Last year was the fourth-warmest worldwide since 1880, said NASA and the National Oceanic and Atmospheric Administration on Wednesday, ranking behind 2016, 2017 and 2015. “[Two-thousand eighteen] is yet again an extremely warm year on top of a long-term global warming trend,” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies.
Global temperatures in 2018 were 1.5 degrees F (0.83 degrees C) warmer than the 1951-80 average, said the NASA institute. The past five years are the warmest on record, it said.
Since the 1880s, the average global surface temperature has rise about 2 degrees F (1 degree C), driven in large part by greenhouse gases released by human activities, said Schmidt. Agriculture is a major contributor to global warming, accounting for a quarter of manmade greenhouse-gas emissions. Factor in the reduction of natural habitat caused by agriculture — forests, savannas, and tropical rainforest lost — and the figure amounts to as much as a third of all emissions.
Not every region on earth experienced the same amount of warming. The annual mean temperature in the continental United States was the 14th warmest. Warming trends were strongest in the Arctic, with continued loss of sea ice.
“The impacts of long-term global warning are already being felt — in coastal flooding, heatwaves, intense precipitation and ecosystem change,” said Schmidt in a NASA release. In making its temperature analyses, NASA uses data from 6,300 weather stations, ship and buoy-based measurements of sea temperatures and temperature recording by Antarctic research stations.