drivers during the overshoot period. WGI AR6 assessed that temporary overshoot of a 2ºC warming threshold has irreversible effects on global mean sea level and also effects on ocean heat content that persist beyond 2100 . Model results indicate that sea surface temperatures , Arctic sea ice , surface ocean acidification  and surface ocean deoxygenation  are reversible within years to decades if net emissions reach zero or below . Although changes in these surface ocean variables are reversible, habitat-forming ecosystems, including coral reefs and kelp forests, may undergo irreversible phase shifts with >1.5°℃ warming , and are thus at high risk this century in 1.5°C or 2ºC scenarios involving overshoot . In an overshoot scenario in which CO2 returns to 2040 levels by 2100 , SST and Arctic sea ice do not fully return by 2100 to levels prior to the CO2 peak  , suggesting that reversal of marine ecological impacts from 21st century climate impacts would extend into the 22nd century or beyond . Models also indicate that global sea level rise, as well as warming, ocean acidification and deoxygenation at depth, are irreversible for centuries or longer  .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report