount and types of CDR used in 1.5°C-consistent pathways,
suggesting flexibility in addressing implementation challenges (medium confidence). In
1.5°C-consistent pathways, BECCS deployment ranges from 0-9 GtCO2 /yr in 2050, and 016 GtCO2/yr in 2100, while agriculture, forestry and land-use (AFOLU) related CDR
measures remove 0-11 GtCO2/yr in 2050 and 1-5 GtCO2/yr in 2100. Some pathways avoid
BECCS deployment through low energy demand and greater reliance on AFOLU-related
CDR measures. Bioenergy can still be substantial without BECCS due to its cross-sectoral
potential for replacing fossil fuels (high confidence) (Figure SPM3) {2.3.3, 2.3.4, 2.4.2, 3.6.2,
5.4.1, Cross-Chapter Box 7 in Chapter 3, 4.4.3, 4.3.7, Table 2.4}
C2.4. Some AFOLU measures have potential other benefits, for example, improved
biodiversity and soil quality, when combined with policies to conserve and restore land
carbon stocks and protest natural ecosystems (medium confidence). (Figure SPM 4) {2.3.3,
2.3.4, 2.4.2, 3.6.2, 5.4.1, Cross-Chapter Box 7 in Chapter 3, 4.3.2, 4.3.7, 4.5.2, Table 2.4}

 C3 Limiting global warming to 1.5°C would require rapid and far-reaching systems
transitions occurring during the coming one to two decades, in energy, land, urban,
and industrial systems. {2.3, 2.4, 2.5, 4.2, 4.3, 4.5, 5.4}
C3.1. Pathways that are consistent with limiting global warming to 1.5°C are qualitatively
similar to those for 2°C, but their system changes are more rapid and pronounced over the
next decades (high confidence). These rates of change were observed in the past within
specific sectors, technologies and spatial contexts, but there is no documented historic
precedent for the scale found in 1.5°C-consistent pathways. {2.3.3, 2.3.4, 2.4, 2.5, 4.2.2, 4.5}
C3.2. In energy systems, 1.5°C-consistent pathways include a substantial reduction in
energy demand, in a decline in the carbon intensity of electricity to zero by mid-century, and
an increase in electrification of energy use (high confidence). By 2030, the median level of
primary renewable energy (including bioenergy, hydro, wind and solar) in 1.5°C-consistent
pathways increase by 60% compared to 2020, while primary energy from coal decreases by
two-thirds. By 2050, renewables are expected to supply 49-67% of primary energy, while
coal would be expected to supply 1-7%. The political, economic, social and technical
feasibility of solar energy, wind energy and electricity storage technologies increased over
the past few years (high confidence), signaling that such a system transition in electricity
generation may be underway. {2.4.2, 4.2.1, 4.3.1, 4.5.2, Cross-Chapter Box 6 in Chapter 3}
C3.3 Transitions in global and regional land use are required to limit warming to 1.5°C. Such
transitions require integrative policies to sustainably manage competing demands on land for
human settlements, food, livestock, fibre, bioenergy, carbon storage, biodiversity and
ecosystem services. This may include sustainable intensification of land use practices,
enhanced agricultural productivity and diet changes. Such options are often limited by
institutional, environmental and socio-cultural feasibility, though experiences show that these
constraints can be overcome (high confidence). {1.4.2, 2.3.4, 2.4.4, 4.3.2, 4.4.4, 4.4.5, 5.4.2,
5.4.1, Cross-Chapter Boxes 3 in Chapter 1 and 7 in Chapter 3}
C3.4. Emissions from industry in 1.5°C-consistent pathways are about 70-90% lower in 2050
compared to 2010. Energy-intensive industry can achieve these reductions through
combinations of novel technologies and practices, including low-emissions electrification,
hydrogen, bio-based feedstocks, product substitution, and in several cases CCS (high
confidence). Although technically proven, the deployment at scale of these options is limited
by economic feasibility and institutional constraints. Energy efficiency can have a positive
effect (synergy) on a large number of SDGs and is a more economically feasible enabler of
industrial system transitions, though by itself provides insufficient emission reductions in
industry (Figure SPM4) (high confidence). {4.2.1, 4.3.4, 4.5.2, 5.4.1}
C3.5. Transport and buildings, and their associated infrastructure, achieve deep emission
reductions by 2050 in 1.5°C-consistent pathways. Technical measures (such as efficient
appliances, insulation and electrification) and lifestyle choices that lower energy demand or
favour cycling and walking can achieve such deep emissions reductions while enhancing
multiple SDGs. While technological performance can be improved for all these options,
socio-cultural, market, and economic barriers may inhibit rapid and far-reaching change
(high confidence) (Figure SPM4). {2.3.4, 2.4.3, 4.33, 4.4.3, 4.5.2, 4.4.5, 5.4.1, Table 5.3}

