Antarctica gaining more ice than it's losing: NASA

Washington: Antarctica is currently gaining enough ice to outweigh the increased losses from the continent's thinning glaciers, a new NASA study has found. The research challenges the conclusions of other studies, including the Intergovernmental Panel on Climate Change's (IPCC) 2013 report, which says that Antarctica is overall losing land ice. According to the new analysis of satellite data, the Antarctic ice sheet showed a net gain of 112 billion tons of ice a year from 1992 to 2001. That net gain slowed to 82 billion tons of ice per year between 2003 and 2008. "We're essentially in agreement with other studies that show an increase in ice discharge in the Antarctic Peninsula and the Thwaites and Pine Island region of West Antarctica," said lead author Jay Zwally, a glaciologist with NASA Goddard Space Flight Centre in US. "Our main disagreement is for East Antarctica and the interior of West Antarctica — there, we see an ice gain that exceeds the losses in the other areas," said Zwally. But it might only take a few decades for Antarctica's growth to reverse, according to Zwally. "If the losses of the Antarctic Peninsula and parts of West Antarctica continue to increase at the same rate they've been increasing for the last two decades, the losses will catch up with the long-term gain in East Antarctica in 20 or 30 years," Zwally said. The study analysed changes in the surface height of the Antarctic ice sheet measured by radar altimeters on two European Space Agency European Remote Sensing (ERS) satellites, spanning from 1992 to 2001, and by the laser altimeter on NASA's Ice, Cloud, and land Elevation Satellite (ICESat) from 2003 to 2008. The extra snowfall that began 10,000 years ago has been slowly accumulating on the ice sheet and compacting into solid ice over millennia, thickening the ice in East Antarctica and the interior of West Antarctica by an average of 1.7 centimetres per year. This small thickening, sustained over thousands of years and spread over the vast expanse of these sectors of Antarctica, corresponds to a very large gain of ice - enough to outweigh the losses from fast-flowing glaciers in other parts of the continent and reduce global sea level rise. "The good news is that Antarctica is not currently contributing to sea level rise, but is taking 0.23 millimetres per year away," Zwally said. "But this is also bad news. If the 0.27 millimetres per year of sea level rise attributed to Antarctica in the IPCC report is not really coming from Antarctica, there must be some other contribution to sea level rise that is not accounted for," Zwally said. The study was published in the Journal of Glaciology. — PTI. Source: Article

Read More........→November 17, 2015

‘Glaciers worldwide melt to lowest levels on record’

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Glaciers worldwide have shrunk to levels not seen in 120 years of record-keeping, with melt-off accelerating in the first decade of the 21st century, according to a study released on Monday. On average, glaciers currently lose between 50 to 150 centimetres of thickness every year, reported the study, published in the Journal of Glaciology. “This is two to three times more than the corresponding average of the 20th century,” said Michael Zemp, director of the World Glacier Monitoring Service and the study’s lead author. More than a billion people, especially in Asia and South America, get more than half of their drinking water from the seasonal melting of snow melt and glacier ice, previous research has shown. The current rate of global glacier melt is without precedent for the 120 years covered by scientific observation, and probably for much longer, Mr Zemp added. Moreover, accelerated ice loss has created a dynamic whereby glaciers in many regions will continue to diminish even if global warming did not continue to boost global temperatures. Preliminary data from the last five years, not covered in the study, suggest that rapid decline of ice mass is continuing apace. The 20th-century record ice loss observed in 1998 “has been exceeded in 2003, 2006, 2011, 2013, and probably again in 2014,” Mr Zemp said. The long-term trend of glacier retreat takes into account shorter periods where, in some locations, glaciers have regained some of their lost ice mass. Many so-called “ice tongues” formed by glacier runoff in Norway, for example, regained a couple hundred metres in length during the 1990s. Overall, though, they have retreated by several kilometres compared to the areas covered in the late 19th century. The World Glacier Monitoring Service compiles the results of worldwide glacier observations submitted annually from a global network of scientists and observers. Glaciers worldwide have shrunk to levels not seen in 120 years of record-keeping, with melt-off accelerating in the first decade of the 21st century, according to a study released on Monday. On average, glaciers currently lose between 50 to 150 centimetres of thickness every year, reported the study, published in the Journal of Glaciology.“This is two to three times more than the corresponding average of the 20th century,” said Michael Zemp, director of the World Glacier Monitoring Service and the study’s lead author. More than a billion people, especially in Asia and South America, get more than half of their drinking water from the seasonal melting of snow melt and glacier ice, previous research has shown. The current rate of global glacier melt is without precedent for the 120 years covered by scientific observation, and probably for much longer, Mr Zemp added. Moreover, accelerated ice loss has created a dynamic whereby glaciers in many regions will continue to diminish even if global warming did not continue to boost global temperatures. Preliminary data from the last five years, not covered in the study, suggest that rapid decline of ice mass is continuing apace. The 20th-century record ice loss observed in 1998 “has been exceeded in 2003, 2006, 2011, 2013, and probably again in 2014,” Mr Zemp said. The long-term trend of glacier retreat takes into account shorter periods where, in some locations, glaciers have regained some of their lost ice mass. Many so-called “ice tongues” formed by glacier runoff in Norway, for example, regained a couple hundred metres in length during the 1990s. Overall, though, they have retreated by several kilometres compared to the areas covered in the late 19th century. The World Glacier Monitoring Service compiles the results of worldwide glacier observations submitted annually from a global network of scientists and observers.‘Source: The Asian Age

Read More........→August 05, 2015