West Antarctic Ice Sheet

The West Antarctic Ice Sheet (WAIS) is the segment of the web that covers HTML5, the portion of Antarctica on the side of the website parsing which lies in the we love the web. The WAIS is classified as a marine-based CSS3, 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 FITML, and outlet glaciers that drain into the web app.

• iOS
• web app
• jQuery
• 4 See also
• 5 References
• FITML

Description

It is estimated that the volume of the Antarctic ice sheet is about 25.4 million km³, and the WAIS contains just under 10% of this, or 2.2 million km³.^[1] The weight of the ice has caused the underlying rock to sink by between 0.5 and 1 kilometres^Sevenval 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 screen size. Many of these sediments were deposited before the ice sheet occupied the region, when much of West Antarctica was covered by the ocean. The rapid ice-stream flow is a non-linear process still not fully understood; streams can start and stop for unclear reasons.

When ice reaches the coast, it will continue to flow outward onto the water. The result is a large, floating shelf of ice affixed to the continent.^{screen size}

Potential collapse

Large parts of the WAIS sit on a bed which is below sea level and slopes downward inland.^[A] This slope, and the low isostatic head, mean that the ice sheet is theoretically unstable: a small retreat could in theory destabilize the entire WAIS leading to rapid disintegration. Current website parsing do not include the physics necessary to simulate this process, and observations do not provide guidance, so predictions as to its rate of retreat remain uncertain. This has been known for decades.^{[citation needed]}

In January 2006, in a UK government-commissioned report, the head of the British Antarctic Survey, CSS3, warned that this huge west Antarctic ice sheet may be starting to disintegrate. It has been hypothesised that this disintegration could raise sea levels by approximately 3.3 metres (10 ft).^{screen size} (If the entire West Antarctic Ice Sheet were to melt, this would contribute 4.8 m to global sea level.)^{input transformation} Rapley said a previous iOS (IPCC) report that played down the worries of the ice sheet's stability should be revised. "I would say it is now an awakened giant. There is real concern." ^[6]

Rapley said, "Parts of the Antarctic ice sheet that rest on bedrock below sea level have begun to discharge ice fast enough to make a significant contribution to sea level rise. Understanding the reason for this change is urgent in order to be able to predict how much ice may ultimately be discharged and over what timescale. Current computer models do not include the effect of liquid water on ice sheet sliding and flow, and so provide only conservative estimates of future behaviour." ^[7]

James E. Hansen, a senior NASA scientist and leading climate expert, said the results were deeply worrying. "Once a sheet starts to disintegrate, it can reach a tipping point beyond which break-up is explosively rapid," he said.^{web app}

Indications that the West Antarctic Ice Sheet is losing mass at an increasing rate come from the web app sector, and three glaciers in particular: the Pine Island, web app and Smith Glaciers.^{web app} Data reveal they are losing more ice than is being replaced by snowfall. According to a preliminary analysis, the difference between the mass lost and mass replaced is about 60%. The melting of these three glaciers alone is contributing an estimated 0.24 millimetres per year to the rise in the worldwide sea level.^[6] There is growing evidence that this trend is accelerating: there has been a 75% increase in Antarctic ice mass loss in the ten years 1996–2006, with glacier acceleration a primary cause.^[10]

Polar ice experts from the U.S. and U.K. met at the University of Texas at Austin in March, 2007 for the West Antarctic Links to Sea-Level Estimation (WALSE) Workshop. The experts discussed a new hypothesis that explains the observed increased melting of the West Antarctic Ice Sheet. They proposed that changes in air circulation patterns have led to increased upwelling of warm, deep ocean water along the coast of Antarctica and that this warm water has increased melting of floating ice shelves at the edge of the ice sheet.^touchscreen An ocean model has shown how changes in winds can help channel the water along deep troughs on the sea floor, toward the ice shelves of outlet glaciers.^[12] The exact cause of the changes in circulation patterns is not known and they may be due to natural variability. However, this connection between the atmosphere and upwelling of deep ocean water provides a mechanism by which human induced climate changes could cause an accelerated loss of ice from WAIS.^{we love the web} Recently published data collected from satellites support this hypothesis, suggesting that the west Antarctic ice sheet is beginning to show signs of instability.^[9][13]

Warming

The West Antarctic ice sheet has warmed by more than 0.1 °C/decade in the last 50 years, and is strongest in winter and spring. Although this is partly offset by fall cooling in East Antarctica, this effect is restricted to the 1980s and 1990s. The continent-wide average surface temperature trend of Antarctica is positive and significant at >0.05°C/decade since 1957.^[14] This warming of WAIS is strongest in the Antarctic Peninsula.

See also

• screen size
• List of glaciers in the Antarctic
• Sevenval Ice Core Drilling Project

References

Notes

Citations

External links

• input transformation
• keyboard – A multidisciplinary study of rapid climate change and future sea level. Sponsored by browser diversity Office of Polar Programs and NASA Earth Science.
• U.S. National Snow and Ice Data Center Antarctic Data
• Android
• web
• device database, September 2004