Record Warming Global Mean Surface Temperature in 2014-2016 Related to Large Oceanic Heat Releases

A 0.24°C increase of record warm global mean surface temperature (GMST) over 2014-2016 was highly unusual and largely a consequence of an El Niño that released unusually large amounts of ocean heat from the subsurface layer of the northwestern tropical Pacific. This heat had built up since the 1990s mainly due to greenhouse-gas (GHG) forcing and possible remote oceanic effects. Model simulations and projections suggest that the fundamental cause, and robust predictor of large record-breaking events of GMST in the 21st century, is GHG forcing rather than internal climate variability alone. Such events are projected to increase in the future under elevated GHG forcing.