Antarctica Compared to Size of US (USGS)
Antarctica’s glaciers are melting more rapidly than previously thought because of climate change, according to new information from US Geological Survey (USGS) through collaboration with the British Antarctic Survey (BAS).
One ice shelf, the Wordie Ice Shelf along the western coast of the Antarctic Peninsula, has completely disappeared. Another, the Larsen Ice Shelf extending along the east coast of the Antarctic Peninsula, has lost a chunk three times the size of Rhode Island.
“The rapid retreat of glaciers there demonstrates once again the profound effects our planet is already experiencing-more rapidly than previously known– as a consequence of climate change,” said US Secretary of the Interior, Ken Salazar.
The Scientific Committee on Antarctic Research (SCAR) reported this week that sea levels are likely to rise more than 4 feet (1.4 meters) by the end of this century, which is twice as much as previously predicted. Still, combining studies of the glacial melts in Greenland — the second largest ice body in the world located in the North Atlantic Ocean and two-thirds within the Arctic circle — and Antarctica raise fears that sea level rise could be much higher than that.
Although current sea level rise has occurred at an average rate of 1.8 mm per year for the past century, current acceleration of the Antarctic ice melt could result in a sea rise that would put many coastal areas under water by 2100. Should the entire west Antarctic ice sheet melt, it would result in a sea rise of well over 10 feet (about 3.3 meters), affecting more than 3.2 billion people worldwide who live within 200 miles of a coastline
Antarctica is the earth’s largest reservoir of glacial ice. Around two per cent (2%) of the land is ice free. The average thickness of the Antarctic ice cap is about 6,600 feet (2,000 meters) and can reach depths up to 13,000 feet (4,000 meters) or more. The ice cap contains approximately 7.2 million cubic miles of frozen fresh water, which is about 70 percent of the world’s fresh water and 90 percent of the world’s ice.
Antarctica began icing about 45.5 million years ago and formed as we know it today about 25 million years ago; however, three million year old fossil evidence of pollen and plankton found high in the Transantarctic Mountains near the coast and dated to around 3 million years ago has provided a theory that Antarctica may have been ice-free and forested at that time. Today, about 98% of the continent – the fifth largest of Earth’s continents – is covered by ice.
The oldest ice core extracted from the Antarctic ice sheet has been dated at over 500,000 years. According to BAS, data extracted from these ice cores show that the climate consists of ice ages and warmer interglacial periods roughly every 100,000 years. These ‘spikes’ within some of the interglacial periods over the last 340,000 years suggest a high level of sensitivity to greenhouse gases at levels similar to those found today.
According to USGS scientists, the ice shelves are especially sensitive to climate change, so their rapid retreat may be a forecast for losses of the land-based ice sheet on the Antarctic continent if warming continues. This could result in sea-level rise, threatening low-lying coastal communities and islands.
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For more information visit the USGS site regarding recent Antarctic melting news.
