Editing IPCC:AR6/WGI/Chapter-9 (section)

=== Cryospheric Changes and Sea Level Rise at Specific Levels of Global Warming ===

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'''At sustained warming levels between 1.5°C and 2°C''' , the Arctic Ocean will become practically sea ice-free in September in some years ( ''medium confidence'' ); the ice sheets will continue to lose mass ( ''high confidence'' ), but will not fully disintegrate on time scales of multiple centuries ( ''medium confidence'' ); there is ''limited evidence'' that the Greenland and West Antarctic ice sheets will be lost almost completely and irreversibly over multiple millennia; about 50 to 60% of current glacier mass excluding the two ice sheets and the glaciers peripheral to the Antarctic Ice Sheet will remain, predominantly in the polar regions ( ''low confidence'' ); Northern Hemisphere spring snow cover extent will decrease by up to 20% relative to 1995–2014 ( ''medium confidence'' ); the permafrost volume in the top 3 m will decrease by up to 50% relative to 1995–2014 ( ''medium confidence'' ). Committed GMSL rise over 2000 years will be about 2 to 6 m with 2°C of peak warming ( ''medium agreement, limited evidence'' ). {9.3.1, 9.4.1, 9.4.2, 9.5.1, 9.5.2, 9.5.3, 9.6.3}

'''At sustained warming levels between 2°C and 3°C''' , The Arctic Ocean will be practically sea ice free throughout September in most years ( ''medium confidence'' ); there is ''limited evidence'' that the Greenland and West Antarctic ice sheets will be lost almost completely and irreversibly over multiple millennia; both the probability of their complete loss and the rate of mass loss will increase with higher temperatures ( ''high confidence'' ); about 50 to 60% of current glacier mass outside Antarctica will be lost ( ''low confidence'' ); Northern Hemisphere spring snow cover extent will decrease by up to 30% relative to 1995–2014 ( ''medium confidence'' ); permafrost volume in the top 3 m will decrease by up to 75% relative to 1995–2014 ( ''medium confidence'' ). Committed GMSL rise over 2000 years will be about 4 to 10 m with 3°C of peak warming ( ''medium agreement, limited evidence'' ). {9.3.1, 9.4.1, 9.4.2, 9.5.1, 9.5.2, 9.5.3, 9.6.3}

'''At sustained warming levels between 3°C and 5°C''' , the Arctic Ocean will become practically sea ice free throughout several months in most years ( ''high confidence'' ); near-complete loss of the Greenland Ice Sheet and complete loss of the West Antarctic Ice Sheet will occur irreversibly over multiple millennia ( ''medium confidence'' ); substantial parts or all of Wilkes Subglacial Basin in East Antarctica will be lost over multiple millennia ( ''low confidence'' ); 60 to 75% of current glacier mass outside Antarctica will disappear ( ''low confidence'' ); nearly all glacier mass in low latitudes, Central Europe, Caucasus, western Canada and the USA, North Asia, Scandinavia and New Zealand will ''likely'' disappear; Northern Hemisphere spring snow cover extent will decrease by up to 50% relative to 1995–2014 ( ''medium confidence'' ); permafrost volume in the top 3 m will decrease by up to 90% compared to 1995–2014 ( ''medium confidence'' ). Committed GMSL rise over 2000 years will be about 12 to 16 m with 4°C of peak warming and 19 to 22 m with 5°C of peak warming ( ''medium agreement, limited evidence'' ). {9.3.1, 9.4.1, 9.4.2, 9.5.1, 9.5.2, 9.5.3, 9.6.3}

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