Irreversible changes in surface temperature and precipitation to CO2 forcing

Anthropogenic global warming by carbon dioxide emissions may cause irreversible changes in a wide range of climate variables. A comprehensive understanding of this hysteresis effect and its regional patterns is, however, lacking. Here, we use the Community Earth System Model version 1.2 with a CO₂ removal scenario to show that surface temperature and precipitation exhibit globally widespread irreversible changes. To explore the climate hysteresis and reversibility on a regional scale, we develop a novel method that quantifies their spatial patterns. Our experiments project that 89% and 58% of the global area experiences irreversible changes in surface temperature and precipitation, respectively. Strong irreversible response of surface temperature is found in the Arctic, Southern Ocean, and North Atlantic Ocean and of precipitation in the global monsoon regions, tropical Pacific, and the Himalayas. The identified global land hotspots of irreversible changes can indicate elevated risks of negative impacts on developing countries.