Past Abrupt Climate Warming Shows Cascading Impacts in Just Decades, but Persisting for Centuries

Nature Geoscience, July 29

This review paper assesses abrupt changes in climate over the past 30,000 years, and finds that interactions between the cryosphere and oceans produced some of the most dramatic events in this period, with persisting global consequences. Changes in the Atlantic Meridional Overturning Circulation (AMOC), one of Earth’s largest ocean circulation systems, appear strongly related to the collapse of one or both ice sheets; ice shelf breakup; retreat of polar glaciers; and deep ocean warming due to the massive amount of freshwater entering the ocean system due to this extensive ice loss. All of these dynamics resulted from much more gradual climate forcing (from slight orbital changes) than has occurred over the past century from human burning of fossil fuels and CO2 emissions. A series of especially abrupt events, detected in Greenland raised temperature by over 15°C in that region over just 30-70 years, and Europe warmed several degrees in that same time period; with consequences lasting several centuries. Authors emphasize the importance of calibrating Earth system models using such geological records, as we cannot hope to predict future potentially catastrophic changes for human society if our models do not capture past abrupt events.

https://www.nature.com/articles/s41561-021-00790-5