 D. Strengthening the global response in the context of sustainable development and
efforts to eradicate poverty
D1. Fulfilling the current pledges under the Paris Agreement (known as NationallyDetermined Contributions or NDCs) will still result in global warming of more than
1.5°C, with associated risks and adaptation challenges. Emissions reductions and
action in addition to current NDCs lead to lower overshoot and lower transitional
challenges after 2030 and can contribute to the achievement of the UN Development
Goals (SDGs) (high confidence) {1.2, 2.3, 3.3, 3.4, 4.2, 4.4, Cross-Chapter Box 11 in
Chapter 4}
D1.1. Implementation of the conditional and unconditional NDCs is projected to result in
global GHG emissions in 2030 of 50-54 GtCO2eq/yr and 52-58 GtCO2eq/yr, respectively
(high confidence). {Cross-Chapter Box 11 in Chapter 4}
D1.2. Collectively meeting the current conditional and unconditional NDCs would imply
pursuing an overshoot trajectory to return global warming to 1.5°C. This would result in
higher impacts and adaptation challenges, higher transitional challenges to reduce GHG
emissions after 2030 and a higher reliance on CDR compared to pathways that are
consistent with limited or no overshoot and which have deeper GHG emissions reductions
until 2030 (high confidence) {1.3.3, 2.3.4, 2.3.5, 2.5.1, Cross-Chapter Box 8 in Chapter 3
and 11 in Chapter 4}
D2. Limiting global warming to 1.5°C in the context of sustainable development and
poverty eradication requires a portfolio of mitigation and adaptation actions that work
across sectors and scales. These actions would face key barriers and are enabled by
change, such as finance, technology and behaviour (high confidence) {2.3, 2.4, 2.5,
3.2, 4.2, 4.4, 4.5, 5.2, 5.5, 5.6}
D2.1. Abatement costs resulting in 1.5°C-consistent pathway modelling are 3-4 times higher,
on average, compared to holding warming to 2°C (high confidence). {2.5.1, 2.5.2, 4.4.5,
5.5.2}
D2.2. Limiting global warming to 1.5°C requires enhanced action by countries and non-state
actors in the next decade. Stringent near-term policies to support the transitions required to
limit global warming to 1.5°C are more effective when integrated policy packages are used,
involving innovative non-price and price instruments. {1.3.3, 2.3.4, 2.3.5, 2.5.1, CrossChapter Box 8 in Chapter 3 and 11 in Chapter 4}
D2.3. Global investments in energy, transportation, buildings, and water and sanitation
infrastructure are higher in most 1.5°C-consistent pathways compared to today, with an
additional 1.7% to 2.5% of annual economy-wide investment required from the present to
2035. Such changes can be enabled by a portfolio of policies and measures, including
pricing instruments, fiscal policies, technology policies, performance standards and
reforming of energy subsidies. In the next two decades, investments in low-carbon energy

 technologies is expected to roughly double in 1.5°C-consistent pathways, while fossil-fuel
extraction decreases by about a quarter (medium confidence). {2.5.2, 4.4.5, Box 4.8}
D2.4. Effective innovation policies combine support for research and development and
incentives for market uptake, as well as on the degree of cooperation between governments
and the private sector. Both national and international innovation policies can contribute to
the commercialization and widespread adoption of new technologies {4.4.4}
D2.5. Public acceptability can enable or inhibit the implementation of policy to limit global
warming to 1.5°C and to adapt to the consequences, and depends on the evaluation and
distribution of expected policy consequences and perceived fairness of decision procedures.
{4.4.3}
D2.6. Education, information and feedback, and community approaches that rely on
Indigenous and local knowledge, when combined with the policies mentioned in D2.3 and
tailored to motivations and circumstances of specific actors and contexts, can accelerate the
wide scale behaviour changes assumed in 1.5°C-consistent pathways to adapt to and limit
global warming to 1.5°C (high confidence). {1.1,1.5, 4.3.5, 4.4.1, 4.4.3, Box 4.3, 5.5.3, 5.6.5}
D3. Adaptation can reduce vulnerability to global warming of 1.5°C and is mostly
beneficial for sustainable development and poverty reduction. There can also be
negative consequences (trade-offs) with some of the UN SDGs if actions are not
context-specific and managed carefully (high confidence). {1.4, 4.5, 5.3}
D3.1. Both incremental and transformational adaptation are needed to reduce vulnerability
with 1.5°C global warming involving deep and long-term societal changes that influence
sustainable development, poverty reduction and foster equity (high confidence). {1.4.3,
4.2.2, 4.4.1, 4.4.3, 4.5.3, 5.3.1}
D3.2. Adaptation options to reduce vulnerability at 1.5°C global warming, have significant
synergies with SDGs for agriculture, health, urban sectors, and ecosystems (high
confidence). Investments in health and social security can be cost effective measures for
adaptation with potential for scaling up (medium confidence). {4.3.3, 4.5.3, 4.5.4, 5.3.2}
D3.3. Agricultural adaptation and securing provision of food security with 1.5°C global
warming can result in trade-offs with seven SDGs, including health and wellbeing, gender
equality, climate action, water, resilient infrastructure, marine and terrestrial ecosystem (high
confidence). {4.3.2, 4.5.4, 5.3.2, Cross-Chapter Boxes 6,7 and 8 in Chapter 3}
D4. Mitigation consistent with 1.5°C global warming pathways is associated with
multiple synergies and trade-offs across a range of UN SDGs, depending on the pace
and magnitude of changes and the management of the transition (high confidence).
(SPM Figure 4) {2.5, 4.5, 5.4}
D4.1. Pathways consistent with 1.5°C global warming indicate robust synergies particularly
for the SDGs 3 (health), 7 (sub goal of clean energy), 11 (cities and communities), 12
(responsible consumption and production), and 14 (oceans (very high confidence). For
SDGs 1 (poverty), 2 (hunger), 6 (water), and 7 (sub-goal of energy access), stringent

