2021 Ranks as Fifth Hottest Year, With More Data Coming Soon


The year 2021 ended as the fifth hottest in records maintained by the European Union’s Copernicus Climate Change Service that go back to 1979. That finding comes from publicly available data analyzed by Zeke Hausfather, a climate scientist who posted his calculations on Twitter.

This is among the first readings of last year’s temperature data but it won’t be the last. Copernicus is expected to release its full results later this month. Additional global temperature data will be released from NASA, NOAA, the U.K. Met Office, and Berkeley Earth, which draw on records dating back to the 19th century. Officials from Copernicus did not respond to requests for comment on data posted to the agency’s website.

Hausfather, a research scientist at Berkley Earth, said in an email it’s likely that other data sources will rank 2021 somewhere between the fifth- and seventh-hottest years on record.

Last year did set the highest-ever June-to-August average land temperature. But a La Niña event, which is an occasional cooling pattern in the Pacific Ocean, arrived in October and caused temperatures to dip. That pattern makes winter milder in the southern U.S. and has been blamed for contributing to flooding in Indonesia and Australia.

It was enough to push 2021’s average temperature down closer to 2018 and 2015, according to Hausfather’s analysis of the Copernicus data. The last seven years are the hottest on record and 21 of the 22 hottest years have come since the year 2000, according to the Copernicus data.