Global Warming of 1.5°C

Global Warming of 1.5°C
An IPCC special report on the impacts 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 thethreat of climate change, sustainable
development, and efforts to eradicate
poverty.

The report in numbers

91 Authors from 40 Countries
133 Contributing authors
6000 Studies

1 113 Reviewers

42 001 Comments

Climate change is already affecting people,
ecosystems and livelihoods around the world
Limiting global warming to 1.5°C is notimpossible – but it would require
unprecedented transitions in all aspects ofsociety
There are clear benefits to keeping warming
to 1.5°C rather than 2°C or higher
Limiting warming to 1.5°C can go hand inhand with achieving other world goals

Global warming of 1.5°C (SR1.5)
Chapter 1 - Framing and context (integration WGI-WGII-III)
Chapter 2 - Mitigation pathways compatible with 1.5°C in the context
of sustainable development (integration WGI-WGIII, pathways)
Chapter 3 - Impacts of 1.5°C global warming on natural and humansystems (integration WGI-WGII, global – regional)
Chapter 4 - Strengthening and implementing the global response to
the threat of climate change (systems transitions, behaviour,dimensions of feasibility)
Chapter 5 - Sustainable development, poverty eradication andreducing inequalities (ethics, equity, societal transformation, SDGs)

Understanding Global
Warming of 1.5°C

Where are we?
Since pre-industrial times, human activities havecaused approximately 1.0°C of global warming.
• Already seeing consequences for people,nature and livelihoods• At current rate, would reach 1.5°C between
2030 and 2052

• Past emissions alone do not commit theworld to 1.5°C
Ashley Cooper / Aurora Photos

SPM1|

Cumulative emissions of CO2 and future non-CO2 radiative
forcing determine the probability of limiting warming to 1.5°C

SPM1|

Cumulative emissions of CO2 and future non-CO2 radiative
forcing determine the probability of limiting warming to 1.5°C

SPM1|

Cumulative emissions of CO2 and future non-CO2 radiative
forcing determine the probability of limiting warming to 1.5°C

SPM1|

Cumulative emissions of CO2 and future non-CO2 radiative
forcing determine the probability of limiting warming to 1.5°C

SPM1|

Cumulative emissions of CO2 and future non-CO2 radiative
forcing determine the probability of limiting warming to 1.5°C

SPM1|

Cumulative emissions of CO2 and future non-CO2 radiative
forcing determine the probability of limiting warming to 1.5°C

SPM1|

Cumulative emissions of CO2 and future non-CO2 radiative
forcing determine the probability of limiting warming to 1.5°C

Faster immediate CO2 emission
reductions limit cumulative CO2emissions

SPM1|

Cumulative emissions of CO2 and future non-CO2 radiative
forcing determine the probability of limiting warming to 1.5°C

SPM1|

Cumulative emissions of CO2 and future non-CO2 radiative
forcing determine the probability of limiting warming to 1.5°C
Maximum temperature rise is determined by cumulative net CO2
emissions and net non-CO2 radiative forcing due to methane, nitrous
oxide, aerosols and other anthropogenic forcing agents.

Projected Climate
Change, Potential Impacts
and Associated Risks

Spatial patterns of changes in mean temperature
Global warming of 1.5°C26 CMIP5 models; hatching : 66% model agreement

2°C

Spatial patterns of changes in mean temperature and precipitation
Global warming of 1.5°C

26 CMIP5 models; hatching : 66% model agreement

2°C

Spatial patterns of changes in mean temperature and precipitation
Global warming of 1.5°C
Global warming of 1.5°C

26 CMIP5 models; hatching : 66% model agreement

2°C
2°C

DifferencesDifferenceSpatial patterns of changes in extreme temperature
Global warming of 1.5°C
Number of hot days(days)

Temperature ofhottest days (°C)

Temperature ofcoldest nights (°C)

2°C

Spatial patterns of changes in extreme temperature and precipitation
Global warming of 1.5°C

Number of hot days(days)

Temperature ofhottest days (°C)

Temperature ofcoldest nights (°C)

Extremeprecipitation (%)

2°C

Spatial patterns of changes in extreme temperature and precipitation
Global warming of 1.5°C

Number of hot days(days)

Temperature ofhottest days (°C)

Temperature ofcoldest nights (°C)

Extremeprecipitation (%)

2°C

DifferenceEmergence and intensity of regional climate change hot spotsArctic summer sea-ice
 L maintained; 50% or higher risk to be ice free; VL to be ice free Habitat (polar bear, whales, seals, sea birds) : losses; losses; critical losses Arctic fisheries : benefits; benefits; benefits

