This sixth edition of explaining extreme events of the previous year (2016) from a climate perspective is the first of these reports to find that some extreme events were not possible in a preindustrial climate.
According to CMIP5 simulations, the 2016 record global warmth was only possible due to substantial centennial-scale anthropogenic warming. Natural variability made a smaller contribution to the January–December 2016 annual-mean global temperature anomaly.
The 2016 Alaska marine heat wave was unprecedented in terms of sea surface temperatures and ocean heat content, and CMIP5 data suggest human-induced climate change has greatly increased the risk of such anomalies.
The 2016 extreme warmth across Asia would not have been possible without climate change. The 2015/16 El Niño also contributed to regional warm extremes over Southeast Asia and the Maritime Continent.