The 2010s were the hottest decade ever measured on Earth, and 2019 was the second-hottest year ever measured, scientists at NASA and the National Oceanic and Atmospheric Administration announced today.
After a year of flash droughts, rampant wildfires, and searing heat waves that set all-time records across Europe and turned parts of Greenland’s ice sheet into slush, the finding was not a surprise to researchers, or likely anyone else. But it capped an anxious decade that saw human-caused climate change transform from a far-off threat into an everyday fact of life.
Last year was 1.8 degrees Fahrenheit—or just under 1 degree Celsius—warmer than the 20th-century average, Gavin Schmidt, the chief climate scientist at NASA, said at a briefing announcing the news. Almost everywhere on the planet’s surface was warmer than average, though the Arctic was especially searing. “Every decade since the 1960s has been warmer than the decade previous,” he said.
In short, it’s bad, but you probably knew that already. At least four different groups of scientists, each working independently, have now concluded that the 2010s were the hottest decade of the modern era. (NASA and NOAA start this era at 1880, when they say weather record-keeping became reliable and widespread enough to trust, but the nonprofit research agency Berkeley Earth argues that 2019 was the second-warmest year since at least 1850.) What’s worse is that greenhouse-gas pollution from fossil fuels, which are the biggest driver of climate change, also surged to an all-time high last year, according to a preliminary estimate. Deke Arndt, a chief climate scientist at NOAA, said at the briefing that “an obvious signal” of this greenhouse-gas-powered heating had appeared in the upper layers of the ocean, which broke the all-time heat record last year.