Two U.S. science agencies say 2021 was the sixth hottest year on record globally, making the year part of a long-term warming trend.

NASA and the National Oceanic and Atmospheric Administration on Thursday released measurements showing how hot last year was. It wasn't record hot, but the year's 58.5 degree average is not much behind the record.

These last eight years have been the eight hottest years on record. Last year, 1.8 billion people in 25 Asian, African and Middle Eastern nations had their hottest years on record. Scientists say heat-trapping gases from the burning of fossil fuels have warmed Earth about 2 degrees since the late 1800s.

NASA says in 2021 Earth was around 1.9 degrees Fahrenheit warmer than the 19th century average at the start of the industrial revolution.

Around the globe, scientists have ships, weather stations and ocean buoys recording Earth's temperature year-round. Scientists say many factors will affect the Earth's average temperature in any given year including La Niña, the phenomenon which is the colder atmospheric counterpart to El Niño's climate patterns in the tropical Pacific, NASA says.