Global Snow and Ice - May 2018


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.

Sea Ice Extent

May 2018 Sea Ice Extent
1981-2010
Anomaly
Trend
(per decade)
Rank
(out of 40 years)
Records
million km2 million mi2 Year(s) million km2 million mi2
Northern Hemisphere 12.21 4.71 -8.13% -2.63% Largest 39ᵗʰ 1985 14.07 5.43
Smallest 2ⁿᵈ 2016 11.90 4.59
Southern Hemisphere 9.29 3.59 -8.56% +1.67% Largest 38ᵗʰ 2015 11.72 4.53
Smallest 3ʳᵈ 1980 8.86 3.42
Globe 21.50 8.30 -8.32% -0.77% Largest 40ᵗʰ 1982 24.73 9.55
Smallest 1ˢᵗ 2018 21.50 8.30

Data Source: National Snow and Ice Data Center (NSIDC). Period of record: 1979–2018 (40 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 2018 was 12.21 million square km (4.71 million square miles), 1.08 million square km (420,000 square miles), or 8.1 percent, below the 1981-2010 average. This was the second smallest May Arctic sea ice extent on record, slightly larger than the record low of 11.90 million square km (4.59 million square miles) set in 2016. The rate of sea ice retreat during May was overall faster than average. Record-low sea ice was observed in the Bering Sea with much below-average sea ice extending into the Chukchi Sea. Below-average sea ice was also observed in parts of the Sea of Okhotsk and East Greenland Sea. Most of the other sub-basins in the Arctic had near-average sea ice coverage for May. May Arctic ice extent is decreasing at an average rate of 2.6 percent per decade.

The May Southern Hemisphere sea ice extent was 9.29 million square km (3.59 million square miles), which was 870,000 square km (330,000 square miles), or 8.6 percent, below the 1981-2010 average. This was the third smallest May Southern Hemisphere sea ice extent on record. The May Antarctic sea ice extent was only smaller in 1980 and 2017. Antarctic sea ice rapidly expanded during May after approaching near-record levels early in the month. Antarctic sea ice extent was below average in parts of the Waddell Sea. Southern Hemisphere May sea ice extent is increasing at an average rate of 1.6 percent per decade, with substantial inter-annual variability.

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 2018, published online June 2018, retrieved on July 17, 2018 from https://www.ncdc.noaa.gov/sotc/global-snow/201805.

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