 mitigation actions compatible with 1.5°C can have trade-offs or negative side-effects if not
carefully managed (high confidence) (Figures SPM2 and SPM4). {4.3.1, 4.5.2, 5.4.2; Figure
5.4, Cross-Chapter Boxes 7 and 8 in Chapter 3}
D4.2. 1.5°C-consistent pathways that achieve low carbon energy and material consumption,
and low GHG-intensive food consumption have most pronounced synergies and the lowest
number of trade-offs with respect to sustainable development and the SDGs (high
confidence) and can be achieved with high economic growth (high confidence) {Figures
SPM4). (2.4.3, 2.5.1, 2.5.3, Figure 2.4, Figure 2.28, 5.4.1, 5.4.1, 5.4.2, Figure 5.4}
D4.3. Mitigation measures of 1.5°C-consistent pathways can create risks for development,
for example as a result of the economic losses from the projected decline in the use of coal,
oil and gas (high confidence). Policies that promote diversification of the economy and the
energy sector can facilitate this transition (high confidence). {5.4.1, Box 5.2}
D4.4 Redistributive policies 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-consistent pathways (high confidence). {2.4.3, 4.2.1, Box 4.8, 5.5.3, Box 5.3}
D5. Pursuing climate-resilient development pathways can limit warming to 1.5°C while
adapting to its consequences and simultaneously achieving sustainable development
(high confidence). {Box 1.1, 1.4, 2.5, 4.4, Box 4.6, 5.5.3, Box 5.3}
D5.1. Sustainable development can enable societal and systems transformations that can
help limit warming to 1.5°C (high confidence). Pathways that are consistent with sustainable
development are associated with reduced mitigation and adaptation challenges, and limit
warming to 1.5°C at comparatively lower mitigation costs as compared to development
pathways that have high inequality and poverty (high confidence). {2.5.3, 5.5.2}
D5.2. The integration between adaptation, mitigation, and sustainable development requires
a systematic approach to reconciling trade-offs and exploiting synergies across sectors and
spatial scales (very high confidence). The potential for climate-resilient development
pathways differs between and within regions and nations, due to different development
contexts and starting points (very high confidence). {4.4.1, 4.4.3, 4.5.4, 5.5.1, 5.5.3, Figure
5.1}
D5.3. 1.5°C-consistent pathways that encompass joint, iterative planning and transformative
visions and consider power asymmetries and unequal opportunities for development at
multiple levels show potential for sustainable futures and benefit for all affected populations
(high confidence). {5.5.3, Figure 5.6, 5.6.4, Box 5.3, Cross-Chapter Box 13 in Chapter 5}
D6. Policy implementation to successfully limit warming to 1.5°C and to adapt to
global warming of 1.5°C implies international cooperation and strengthening
institutional capacity of national and sub-national authorities from civil society, the
private sector, cities, local communities and Indigenous peoples (high confidence).
{4.4, 4.2}

