2019 Was Second-Hottest Year On Record, Capping Off Hottest Decade

Last year was the second-hottest year ever recorded. And it capped off the hottest decade since at least 1880, when modern recordkeeping began.

NASA and NOAA announced the conclusions Wednesday. The organizations conducted separate but similar studies.

NOAA concluded that average temperatures in 2019 were 1.7 degrees Fahrenheit warmer than the average temperatures for the whole century. The only year hotter than last year was 2016.

NOAA also reports that ocean heat content — or the amount of heat stored in the upper-levels of the ocean — was the highest its ever been in 2019. High ocean heat can contribute to rising sea levels.

NASA found every decade since the 1960s "has been warmer than the one before." A NASA official said, "This shows that what’s happening is persistent, not a fluke due to some weather phenomenon."

NASA scientists have concluded the trend is mostly caused by humans; increased carbon dioxide and other greenhouse gases are the main culprit.