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Why 2015 Will Be the Hottest Year on Record

It is now all but certain that 2015 will be the hottest year since record keeping began. To better assess what factors played a role in the record heat of 2015, scientists from our World Weather Attribution initiative along with colleagues at the University of Reading performed a simple analysis to determine the driving forces behind this record. Specifically, they looked at the roles of greenhouse gas emissions associated with global warming, the natural climate oscillation known as El Niño, as well as solar activity and volcanic aerosols.

Graphic in °C

According to their analysis, a large majority of the 2015 global surface temperature anomaly is due to anthropogenic forcing, with El Niño playing a smaller supporting role, and solar irradiance an even smaller factor. Volcanoes contribute very little at this time. The remainder is well within the range of variations due to random weather, especially winter weather in Siberia and Canada.