May 2014 Global Snow and Ice Report

NH Snow Cover Extent

Data Source: Global Snow Laboratory, Rutgers University. Period of record: 1967–2014 (48 years)

May's Northern Hemisphere
Snow Cover Extent plot

The Northern Hemisphere snow cover extent (SCE) during May 2014 was 17.01 million square km (6.57 million square miles), which was 2.01 million square km (770,000 square miles) below the 1981-2010 average. This marked the sixth smallest May SCE on record for the Northern Hemisphere, and the third consecutive month that the Northern Hemisphere SCE ranked as the sixth smallest for each respective month. Both the Eurasian and North American SCE were also below average during May. The Northern Hemisphere snow cover extent during May is decreasing at an average rate of 0.9 million square km [0.3 million square miles (4.5 percent)] per decade. During the Northern Hemisphere spring (March-May), the Northern Hemisphere SCE was 1.8 million square km (700,000 square miles) below the 1981-2010 average, and the third smallest spring SCE for the hemisphere. Only the spring seasons of 1968 and 1990 had smaller spring SCE for the Northern Hemisphere.

May's North America
Snow Cover Extent plot

During May, the North American SCE was 8.7 million square km (3.4 million square miles), 550,000 square km (210,000 square miles) below the 1981-2010 average, and the 11^th smallest May SCE on record for the continent. During May, below-average snow cover was observed across northern parts of the U.S. Rockies, northwestern Canada, and much of Alaska. Above-average snow cover was observed in parts of the central U.S. Rockies, the Canadian Prairies, eastern Canada, and the North Slope of Alaska. Overall, the contiguous U.S. and Canada both had a slightly below-average May SCE, while Alaska had its smallest May SCE on record at 650,000 square km (250,000 square miles), 1.0 million square km (385,000 square miles) below average. The record small SCE in Alaska was due in part to a very warm spring across the state, with below-average precipitation in southern and interior regions. For the spring season, the North American SCE was 250,000 square km (97,000 square miles) above the 1981-2010 average, and the 20^th largest (29^th smallest) spring SCE on record.

May's Eurasia
Snow Cover Extent plot

The Eurasian SCE during May was 8.26 million square km (3.19 million square miles), which was 1.46 million square km (560,000 square miles) below the 1981-2010 average and the sixth smallest Eurasian May SCE on record. This was the largest May SCE on record for Eurasia since 2009. Below-average snow cover was observed across much of Russia, the Alps, and parts of the Tibetan Plateau. Above-average snow cover was observed in northern Scandinavia, parts of northern Russia, and south-central China. For the spring season, the fourth smallest March SCE, record smallest April SCE, and sixth smallest May SCE led to the second smallest spring SCE on record for Eurasia. The seasonal SCE was 2.05 million square km (790,000 square miles) below the 1981-2010 average. Only the spring SCE of 2009 was smaller at 2.14 million square km (825,000 square miles) below average.

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Sea Ice Extent

Data Source: National Snow and Ice Data Center (NSIDC). Period of record: 1979–2014 (36 years)

May's Northern Hemisphere
Sea Ice Extent plot

According to the National Snow and Ice Data Center (NSIDC), the Northern Hemisphere sea ice extent — which is measured from passive microwave instruments onboard NOAA satellites — averaged for May 2014 was 12.78 million square km (4.93 million square miles), 610,000 square km (240,000 square miles), or 4.6 percent, below the 1981-2010 average, and the third smallest May Arctic sea ice extent on record. Only the May Arctic sea ice extents of 2004 and 2006 were smaller. The rate of ice decline during May across the Arctic was near average, with sea ice retreating most rapidly in the northern Bering Sea and southern Chukchi Sea. According to the NSIDC, high concentrations of sea ice were observed during May across the Arctic compared to the same month during 2007 and 2012 when record low sea ice minimums were observed in September of those years. Overall, May Arctic sea ice extent is decreasing at an average rate of 2.2 percent per decade.

May's Southern Hemisphere
Sea Ice Extent plot

The May 2014 Southern Hemisphere sea ice extent was 12.03 million square km (4.64 million square miles), 1.24 million square km (470,000 square miles), or 11.5 percent, above the 1981-2010 average. This ranked as the largest Antarctic sea ice extent on record, surpassing the May 2000 Antarctic sea ice extent by 370,000 square km (140,000 square miles), approximately the size of Japan. This marked the 17^th consecutive month with much above average sea ice extent in the Southern Hemisphere and the second consecutive month with record large sea ice. In fact, six of the last 12 months have had record large sea ice extent in the Southern Hemisphere. Much of the above-average ice extent occurred in the Weddell Sea off the West Antarctic coast, with above-average sea ice in nearly every region. Southern Hemisphere sea ice extent during May is increasing at an average rate of 2.5 percent per decade with substantial interannual variability.

When combining the Northern and Southern Hemisphere sea ice extents, the globally-averaged sea ice extent during May was 24.81 million square km (9.58 million square miles), 2.6 percent above the 1981-2010 average and the sixth largest May global sea ice extent on record. Global sea ice extent during May is decreasing at an average rate of 0.1 percent per decade.

For further information on the Northern and Southern Hemisphere snow and ice conditions, please visit the NSIDC News page.

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