It was signposted all year, but North American agencies have confirmed: 2015 was the hottest year since records began in 1880.
NASA and the National Oceanic and Atmospheric Administration (NOAA) analysis showed that global surface air temperatures continued a long trend upward: 15 of the 16 warmest years on record have occurred since 2001.
Globally-averaged temperatures in 2015 surpassed the previous record set in 2014 by 0.13 Celsius. In a statement, NASA and NOAA said the only time the previous record had been beaten by such a margin was 1998.
2014 was the first year global average temperature were 1 degree Celsius or more above the 1880-1899 baseline.
NASA Administrator Charles Bolden said climate change was the “challenge of our generation”.
“Today’s announcement not only underscores how critical NASA’s Earth observation program is, it is a key data point that should make policy makers stand up and take notice – now is the time to act on climate.”
Earth’s average surface temperature has risen about 1 degree Celsius since the late-19th Century, largely driven by increased carbon dioxide and other human-made emissions into the atmosphere.
The long-term change has been visualised by GSFC Scientific Visualization Studio in a video showing a rolling five-year average temperature (orange colors represent temperatures that are warmer than the 1951-80 baseline average, and blues represent temperatures cooler than the baseline).
A warming El Niño was in effect for much of 2015, which Goddard Institute for Space Studies Director Gavin Schmidt said gave the temperatures “an assist”. “But it is the cumulative effect of the long-term trend that has resulted in the record warming that we are seeing.”
New Zealand’s National Institute of Water and Atmospheric Research (Niwa) found 2015 was not a particularly warm year for the country – the 27th warmest since records began – with El Niño dampening things down.
Featured image: Scientific Visualization Studio/Goddard Space Flight Center.