From the National Snow and Ice Data Center (NSIDC)

Sea ice in the Arctic and the Antarctic set record low extents every day in December, continuing the pattern that began in November. Warm atmospheric conditions persisted over the Arctic Ocean, notably in the far northern Atlantic and the northern Bering Sea. Air temperatures near the Antarctic sea ice edge were near average. For the year 2016, sea ice extent in both polar regions was at levels well below what is typical of the past several decades.
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Arctic sea ice extent for December 2016 averaged 12.10 million square kilometers (4.67 million square miles), the second lowest December extent in the satellite record. This is 20,000 square kilometers (7,700 square miles) above December 2010, the lowest December extent, and 1.03 million square kilometers (397,700 square miles) below the December 1981 to 2010 long-term average.
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Through 2016, the linear rate of decline for December is 44,500 square kilometers (17,200 square miles) per year, or 3.4 percent per decade.

http://nsidc.org/arcticseaicenews/files/2017/01/Figure3-350×270.png