Last year was the second-warmest across the globe since 1880, NASA reported Thursday.
The global surface temperature average in 2017 was 0.90 C warmer than the 1951–1980 mean, surpassed only by 2016.
According to the National Oceanic and Atmospheric Administration (NOAA), however, 2017 was the third-warmest year. Its analysis concluded that the average global land and ocean surface temperature was 0.84 C above the 20th century average. Globally, the temperature averaged 14.7 C.
Also on Thursday, the United Nation’s World Meteorological Organization released its data, which concluded 2017 was 1.1 C above the pre-industrial era at 14.3 C.
“Seventeen of the 18 warmest years on record have all been during this century, and the degree of warming during the past three years has been exceptional,” WMO Secretary-General Petteri Taalas said in a statement.
“Arctic warmth has been especially pronounced, and this will have profound and long-lasting repercussions on sea levels, and on weather patterns in other parts of the world.”
The differences appear to be due to the different methods used to collect data. However, both NOAA and NASA note that the five warmest years have all occurred since 2010.
“We’re in a long-term warming trend,” Gavin Schmidt of NASA’s Goddard Institute for Space Studies said at a news conference on Thursday. “The planet is warming remarkably uniformly.”
“There is year-to-year variability, but the long-term trends are clear,” Deke Arndt, chief of the global monitoring branch of NOAA’s National Centers for Environmental Information, said.
And the Arctic is feeling the heat. Arndt noted that the region is warming “much faster than the global average.”
Over the past century, Earth’s global temperature has risen by more than 1 C, largely due to an increase of carbon dioxide and other human-made emissions, NASA said in its report.
“Basically all of the warming in the last 60 years is attributable to human activities, and carbon emissions is the No. 1 component of that,” Schmidt said.
While El Nino and La Nina can play a role in global temperatures, they contribute to short-term changes in global temperatures, as was evident in both 2015 and 2016. El Nino causes a rise in global temperatures, while La Nina tends to cause some cooling.
There was no El Nino in 2017, but La Nina began at the end of the year. NASA noted that an analysis which removed both patterns concluded that 2017 would have been the warmest year on record.
“It’s the long-term trend that’s pushing these numbers up,” Schmidt said.