Facts about sea ice

The National Snow and Ice Data Center provides daily updates on the status of sea ice extent in both the Arctic and Antarctic regions.

Below is the most recent plot of sea ice extent in both the Arctic and Antarctic compared to the 1981-2010 average. FYI: The 2012 plot on the Arctic sea ice graph was the year of the record low sea ice minimum.

<img src="https://vortex.accuweather.com/adc2004/pub/includes/columns/climatewx/2017/590x472_05031630_n_iqr_timeseries-(1).png"/>

<img src="https://vortex.accuweather.com/adc2004/pub/includes/columns/climatewx/2017/590x472_05031631_s_iqr_timeseries.png"/>

Sea ice is frozen ocean water. When it melts, it does not add to the sea level.

Icebergs, glaciers and ice shelves float in the ocean but originate on land. When they melt, they contribute to sea level rise.

Around 80 percent of the sunlight that strikes the surface of sea ice is <strong>reflected</strong> back into space. When sea ice melts it exposes the darker, colored ocean surface, which <strong>absorbs</strong> 90 percent of the sunlight. As the oceans heat up, the Arctic temperatures rise.

Sea ice extent is a measurement of the area where there is at least 15 percent coverage of sea ice. Satellites and ground measurements are used to determine sea ice extent.

The Arctic melt season typically begins in March and ends in September with the annual minimum extent. The date of the annual minimum has trended later in recent years due to a lengthening melt season.

Key excerpt from the <a href="https://nsidc.org/cryosphere/quickfacts/seaice.html" target=n>NSIDC sea ice page.</a>

<em>Changes in the timing of the sea ice minimum extent are especially important because more of the sun's energy reaches Earth's surface during the Arctic summer than during the Arctic winter. As explained above, sea ice reflects much of the sun's radiation back into space, whereas dark, ice-free ocean water absorbs more of the sun's energy. So, reduced sea ice during the sunnier summer months has a big impact on the Arctic's overall energy balance.</em>

Report a Typo