Warmest End to the Warmest Year on Record

Thomas Schueneman

Sea surface temperature - October 2015

The latest State of the Climate report from the National Oceanic and Atmospheric Administration (NOAA) continues with its broken record of broken records. The NOAA report states that not only was 2015 the warmest year on record, it broke the record by the widest margin ever.

Average global land and ocean surface temperature was 1.6° F (0.90° C) above the 20th century average, beating the 2014 record of 0.29° F (0.16° C). 2015 marks the fourth year this century that global temperatures have broken the 136-year record. 

Global land surface temperature in 2015 was 2.39° F (1.33° C) above the 20th century average, beating the record set in 2007 by 0.45° F (0.35° C), again the widest margin for annual average land surface temperature. 

For the oceans, the global surface temperature in 2015 was 1.33° F (0.74°) above the 20th century average, beating the record set last year. Scientists consider not only continuing broken temperature record, but the margin by which they were broken in 2015 as significant.

“A lot of times, you actually look at these numbers, when you break a record, you break it by a few hundredths of a degree,” Thomas Karl, director of NOAA’s National Centers for Environmental Information, said in the Washington Post. “But this record, we literally smashed. It was over a quarter of a degree Fahrenheit, and that’s a lot for the global temperature.”

Ocean-land surface temperatures 2015

December's record heat

For December, average global land and sea surface temperature was 2° F (1.11° C) above the 20th century average, the highest in the 1880-2015 record, beating the previous record warmth set in 2014 by 0.52° F (0.29° C). December 2015 was also the highest departure of all months in the historical record above the 20th century average, for the first time reaching 2° F above any previous month's average.

El Niño

Certainly some of the record-breaking heat in 2015 is attributable to the powerful El Niño that has driven enormous heat in the Pacific Ocean, but in contrast to the last big El Niño in 1998, 2015 was considerably hotter and the warmth spread across almost all regions of the globe, with one month after another breaking records. 1998, a banner year for climate "skeptics" claiming that's when global warming "stopped," now ranks "5th or 6th." Well below many subsequent record-breaking years. 

“It’s breaking the record because we also have this unusually strong El Niño, but at the same time we know the ocean is now absorbing two times more heat than around the last time we had a big El Niño, which is quite a while ago,” saidTexas Tech University climate scientist Katharine Hayhoe.

NASA concurs: 2015 warmest year on record

NASA and NOAA keep separate temperature datasets which don't always perfectly agree. Gavin Schmidt, NASA's director at the Goddard Institute for Space Studies, says the two datasets show "relatively little disagreement this year."

Schmidt also concurred that the El Niño does not alone account for the exceptional record-breaking warmth throughout 2015.

“The interesting thing is that 2015 did not start with an El Niño,” Schmidt said. “It was warm right from the beginning.”

Image credits: NOAA


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