Projected Climate Change,
Potential Impacts andAssociated Risks
Section B continued: Impacts Guiding AMBITION andCHOICES in Mitigation and Adaptation
Jason Florio / Aurora Photos

Impacts of global warming:
Where do we want to go?
At 1.5°C compared to 2°C:
• Less impacts from extreme weather wherepeople live
• By 2100, global mean sea level rise will bearound 10 cm lower …. but will continue torise for centuries• 10 million fewer people exposed to risk ofrising seas (…less coastal ecosystems
exposed)Jason Florio / Aurora Photos• Sea level slide Andres

1.5°C2°C

SR 1.5

Where do we want to go?
At 1.5°C compared to 2°C:
• Lower impact on biodiversity and species• Smaller reductions in yields of maize, rice,wheat crop yields• Global population exposed to water
shortages is up to 50% less (also less water
shortages for ecosystems)

Andre Seale / Aurora Photos

SPM 1.5°C: Terrestrial biodiversity• Of 105,000 species studied, 6% of insects, 8% of plants and
4% of vertebrates are projected to lose over half of theirclimatically determined geographic range for global warmingof 1.5°C, half of the respective numbers at 2°C.
• Approximately 4% (interquartile range 2–7%) of the global
land area is projected to undergo a transformation ofecosystems from one type to another at 1°C of global
warming, compared with 13% (interquartile range 8–20%) at
2°C. This indicates that the area at risk is projected to beapproximately 50% lower at 1.5°C compared to 2°C.

Terrestrial
biodiversity
P. Smith et al. 2018

Where do we want to go?

At 1.5°C compared to 2°C:
• Lower impacts on biodiversity and species

no impact
on biodiversity
at 1.5 vs. 2°C

beneficialfor biodiversity
at 1.5 vs. 2°C
Terrestrial Meta-analysis as in SR1.5

ILLUSTRATIVE EXAMPLE

Where do we want to go?
At 1.5°C compared to 2°C:
• Up to several hundred million fewer people
exposed to climate-related risk andsusceptible to poverty by 2050
• Lower risk to fisheries & the livelihoods that
depend on them

Natalie Behring / Aurora Photos

Where do we want to go?
At 1.5°C compared to 2°C:
• Disproportionately high risk for Arctic,
dryland regions, small island developing
states and least developed countries• Lower risks for health, livelihoods, foodsecurity, water supply, human security andeconomic growth• A wide range of adaptation options can reduceclimate risks; less adaptation needs at 1.5°C
Jason Florio / Aurora Photos

Where do we want to go?

At 1.5°C compared to 2°C:
• Reduced risk to human health – lower heatrelated morbidity and mortality

Placeholder
picturefromfre site

… on a rise linked tostrengthened increase inheat wave exposures…

(Lancet 2018)

ILLUSTRATIVE EXAMPLE, TO BE ASSESSED IN AR6

|2.0°C
1.5°C

Arctic Sea Ice
Coral Reefs

Global biodiversity

Confidence level : M, medium; H, high; VH; very high

IPCC SR1.5, 2018

|….half a degree matters… every bit of warming matters….
… for ecosystems, biodiversity and humankind

2.0°C
1.5°C

...less loss and damage at 1.5°C
Confidence level : M, medium; H, high; VH; very high
IPCC SR1.5, 2018OBSERVATIONS

0.8 to 1.0°C

Vulnerable ecosystem identified in AR5 and SR1.5Warm water coral reefs under various pressures
Assessing risk of global warming

Even in a 1.5°C warmer
world.... high risk of losing
70 to 90% of coral reefs
and their services tohumankind; … evenhigher losses at 2°C

2.0°C
1.5°C
20062015

low mod. high very highRisk level
Verons 20092016

Drivers of change: Warming and velocity....

+2°C AR5: Marine biodiversity
RCP 4.5
Garcia-Molinos
et al. 2015,2017 NCC

RCP4.5 versus 8.5
Ultimate Species Heat Limits surpassed in Tropics+4°C

RCP 8.5
Large changes in community composition expecteddriven by local invasions and losses

ILLUSTRATIVE EXAMPLE

Vulnerable ecosystems identified in AR5 and SR1.5:
Arctic summer sea ice systems

≥2°C

1.5°C

RCP 2.6

RCP 8.5

ambitious mitigation

business as usual

1 in 100 years
ice-freeat 1.5°C> 1 in 10years icefree at2°C©H.O. Pörtner

AR5 WGI SPM.7b, 8c

Ambitious emissions reductions
have...
• Co-benefits for• Human health• Reduced competition for land (BECCS)• Food security for humankind••Peter Essick / Aurora Photos

Ecosystem restoration and carbonstorage (soils and biomass)
Biodiversity conservation

For minimizing impacts and associated risks….

Half a degree…,…every bit of warming
matters
Each year matters
Each choice matters
Ashley Cooper/ Aurora Photos