Heating appears to accelerate as Earth hits 6th warmest year
Earth simmered to the sixth hottest year on record in 2021, according to several newly released temperature measurements.
And scientists say the exceptionally hot year is part of a long-term warming trend that shows hints of accelerating.
Two U.S. science agencies — NASA and the National Oceanic and Atmospheric Administration — and a private measuring group released their calculations for last year’s global temperature on Thursday, and all said it wasn’t far behind ultra-hot 2016 and 2020.
Six calculations found that 2021 was between the fifth and seventh hottest year since the late 1800s. NASA said 2021 tied with 2018 for sixth warmest, while NOAA puts last year in sixth place by itself.
Scientists say a La Niña — natural cooling of parts of the central Pacific that changes weather patterns globally and brings chilly deep ocean water to the surface — dampened global temperatures just as its flip side, El Niño, boosted them in 2016.
Still, they said 2021 was the hottest La Niña year on record and that the year did not represent a cooling off of humancaused climate change but provided more of the same heat.
“So it’s not quite as headlinedominating as being the warmest on record, but give it another few years and we’ll see another one of those” records, said climate scientist Zeke Hausfather of the Berkeley Earth monitoring group that also ranked 2021 the sixth hottest. “It’s the long-term trend, and it’s an indomitable march upward.”
The past eight years have been the eight hottest on record, NASA and NOAA data agree. Global temperatures, averaged over a 10-year period to take out natural variability, are nearly 2 degrees warmer than 140 years ago, their data shows.
The other 2021 measurements came from the Japanese Meteorological Agency and satellite measurements by Copernicus Climate Change Service in Europe and the University of Alabama in Huntsville.
The global average temperature last year was 58.5 degrees according to NOAA. In 1988, NASA’s then-chief climate scientist James Hansen grabbed headlines when he testified to Congress about global warming in a year that was the hottest on record at the time. Now, the 57.7 degrees of 1988 ranks as the 28th hottest year on record.
The deep ocean, where most heat is stored in the seas, also set a record for warmth in 2021, according to a separate new study.
“Ocean warming, aside from causing coral bleaching and threatening sea life and fish populations ... is destabilizing Antarctic ice shelves and threatens massive ... sea level rise if we don’t act,” said study co-author Michael Mann, a Pennsylvania State University climate scientist.