Green Snowflake

The WAIS

With an estimated volume of 2.2 million km3, the West Antarctic Ice Sheet is one of the largest repositories of fresh water ice in the world.  And unfortunately, it's losing mass at an alarming rate, to the tune of 121 billion tons per year!  There has been a 75% increase in the loss of ice over the past twenty years.  If the ice sheet were to fail completely and slip into the ocean, global sea levels would rise by 15 feet (4.8 meters), resulting in catastrophic conditions for coastal areas.

 

Polar ice experts are just now beginning to pay increased attention to the West Antarctic Ice Sheet, but we believe more action is needed before the situation becomes irreversible.  Westarctica is dedicated to educating the public about the melting Antarctic icecap and showing people that they can prevent rising sea levels by taking simple steps right in their own home!

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The Western Antarctic Ice Sheet (WAIS) is the segment of the continental ice sheet that covers Western Antarctica and the portion of Antarctica on the side of the Transantarctic Mountains which lies in the Western Hemisphere. The WAIS is classified as a marine-based ice sheet, meaning that its bed lies well below sea level and its edges flow into floating ice shelves. The WAIS is bounded by the Ross Ice Shelf, the Ronne Ice Shelf, and outlet glaciers that drain into the Amundsen Sea.

 

It is estimated that the volume of the Antarctic ice sheet is about 25.4 million km3 (6.1 million cu mi), and the WAIS contains just under 10% of this, or 2.2 million km3 (530,000 cu mi). The weight of the ice has caused the underlying rock to sink by between 0.5 and 1 kilometer (0.31 and 0.62 miles) in a process known as isostatic depression.

 

Under the force of its own weight, the ice sheet deforms and flows. The interior ice flows slowly over rough bedrock. In some circumstances, ice can flow faster in ice streams, separated by slow-flowing ice ridges. The inter-stream ridges are frozen to the bed while the bed beneath the ice streams consists of water-saturated sediments. Many of these sediments were deposited before the ice sheet occupied the region, when much of West Antarctica was covered by the ocean.

 

When ice reaches the coast, it either calves or continues to flow outward onto the water. The result is a large, floating ice shelf affixed to the continent.

The West Antarctic Ice Sheet has warmed by more than 0.1 °C (0.18 °F)/decade in the last fifty years, and the warming is the strongest in winter and spring. Although this is partly offset by fall cooling in East Antarctica, this effect was restricted to the 1980s and 1990s.

 

The continent-wide average surface temperature trend of Antarctica is positive and statistically significant at >0.05 °C (0.090 °F)/decade since 1957. This warming of WAIS is strongest in the Antarctic Peninsula.

 

In 2012, the temperature records for the ice sheet were reanalyzed with a conclusion that since 1958, the West Antarctic ice sheet had warmed by 2.4 °C (4.3 °F), almost double the previous estimate. Some scientists now fear that the WAIS could now collapse like the Larsen-B Ice Shelf did in 2002.

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