We see far greater risk of massive irreversible sea level rise (SLR) at 2°C, on a scale of 12–20 meters or more in the long term. The climate record of the Earth over the pat few million years is quite clear:
Sea Level Rise from Ice Sheets
We see far greater risk of massive irreversible sea level rise (SLR) at 2°C, on a scale of 12–20 meters or more in the long term. The climate record of the Earth over the pat few million years is quite clear:
Sea Level Rise from Ice Sheets
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
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
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."
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
Antarctic sea ice in the Ross Sea. Image: Heïdi Sevestre
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
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