It was also nominally the warmest year for Europe (and particularly the hottest in France, Germany and Switzerland) since continental records began in 1910.
The UN's World Meterological Organisation said in November that 2018 was set to be the fourth warmest year in recorded history, stressing the urgent need for action to rein in runaway planetary warming.
The U.S. government's National Oceanic and Atmospheric Administration said 2018's average temperature was 58.42 degrees (14.69 Celsius), which is 1.42 degrees (0.79 Celsius) warmer than the 20th century average. Climate change has accelerated the rate of ice loss across the continent.More news: Winter Storm Maya Arrives in the Pacific Northwest
The Earth experienced its fourth-hottest year in more than 136 years in 2018.
In order to avoid the worst effects of climate change, global temperatures cannot exceed more than two degrees Celsius.
The obvious long-term trend of steady warming makes it easier to more accurately predict near future warming, said NASA chief climate scientist Gavin Schmidt.
NASA's temperature analyses incorporate surface temperature measurements from 6,300 weather stations, ship- and buoy-based observations of sea surface temperatures, and temperature measurements from Antarctic research stations.More news: Warren: 'I Am a Candidate for President'
"The long-term temperature trend is far more important than the ranking of individual years, and that trend is an upward one", Petteri Taalas, secretary general of the World Meteorological Organization, told The Guardian.
An independent analysis released last month by Berkeley Earth calculated that in 2018, 85 percent of the Earth's surface was significantly warmer than the planet's average temperature from 1951 to 1980. That would be warmer than the last four years.
"I don't believe it", Trump said at the time without offering any evidence to counter the conclusions of hundreds of the nation's leading climate scientists. It warned that intense heatwaves "are becoming more frequent as a result of climate change". Instead, his administration is working to unravel Obama-era environmental rules in favor of policies that would allow more greenhouse gas emissions from cars, trucks and coal-fired power plants. Even an increase in 1.5 could be a great risk to the stability of the world.More news: ESA's new Mars rover named after woman who unlocked DNA's structure