Global Snow and Ice - October 2017


Beginning in November 2017, NCEI will use version 3 of the National Snow and Ice Data Center's (NSIDC) monthly sea ice extent index. All historical monthly sea ice extent values will be updated to version 3, but historical reports will not be updated. For additional information on the methodology changes and comparisons to version 2, please visit the National Snow and Ice Data Center.

NH Snow Cover Extent

October 2017 Snow Cover Extent 1981-2010 Anomaly Trend
(per decade)
Rank
(out of 50 years)
Records
million km2 million mi2 million km2 million mi2 million km2 million mi2 Year(s) million km2 million mi2
Northern Hemisphere 21.17 8.17 +3.63 +1.40 +0.37 +0.14 Largest 9ᵗʰ 1976 25.72 9.93
Smallest 42ⁿᵈ 1988 12.78 4.93
North America 9.12 3.52 +1.07 +0.41 +0.13 +0.05 Largest 7ᵗʰ 2002 9.76 3.77
Smallest 44ᵗʰ 1979 6.36 2.46
Eurasia 12.05 4.65 +2.55 +0.99 +0.24 +0.09 Largest 11ᵗʰ 1976 17.22 6.65
Smallest 40ᵗʰ 1988 5.58 2.15

Data Source: Global Snow Laboratory, Rutgers University. Period of record: 1967–2017 (50 years)

The Northern Hemisphere snow cover extent (SCE) for October 2017 was 21.17 million square km (8.17 million square miles), which was 3.63 million square km (1.40 million square miles), or 20.7 percent, larger than the 1981-2010 average. This was the ninth largest October SCE in the 50-year period of record for the Northern Hemisphere. Each of the last six Octobers, beginning with October 2012, has seen above-average Northern Hemisphere SCE values. Despite the above-average monthly SCE, this was the smallest October value since since 2013. October's long term trend (since 1967) is +2.1% more SCE per decade, the largest such upward trend of any month.

The October North American SCE was 9.12 million square km (3.52 million square miles), 1.07 million square km (410,000 square miles) above average and the seventh largest on record. This is the sixth consecutive October with above average North American SCE. Snow cover was above average for much of Canada, interior Alaska, and parts of the U.S. High Plains. Below-average SCE was observed in western Alaska, parts of the southern Canadian Rockies, and northern U.S. Rockies to northern High Plains. The contiguous U.S. SCE was the 17th largest on record, the Canadian SCE was the sixth largest on record, while the Alaskan SCE was the 19th largest.

The Eurasian SCE during October was 12.05 million square km (4.65 million square miles), which is 2.55 million square km (0.98 million square miles) above average. This was the 11th largest October SCE on record for Eurasia. Above-average SCE was observed across much of Asia, and was particularly so across most of Russia, Scandinavia, central China, northern Mongolia, and northern Kazakhstan. Below-average SCE was observed across Tibet, and parts of the Hindu Kush mountains.


[ top ]


Sea Ice Extent

October 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 6.71 2.59 -19.64% -9.10% Largest 35ᵗʰ 1986 9.48 3.66
Smallest 5ᵗʰ 2012 5.89 2.27
Southern Hemisphere 17.70 6.83 -2.21% +0.72% Largest 35ᵗʰ 2013 19.02 7.34
Smallest 5ᵗʰ 1986 17.18 6.63
Globe 24.41 9.42 -7.68% -2.34% Largest 38ᵗʰ 1980 27.75 10.71
Smallest 2ⁿᵈ 2016 23.43 9.05

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 October 2017 was 6.71 million square km (2.59 million square miles), 1.64 million square km (633,000 square miles), or 19.6 percent, below the 1981-2010 average. This was the fifth smallest October Arctic sea ice extent on record and 820,000 square kilometers (320,000 square miles) above the record low October extent set in 2012. The overall expansion of sea ice was faster than average throughout the month, but sea ice extent continued to be below-average throughout much of the Arctic, particularly in the Chukchi, Kara, and Barents Seas. Since 1979, October Arctic sea ice extent is decreasing at an average rate of 9.1 percent per decade.

The October Southern Hemisphere (Antarctic) sea ice extent was 17.70 million square km (6.83 million square miles), which was 400,000 square km (160,000 square miles), or 2.21 percent, below the 1981-2010 average. This was the fifth smallest October Southern Hemisphere sea ice extent on record. Southern Hemisphere October sea ice extent is increasing at an average rate of 0.7 percent per decade. On October 11 and 12, the Antarctic sea ice extent reached its annual maximum extent at 17.98 million square km (6.96 million square miles). This was the second smallest Antarctic sea ice extent maximum on record — only slightly larger than the maximum extent in 1986. The date tied with 2002 as the latest date of occurrence of the annual maximum.

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

[ top ]


Citing This Report

NOAA National Centers for Environmental Information, State of the Climate: Global Snow and Ice for October 2017, published online November 2017, retrieved on November 21, 2017 from https://www.ncdc.noaa.gov/sotc/global-snow/201710.

Metadata