Sea Ice

Sea ice refers to ice that is formed from saltwater and floats on the ocean’s surface. It is found mostly in polar regions.

The disappearance of sea ice is attributed to climate warming caused by an increase of greenhouse gases in the atmosphere.

Which Goals Does This Affect?

Minimum Extent of Sea Ice: 1985 – 2005 (highlighted (3) years, 1990, 2000, 2009)    

Arctic Sea Ice
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How Was It Measured?

The Ocean Health Index measures historical extent (area) of sea ice using sea ice concentrations from the U.S. National Snow and Ice Data Center from 1996 to present. Data are 25km in resolution (625km2 per pixel) in a stereographic polar projection. Status was calculated as the smoothed average of the percent of monthly pixels with ice concentrations of 15% or more during specified 3-year periods.

What Are The Impacts?

Biodiversity of Sea Ice
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Sea ice creates a barrier between the ocean and the atmosphere, helping to cool the atmosphere by up to 30% (Bradtmiller and Ali).

Sea ice protects the ocean from extreme arctic cold, keeping sub-ice water warmer than it would otherwise be.

Microscopic algae grow at the sea-ice interface, providing the base of a productive under-ice food web and accelerating the spring bloom of plankton when the ice melts and releases its algal coating into the water column.

A wide variety of Arctic and Antarctic species rely on sea ice as an essential habitat.
Sea ice acts as a protective barrier against the impact of waves on arctic coastlines.

A lack of sea ice can lead to extensive shoreline erosion, resulting in the forced relocation of coastal communities.
Despite its key importance to Arctic biodiversity and coastal protection, extensive melting of sea ice caused by climate change is creating enormous economic opportunities for northern nations by creating new shipping routes between the Atlantic and Pacific Oceans and by offering the opportunity for oil, gas and mineral exploration in newly ice-free regions.

Get More Information

National Snow & Ice Data Center (NSIDC)
Sea Ice Index: provides extensive information on the nature and formation of sea ice.


PHOTO(S): © Keith A. Ellenbogen
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