Warming of 1.5°C or lessWarming of 1.5ºC-2°C
Warming > 2°C

L, likely
VL, very likely
LC, low confidenceMC, medium confidenceHC, high confidenceEmergence and intensity of regional climate change hot spots
Arctic land regions
 Cold extreme: warm up to 4.5°C (HC); warm up to 8°C (HC); VL drastic warming Tundra : L biome shifts; L more shifts; drastic biome shift possible (LC) Permafrost : L 17-44% reduction; L larger (28-53%); potential for collapse (LC) Boreal forest : increased mortality at S. boundary (MC); further (MC); potential dieback (LC)

Warming of 1.5°C or lessWarming of 1.5ºC-2°C
Warming > 2°C

L, likely
VL, very likely
LC, low confidenceMC, medium confidenceHC, high confidenceEmergence and intensity of regional climate change hot spots

Alpine regions
 Biomes : L severe shift; L even more severe; L critical

Warming of 1.5°C or lessWarming of 1.5ºC-2°C
Warming > 2°C

L, likely
VL, very likely
LC, low confidenceMC, medium confidenceHC, high confidenceEmergence and intensity of regional climate change hot spots

Mediterranean Extreme drought: increase probability(MC); robust increase(MC); robust and large increase(MC) Runoff decrease: about 9% (MC); about 17% (MC); substantial reductions (MC) Water deficit: risk (MC); higher risks (MC); very high risks (MC)Warming of 1.5°C or lessWarming of 1.5ºC-2°C
Warming > 2°C

L, likely
VL, very likely
LC, low confidenceMC, medium confidenceHC, high confidenceEmergence and intensity of regional climate change hot spots

Tropics
 # hot days and nights, heatwaves: increases (HC); largest increase; oppressive, VL health impact
 Livestock heat stress : increased; onset of persistent (MC); L persistent Crop yields: risks; extensive risks (W. Africa, SE Asia, S. America); VL substantial reductions
 Rainforests : reduced biomass; larger reductions; reduced extent, potential forest dieback (MC)Warming of 1.5°C or lessWarming of 1.5ºC-2°C
Warming > 2°C

L, likely
VL, very likely
LC, low confidenceMC, medium confidenceHC, high confidenceEmergence and intensity of regional climate change hot spots
Warming of 1.5°C or lessWarming of 1.5ºC-2°C
Warming > 2°C

L, likely
VL, very likely
LC, low confidenceMC, medium confidenceHC, high confidence

Southeast Asia  flooding related to sea-level rise: risks; higher risks (MC); substantial increases in risk
 Asian monsoon : LC; LC; L increase in precipitation intensity
 Heavy precipitation: increase; stronger increase (MC); substantial increase Crop yield reductions: -; one third decline in per capita (MC); substantial reduction

Emergence and intensity of regional climate change hot spots
L, likely
VL, very likely
LC, low confidenceMC, medium confidenceHC, high confidence

Warming of 1.5°C or lessWarming of 1.5ºC-2°C
Warming > 2°C

West African and the Sahel Monsoon : uncertain ; uncertain ; strengthening (LC) Hot nights, longer, more frequent heat waves: L ; L further ; VL substantial   in maize and sorghum production: L, about 40%  suitable area; L larger ;major regional food insecurities (MC) Undernutrition risks : increased; higher; highEmergence and intensity of regional climate change hot spots
L, likely
VL, very likely
LC, low confidenceMC, medium confidenceHC, high confidence

Warming of 1.5°C or lessWarming of 1.5ºC-2°C
Warming > 2°C

Southern Africa
 Water availability: reductions (MC); larger reductions (MC); large reductions (MC)
 # of hot nights and  heat waves : increases (HC); further increase (HC); drastic increase (HC) Increased mortality from heat-waves: high risks; higher risks (HC);substantial impact on health and mortality (HC) Undernutrition / dryland agriculture and livestock: high risk; higher risk (HC); very high risks

Emergence and intensity of regional climate change hot spots
Warming of 1.5°C or lessWarming of 1.5ºC-2°C
Warming > 2°C

L, likely
VL, very likely
LC, low confidenceMC, medium confidenceHC, high confidence

Small islands: Inundation risk : land exposed; tens of thousands displaced ; substantial, widespread impacts
 Coastal flooding: risks; high risks ; substantial and widespread impacts
 Fresh water stress : increased; projected aridity; substantial and widespread impacts
 # of warm days : increase; further increase (70 warm days/year), persistent heat stress incattle ; persistent heat stress Loss of coral reefs: 70-90%; most coral reefs ; loss of most coral reefs (VL)