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||
(out of 40 years)
|million km2||million mi2||Year(s)||million km2||million mi2|
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.