 D6.1. Transformational adaptation implies deep and long-term societal changes linked to
poverty reduction and promoting equity with benefits for sustainable development goals.
These changes can be enabled by multi-level governance, coordinated sectoral and crosssectoral policies, collaborative stakeholder partnerships and innovative financing
mechanisms that provide greater access to financing and technology. (high confidence).
{4.2.2, 4.4.1, 4.4.3, 4.5.3, Cross-Chapter Box 9 in Chapter 4, 5.3.1}
D6.2. Implementing 1.5°C-consistent climate responses in developing countries and for poor
and vulnerable people requires international resources supporting access to finance,
technology and capacity building (high confidence). Financial, institutional and innovation
capabilities currently fall short of implementing far-reaching measures at scale in all
countries (high confidence). Enhanced capacities of local public and private sectors support
the deployment of context-specific climate responses and hence support systems’ transitions
to limit warming to 1.5°C (high confidence). {2.5.2, 4.2.2, 4.4.1, 4.4.2, 4.4.4, 4.4.5}
D6.3. International funding and technology transfer can support fast and profound local
transformation when they consider the context-specific needs of recipients (high confidence).
Strengthened global-to-local structures enable inclusive access to finance and technology
and ensure participation, transparency, capacity building, and learning among different
players (high confidence) {4.4.1, 4.4.4, 5.5.3, Cross-Chapter Box 13 in Chapter 5, 5.6.1,
5.6.3}
D6.4. International agreements that are sensitive to equity and the SDGs enable
transformation consistent with a 1.5°C warmer world. The governance of global partnerships
involving non-state actors including public and private sectors, civil society and scientific
institutions supporting sustainable development and poverty eradication would facilitative
actions and responses consistent with the constraining global warming to 1.5°C (very high
confidence). {1.4, 4.4, 4.4.1, 4.2.2, 4.4.3, 4.5.3, 5.3.1, 5.6.2, Box 5.3}

[1] FOOTNOTE: The assessment covers literature accepted for publication by May 15, 2018.
[2] FOOTNOTE: Each finding is grounded in an evaluation of underlying evidence and agreement. In many
cases, a synthesis of evidence and agreement supports an assignment of confidence. The summary terms for
evidence are: limited, medium or robust. For agreement, they are low, medium or high. A level of confidence is
expressed using five qualifiers: very low, low, medium, high and very high, and typeset in italics e.g. Medium
confidence. The following terms have been used to indicate the assessed likelihood of an outcome or a result:
virtually certain 99-100% probability, very likely 90-100%, likely 66-100%, about as likely as not 33-66%, unlikely
0-33%, very unlikely 0-10%, exceptionally unlikely 0-1%. Additional terms (extremely likely 95-100%, more likely
than not >50-100%, more unlikely than likely 0-<50%, extremely unlikely 0-5%) may also be used when
appropriate. Assessed likelihood is typeset in italics e.g. very likely. See for more details: Mastrandrea, M.D.,
C.B. Field, T.F. Stocker, O. Edenhofer, K.L. Ebi, D.J. Frame, H.Held, E.Kriegler, K.J. Mach, P.R. Matschoss, G.K.
Plattner, G.W. Yohe and F.W Zwiers, 2010: Guidance Note for Lead Authors of the IPCC Fifth Assessment Report
on Consistent Treatment of Uncertainties, Intergovernmental Panel on Climate Change (IPCC), Geneva,
Switzerland, 4pp
[3] FOOTNOTE: This range span several available peer-reviewed estimates of the observed global temperature
change and also represents a likely range in warming to the decade 2006-2015, accounting for additional
uncertainty due to possible short-term natural variability. {1.2.1, Table 1.1}
[4] FOOTNOTE: The change in the top-of-atmosphere balance between incoming and outgoing energy resulting
from a human or natural perturbation to the climate system, allowing the atmosphere and land-surface to adjust
but retaining sea-surface temperatures and sea-ice at their unperturbed state (called “Effective Radiative Forcing”
in previous reports).
[5] FOOTNOTE: Region definition based on IPCC regions (AR5, SREX; see Fig. 3.2)

 [6] FOOTNOTE: New literature consistently shows larger remaining 1.5°C and 2°C carbon budgets compared to
those reported in AR5. This literature does not challenge the AR5 relationship between cumulative emissions and
global-mean temperature but expresses the remaining carbon budget relative to a recent period that reflect the
observational record, rather than relative to the preindustrial period.
[7] FOOTNOTE: For consistency with other IPCC assessments, greenhouse gas emissions have been
aggregated to CO2-equivalent emissions with 100-year GWP values of the IPCC Second Assessment Report.
[8] FOOTNOTE: Four archetypes of 1.5°C-consistent pathways are shown, which illustrate different approaches
to reduce GHG emissions. The S5 pathways pursues GHG intensive lifestyles and focuses on technological
means to reduce GHG emissions through CDR. The S1 and LED pathways pursue sustainable development and
lifestyle with strong energy efficiency improvements and low energy demand, with the LED pathway avoiding the
use of carbon capture and storage altogether. The S2 pathways is a middle-of-the-road scenario which continues
historical patterns of societal and technological development with a mix of supply and demand-side measures.