NOAA's National Centers for Environmental Information
NH Snow Cover Extent
| December 2016 | Snow Cover Extent | Anomaly 1991-2020 | Trend per decade | Rank (51 years) | Record | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| million km² | million mi² | million km² | million mi² | million km² | million mi² | Year(s) | million km² | million mi² | |||
| Northern Hemisphere | 45.40 | 17.53 | +1.13 | +0.44 | +0.40 | +0.15 | Largest | 8th | 2012 | 46.85 | 18.09 |
| Smallest | 44th | 1980 | 37.44 | 14.46 | |||||||
| North America | 17.65 | 6.81 | +0.75 | +0.29 | +0.13 | +0.05 | Largest | 10th | 2009 | 18.27 | 7.05 |
| Smallest | 42nd | 1980 | 14.56 | 5.62 | |||||||
| Ties: 1978 | |||||||||||
| Eurasia | 27.75 | 10.71 | +0.39 | +0.15 | +0.27 | +0.10 | Largest | 12th | 2002 | 29.70 | 11.47 |
| Smallest | 40th | 1980 | 22.88 | 8.83 | |||||||
Data Source: Global Snow Laboratory, Rutgers University. Period of record: 1966–2016 (51 years)
The Northern Hemisphere snow cover extent (SCE) for December 2016 was 45.40 million square km (17.53 million square miles), which is 1.42 million square km (550,000 square miles), or 3.1 percent, larger than the 1981-2010 average. This was eighth largest December SCE in the 51-year period of record for the Northern Hemisphere. December's long term trend (since 1967) is 400,000 square km (150,000 square miles) more SCE per decade. In terms of expansion rate in square miles per decade, December SCE is increasing more than that of any other month on the calendar (November's 360,000 square km per decade is second).
The December North American SCE was 17.65 million square km (6.81 million square miles), which is 800,000 million square km (300,000 square miles), or 4.7% above average and tied December 1978 as the 10th largest on record. Snow cover was more persistent than usual across the northern tier of the United States, from the Pacific Northwest to New England, especially after a storm during the second week of the month. Snow was less persistent than usual south of this tier, which was also generally warmer than normal.
The Eurasian SCE during December was 27.75 million square km (10.71 million square miles), which is 620,000 square km (240,000 square miles), or 2.3% above average. This was the twelfth largest December SCE on record for Eurasia. Snow cover was more persistent than usual in a broad swath from Eastern Europe to the Caucasus to east of the Caspian Sea. Manchurian China saw above-normal snow cover as well. Central and Western Europe observed below-normal snow cover for the month, as did western China.
Sea Ice Extent
| December 2016 | Sea Ice Extent | Anomaly 1991-2020 | Trend per decade | Rank (38 years) | Record | ||||
|---|---|---|---|---|---|---|---|---|---|
| million km² | million mi² | Year(s) | million km² | million mi² | |||||
| Northern Hemisphere | 11.46 | 4.42 | -7.58% | -3.71% | Largest | 37th | 1982 | 13.64 | 5.27 |
| Smallest | 1st | 2016 | 11.46 | 4.42 | |||||
| Southern Hemisphere | 8.28 | 3.20 | -20.38% | +2.02% | Largest | 37th | 2007 | 11.98 | 4.63 |
| Smallest | 1st | 2016 | 8.28 | 3.20 | |||||
| Globe | 19.74 | 7.62 | -13.46% | -1.10% | Largest | 37th | 1988 | 24.69 | 9.53 |
| Smallest | 1st | 2016 | 19.74 | 7.62 | |||||
Data Source: National Snow and Ice Data Center (NSIDC). Period of record: 1979–2016 (38 years)
According to the National Snow and Ice Data Center (NSIDC), the Northern Hemisphere (Arctic) sea ice extent — which is measured from passive microwave instruments onboard NOAA satellites — averaged for December 2016 was 12.09 million square km (4.67 million square miles), which was 1.03 million square km (400,000 square miles), or 7.9 percent, below the 1981-2010 average. This was the second smallest December Arctic sea ice extent on record, just 20,000 square km (roughly 10,000 square miles) larger than the smallest December Arctic sea ice extent, set in 2010. Basinwide, December sea ice extent recovered slightly from the unprecedented large negative anomalies that characterized much of October and November.
As was the case during November, the largest areas of "missing" sea ice, relative to normal, were in the Barents and Chukchi Seas. The Kara Sea saw lower sea ice extent than normal, but not to the extent of that seen in November. Detailed NSIDC analysis for the month.
The December Southern Hemisphere (Antarctic) sea ice extent was 8.83 million square km (3.41 million square miles), which was 2.52 million square km (970,000 square miles), or approximately 22.2 percent, below the 1981-2010 average. This was easily the smallest December Southern Hemisphere sea ice extent on record, 1.09 million square kilometers (420,000 square miles) smaller than the previous record-small December value set in 1982. Even given the large variability characteristic of the Antarctic sea ice extent record, this was a substantial departure from the previous December's value, which was slightly above average. Compared to the long-term average, the December 2016 sea ice "deficit" was nearly double the size of the previous record.
Despite the 2016 value, the long term Southern Hemisphere December sea ice extent is increasing at an average rate of approximately 1.3 percent per decade, albeit with considerable inter-annual variability.
For further information on the Northern and Southern Hemisphere snow and ice conditions, please visit the NSIDC News page.