US government scientists have said 2021 was the sixth-warmest year on record, and they are putting the blame squarely on climate change.
On average, 2021 was 1.51 degrees Fahrenheit (0.84 degrees Celsius) hotter than the baseline between 1901 and 2000, the National Oceanic and Atmospheric Administration (NOAA) said in a report issued on Thursday.
NASA, the North American Space Agency, came to similar conclusions in a report released in conjunction with data from NOAA. In its assessment, NASA said 2021 was tied for the sixth hottest year.
The last eight years were the eight hottest and the last decade was the warmest since record-keeping began in 1880, officials from the two agencies said.
Global warming is “very real. It’s now, and it’s impacting real people,” Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, told the Reuters news agency.
La Nina, a climate phenomenon centred in the eastern Pacific, slightly cooled global temperatures compared with what they would have been without it, scientists said.
Still, they said 2021 was the hottest La Nina year on record and that the year did not represent a cooling off of human-caused climate change but provided more of the same heat.
“So it’s not quite as headline-dominating 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.”
In the Arctic, often seen as a harbinger of broader environmental changes, maximum sea ice levels were their seventh-smallest on record, NOAA said.
Arctic sea-ice coverage has dropped by roughly 30 percent since 1980, NASA reported, and the polar region is heating about three times faster than the rest of the planet.
A key indicator of climate change, the heat content of the world’s oceans, reached a record level in 2021, the agencies said. Oceans absorb more than 90 percent of the excess heat trapped in the earth’s atmosphere by greenhouse gases, and those warmer waters influence weather patterns and changes in currents.
“What’s scientifically interesting about that is it tells us why the planet is warming,” Schmidt said. “It’s warming because of our impacts on greenhouse gas concentrations.”
For their 2022 outlook, scientists said they expect another year of rising heat.
“There is a 10 percent change 2022 will rank first (for heat),” Russ Vose, chief analyst for NOAA’s National Centers for Environmental Information told reporters on Thursday. “And a 99 percent chance it will rank in the top 10 hottest.”