Thursday’s US findings roughly concur with numbers from the Japanese space agency JAXA and Britain’s weather service, the Met Office. Both agencies released data earlier Thursday that ranked 2017 third.
Japan’s analysis put 2017 at 0.39°C (0.7°F) over a 1981-2010 average, compared to the 0.45°C recorded in 2016. The Met Office put 2017 at a hair under 1°C (1.8°F) over an 1850-1900 baseline and 0.38 C over the 1981-2010 period.
But while different agencies have reached slightly different numbers, the long-term trends “are all very clear and independent of who is doing these analyses,” Schmidt said.
That increase is driven by human emissions of planet-warming carbon dioxide and other gases, which continue to build up in the atmosphere despite worldwide efforts to reduce them. Though a few cool spots appeared, mostly in the Pacific and North Atlantic oceans, “The planet is warming remarkably uniformly,” Schmidt added.
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The past few years have seen some dramatic manifestations of that trend, with sea ice at the poles retreating sharply from past high marks and a notable number of extreme weather events. Earlier this month, NOAA reported that 2017 was the third-warmest year on record in the continental United States, and the country saw 16 weather or climate-related disasters that inflicted $1 billion or more in damages — including hurricanes Harvey, Maria, and Irma, a deep drought in the upper Great Plains states, and massive wildfires in California and the mountain West.
The successive records set in 2015 and 2016 were driven in part by a strong El Niño, a cyclical pattern that occurs when the eastern and central Pacific Ocean warm up. The 2015-2016 El Niño brought warmer, wetter weather to the Northern Hemisphere but fueled intense drought and heat waves across Africa, Southeast Asia, and Australia.
The 2017 figure also tops 2014, another non-El Niño year that was the first of three straight annual records. Nine of the top 10 warmest years on record have occurred since 2000, with the El Niño year of 1998 coming in at No. 9. And last year was the 41st in a row to be warmer than the 20th century average.