The world in 2017 saw some of the highest average surface temperatures ever recorded, surprising scientists who had expected sharper retreat from recent record years.
Scientists at NASA on Thursday ranked last year as the second-warmest year since reliable record-keeping began in 1880, trailing only 2016. The National Oceanic and Atmospheric Administration, which uses a different analytical method, ranked it third, behind 2016 and 2015.
What made the numbers unexpected was that last year had no El Niño, a shift in tropical Pacific weather patterns that is usually linked to record-setting heat and that contributed to record highs the previous two years. In fact, last year should have benefited from a weak version of the opposite phenomenon, La Niña, which is generally associated with lower atmospheric temperatures.
“This is the new normal,” said Gavin A. Schmidt, director of the Goddard Institute for Space Studies, the NASA group that conducted the analysis. But, he said, “It’s also changing. It’s not that we’ve gotten to a new plateau — this isn’t where we’ll stay. In ten years we’re going to say ‘oh look, another record decade of warming temperatures.’”