After record warm surface temperatures in 2014 and 2015, these records were beaten in 2016. The record warm year will come as no surprise to anyone watching the weather reports over the course of 2016. Jeff Masters and Bob Henson at Weather Underground put the temperature records in the context of the weather in 2016: Confirmed: 2016 the Warmest Year in History of Global Recordkeeping.
The warming climate is seen most emphatically in the Arctic Ocean. Sea ice measures there set new record lows for most of the days in 2016, and that is a trend that continues to the present. Largely by coincidence, sea ice levels around Antarctica too are at record lows, generating an all-time low in global sea ice. The state of sea ice, from an Arctic perspective, was summarized by Neven last week: Global sea ice records broken (again). One effect of a warming climate is a new trend of major winter storms in the Arctic Ocean. Currently one such storm is breaking up the edge of the ice on the Atlantic side. At the same time, winds are pushing ice out into the Greenland Sea and the Bering Sea at opposite corners of the Arctic Ocean. In the past, we haven’t had to worry about winter disturbances creating a lasting effect on sea ice in the Arctic Ocean because as long as the weather settles into normal winter cold by around January 19, there is enough winter remaining to build a respectable ice pack. This winter could be the one that breaks that pattern. Ice measures, already at record lows, have stalled since January 7 and the weather forecast shows no indication of a quick return to normal winter weather. With persistent warm conditions, 2017 could be the first year in which the Arctic Ocean reaches the beginning of spring with ice weakened by a short winter.