https://www.sciencenews.org/article/2019-second-warmest-year-record-hottest-decade

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By Carolyn Gramling

JANUARY 15, 2020 AT 2:33 PM

The year 2019 is officially the second warmest in the 140-year record of modern temperatures compiled by both NASA and the U.S. National Oceanographic and Atmospheric Administration, scientists said January 15. The five warmest years on record have all occurred since 2014 — making 2019 the end to the hottest decade ever recorded.

The more important takeaway from the data is not how each of the last five years is ranked, but “the consistency of the long-term trends that we’re seeing,” climate scientist Gavin Schmidt said during a news conference.

“The top five years are the last five years, [and] the last decade is the warmest,” said Schmidt, who is the director of NASA’s Goddard Institute for Space Studies in New York City. Furthermore, since the mid-20th century, “every decade has been warmer than the last, and not by a small amount.”

From January to December 2019, the mean global temperature was 0.95 degree Celsius higher than the long-term average from 1901 to 2000, and about 0.98 degrees warmer than the average global temperature from 1951 to 1980.

Global hot spots

The average global temperature in 2019 was 0.98 degrees Celsius higher than the mid-century average from 1951–1980, making the year the second warmest in 140 years of modern record keeping.

2019 global temperatures compared with 1951–1980 averages

NOAA, NASA

During the hottest recorded year, 2016, global average temperatures were 0.99 degrees above the mid-century mean. But temperatures that year were influenced by a strong El Niño Southern Oscillation weather pattern (SN: 8/21/19), which historically increases the average global temperature, the researchers noted in the news conference, held during the American Meteorological Society’s annual meeting in Boston. El Niño had an impact on 2019 temperatures too, but it was much smaller than in 2016, Schmidt said. If El Niño wasn’t a factor, 2017 would have been the hottest year on record, with 2019 coming in third.

The heat last year broke records in cities around the world (SN: 12/16/19) and helped fuel wildfires from the Arctic to Australia (SN: 8/2/19; SN: 1/9/20). The extent of sea ice in the Arctic was the third-lowest in records going back to 1979 in September 2019, after 2012 and 2007.

Baked Alaska

In the United States, average temperatures across the lower 48 states were cool relative to the past five years, just slightly above the long-term average for the 20th century. But Alaska saw its warmest year on record, with an average annual temperature of about 0.11° Celsius (32.2° Fahrenheit), about 3.4 degrees Celsius higher than the average temperature from 1925 to 2000. The southeast also sweltered under record-high temperatures.

Ranking of 2019 U.S. temperatures relative to the years from 1859 to 2019

NATIONAL CENTERS FOR ENVIRONMENTAL INFORMATION/NOAA