Global Snow and Ice - May 2017


NH Snow Cover Extent

May 2017 Snow Cover Extent 1981-2010 Anomaly Trend
(per decade)
Rank
(out of 51 years)
Records
million km2 million mi2 million km2 million mi2 million km2 million mi2 Year(s) million km2 million mi2
Northern Hemisphere 20.73 8.01 +1.71 +0.66 -0.79 -0.31 Largest 12ᵗʰ 1974 23.09 8.92
Smallest 40ᵗʰ 2010 15.38 5.94
North America 9.76 3.77 +0.46 +0.18 -0.24 -0.09 Largest 18ᵗʰ 1974 11.48 4.43
Smallest 34ᵗʰ 2010 7.80 3.01
Eurasia 10.98 4.24 +1.26 +0.48 -0.55 -0.21 Largest 12ᵗʰ 1976 12.51 4.83
Smallest 40ᵗʰ 2013 7.26 2.80

Data Source: Global Snow Laboratory, Rutgers University. Period of record: 1967–2017 (51 years)

The Northern Hemisphere snow cover extent (SCE) during May was 20.73 million square km (8.01 million square miles), 1.71 million square km (670,000 square miles) above the 1981-2010 average. This was the 12th largest Northern Hemisphere SCE in the 51-year period of record and largest since 1996. The North American and Eurasian SCE were both above average. For the spring season (March-May), the Northern Hemisphere SCE was the 17th largest on record at 870,000 square km (336,000 square miles) above average. This was the largest spring SCE for the Northern Hemisphere since 2003.

During May, the North American SCE was 460,000 square km (180,000 square miles) above the 1981-2010 average — the 18th largest on record. Above-average snow cover was observed for eastern Canada and the Canadian Prairies and parts of eastern Alaska. Below-average snow cover was observed in parts of the American Rockies and western Alaska. The contiguous U.S. SCE was near average, the Canadian SCE was the 11th largest on record, while the Alaska SCE was the 18th smallest. The spring North American SCE was 190,000 square km (73,000 square miles) above average, the 19th largest on record and largest since 2009.

The Eurasian May SCE was 10.98 million square km (4.24 million square miles), 1.26 million square km (490,000 square miles) above average. This ranked as the 12th largest May SCE for Eurasia and the largest since 1985. Above-average snow cover was observed across Scandinavia, western and northern Russia, and parts of the Tibetan Plateau. Below-average snow cover was observed across central and southern Russia, northwestern China and western Turkey. The spring Eurasian SCE was the 16th largest on record at 580,000 square km (224,000 square miles) above average. This was the largest spring SCE for Eurasia since 1996.

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Sea Ice Extent

May 2017 Sea Ice Extent
1981-2010
Anomaly
Trend
(per decade)
Rank
(out of 39 years)
Records
million km2 million mi2 Year(s) million km2 million mi2
Northern Hemisphere 12.74 4.92 -5.28% -2.45% Largest 35ᵗʰ 1985 14.26 5.51
Smallest 5ᵗʰ 2016 12.08 4.66
Southern Hemisphere 9.67 3.73 -10.55% +1.94% Largest 38ᵗʰ 2015 12.15 4.69
Smallest 2ⁿᵈ 1980 9.46 3.65
Globe 22.41 8.65 -7.63% -0.49% Largest 39ᵗʰ 1979 25.52 9.85
Smallest 1ˢᵗ 2017 22.41 8.65

Data Source: National Snow and Ice Data Center (NSIDC). Period of record: 1979–2017 (39 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 May 2017 was 12.74 million square km (4.92 million square miles), 710,000 square km (274,000 square miles), or 5.28 percent, below the 1981-2010 average. This was the fifth smallest May Arctic sea ice extent on record. This ended a seven-month stretch with record-low sea ice extent in the Arctic. The rate of sea ice contraction was slower than average during May with much of the ice loss occurring on the Pacific side of the Arctic with record low sea ice the Chukchi Sea. Sea ice contraction was especially slow on the Atlantic side of the Arctic, with little change in ice coverage in Baffin Bay and Davis Strait and some expansion of ice coverage in the Barents and Greenland Seas. May Arctic ice extent is decreasing at an average rate of 2.5 percent per decade.

The May Southern Hemisphere sea ice extent was 9.67 million square km (3.73 million square miles), which was 1.14 million square km (440,000 square miles), or 10.55 percent, below the 1981-2010 average. This was the second smallest May Southern Hemisphere sea ice extent on record and 210,000 square km (80,000 square miles) larger than the record set in 1980. Below-average sea ice extent continued in the Amundsen Sea, Ross Sea and eastern areas of the Weddell Sea.

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

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Citing This Report

NOAA National Centers for Environmental Information, State of the Climate: Global Snow and Ice for May 2017, published online June 2017, retrieved on August 22, 2017 from https://www.ncdc.noaa.gov/sotc/global-snow/201705.

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