Emerging threatsExtraordinary global heat continues

Published 19 September 2016

Although the seasonal temperature cycle typically peaks in July, August 2016 wound up tied with July 2016 for the warmest month ever recorded. August 2016’s temperature was 0.16 degrees Celsius warmer than the previous warmest August (2014). The month also was 0.98 degrees Celsius warmer than the mean August temperature from 1951-1980, according to NASA. The increasing warming is driven by carbon dioxide concentrations – which have passed the symbolic milestone of 400 parts per million in the atmosphere so far this year. Levels vary according to the season, but the underlying trend is upward. According to NOAA, the global monthly mean CO2 in July 2016 was 401.72 parts per million, up from 393.13 parts per million in July 2015.

The exceptionally long spell of record global heat, a surge in greenhouse gas concentrations, shocking coral reef bleaching, and long-term Arctic sea ice melt all add urgency to the need for world leaders to ratify and implement the Paris Agreement on climate change, according to the World Meteorological Organization (WMO).

United Nations Secretary-General Ban Ki-moon has convened a special high-level event on 21 September to speed up ratification or accession to the Paris Agreement, reached in December 2015.

“We have witnessed a prolonged period of extraordinary heat, which is set to become the new norm,” said WMO Secretary-General Petteri Taalas. “We have observed both unusually high concentrations of carbon dioxide and the record breaking temperatures. The high temperatures of the sea water has aggravated severe coral reef bleaching.”

“All these findings increase the urgency of action in the implementation of the Paris Agreement to avoid temperatures exceeding the 1.5-2.0°C range above the pre-industrial era,” said aalas.

August was the hottest August on record for both land and oceans, according to data from NASA’s Goddard Institute for Space Studies and the European Centre for Medium Range Weather Forecasting. NASA said that August 2016 tied with July 2016 as the hottest month ever recorded. The year to date has smashed all existing temperature records.

“The heat in high latitudes has been especially punishing for Arctic sea ice and the Greenland ice sheet”, said Taalas.

Arctic Sea Ice
The U.S. National Snow and Ice Data Center (NSIDC) said Thursday that the Arctic’s ice cover appears to have reached its minimum extent on 10 September 2016, at 4.14 million square kilometers (1.60 million square miles). It was statistically tied at second lowest in the satellite record with the 2007 minimum. The figures are provisional.

The WMO notes that the record lowest extent in the 37-year satellite record occurred on 17 September 2012, when sea ice extent fell to 3.39 million square kilometers (1.31 million square miles).

It was a stormy, cloudy, and fairly cool summer. Historically, such weather conditions slow down the summer ice loss.

“It really suggests that in the next few years, with more typical warmer conditions, we will see some very dramatic further losses,” said Ted Scambos, NSIDC lead scientist.