Cryosphere Impacts of Overshoot

"In pathways with no or limited overshoot of 1.5°C,
CO2 emissions must decline 40-60% [median 50%] by 2030.
"

Why 1.5°C is better than 2°C

 
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Iceberg in the Ross Sea. Image: Heidi Sevestre

Sea Level Rise from Ice Sheets

"Marine ice sheet instability in Antarctica 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." 
IPCC, 2018: Summary for Policymakers

 
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Mont Blanc, France. Image: Heidi Sevestre

Glacier and Snow Loss

"Mid-latitude glaciers and snow in the Alps, southern Andes/Patagonia,

Iceland, Scandinavia, New Zealand and North American Rockies can survive at 1.5°,

but these glaciers will disappear almost entirely at 2°C, and snow cover decrease."

ICCI, 2019: Cryosphere1.5º: Where Urgency and Ambition Meet – Why Cryosphere Dynamics Must Mean 1.5° Pathways for 2020 NDCs

 
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A typical small Norwegian fishing vesle called a "sjark" on the Norwegian Arctic coast

Polar Ocean Acidification

"The level of ocean acidification due to increasing CO2 concentrations associated with global warming of 1.5°C is projected to amplify 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."
IPCC, 2018: Summary for Policymakers

 
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Sunrise over sea ice. Image: Rowan Romeyn / Alamy Stock Photo

Disappearance of Summer Arctic Sea Ice

"The probability of a sea ice-free Arctic Ocean during summer is substantially lower

at global warming of 1.5°C when compared to 2°C."
IPCC, 2018: Summary for Policymakers

 
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Erosion along the Arctic coast in Alaska’s Teshekpuk Lake Special Area.Image: Brandt Meixell/USGS.

Carbon Emissions from Permafrost

"High-latitude tundra and boreal forests are particularly at risk…

Limiting global warming to 1.5°C rather than 2°C is projected to prevent

the thawing over centuries of 1.5-2.5 million km2 of permafrost."
IPCC, 2018: Summary for Policymakers