지구 온난화 현상으로 가장 큰 걱정중 하나가, 만약에 북극의 얼음물이 지구 온난화 때문에 녹아 내리면 지구상의 해안에 건설된 여러 도시들이 홍수를 피할길 없게하는,얼은물의 보관소 라고 할수 있는 북극물이 녹아 내릴 가능성이 한층 높아 졌다. 남극 대륙의 얼음이 녹아 내리면 해면의 수위가 60 미터 높아져 이로인해 수백만명이 홍수에 휩쓸리고 해안 도시들을 물속에 잠기게 할만큼의 얼음이 쌓여 있다. 이러한 얼음덩이들이 커지게 될지, 반대로 줄어들지 또는 그대로 현상유지될지, 과학자들 사이에서도 어떤 현상이 일어날지 합의점을 찾지 못하는, 큰 걱정이 깊이 짖누르고 있다한다. 그러나 지금까지 발표됐던 그 어떤 보고서보다 더 많은 연구 자료를 기초로 해서 만든 남극 대륙의 보고서가 오늘 발표 됐는데, 그내용이 걱정으로 꽉 차있었다. 즉 북극의 얼음창고는 1996년부터 2006년 사이에 상상할수 없을 정도로 빠르게 줄어들고 있다는 내용이다. "우리의 탐사기간동안에도 얼음창고(Ice Sheet)는 계속 줄어 들고 있었고, 그 줄어든 양이 지난 10년 동안에 75%나 증가 했다"라고 보고서는 설명한다. 하나 희망을 주는 소식은 동편쪽의 북극해 얼음은 극히 정상적으로 유지 되고 있었고, 오히려 크기면에서는 커지고 있다는 것이다. 아래 원문 참조 하시면 더많은 내용을 보실수 있읍니다. Antarctic ice sheet shrinking at faster rate MARTIN MITTELSTAED Globe and Mail Update January 13, 2008 at 1:00 PM EST One of the biggest worries about global warming has been its potential to affect the stability of the Antarctic ice sheet, a vast storehouse of frozen water that would inundate the world's coastal regions if it were to melt because of a warming climate. The southern continent contains enough ice to raise ocean levels by about 60 metres, a deluge that would put every major coastal city in the world deep under water and uproot hundreds of millions of people. The huge implications posed by the health of the ice sheet have prompted major scientific interest into whether it is growing, shrinking, or stable, with no clear consensus among researchers about its overall trend. But a new study released today, based on some of the most extensive measurements to date of the continent's ice mass, presents a worrisome development: Antarctica's ice sheet is shrinking, at a rate that increased dramatically from 1996 to 2006. "Over the time period of our survey, the ice sheet as a whole was certainly losing mass, and the mass loss increased by 75 per cent in 10 years," the study said. The results of the research project, led by Dr. Eric Rignot, principal scientist for the Radar Science and Engineering Section at NASA's Jet Propulsion Laboratory's in Pasadena, Calif., appear in the current issue of Nature Geoscience. In an e-mail, Dr. Rignot attributed the shrinkage in the ice sheet to an upwelling of warm waters along the Antarctic coast, which is causing some glaciers to flow more rapidly into the ocean. He suspects the trend is due to global warming, and isn't part of a normal natural fluctuation. "I see that as the main driver for the change in ice mass. And this means that we are not in a natural cycle but in something that is related to global warming or global climate change, whichever you want to call it," he said. The study said the continent had a net lost of about 196 billion tonnes of ice in 2006, an amount that is equal more than a third of the water in Lake Erie, up from 112 billion tonnes in 1996. The figures were calculated by deducting the amount of ice losses on the continent from the amount of snow computer models indicate it receives. The figures were based on satellite data on ice thickness and the speeds at which glaciers are flowing into the ocean. Dr. Rignot said the Antarctic ice loss in 2006 raised sea levels about half a millimetre, putting it on par with the contribution to sea level rise from the recently observed melting of the Greenland ice sheet. Within scientific circles, there is little doubt that Greenland's ice is melting, but there has been more uncertainty over the fate of the larger stores of ice on Antarctica. The authoritative Intergovernmental Panel on Climate Change, the UN-sponsored scientific body that compiles information on global warming, said last year that studies on the subject have been all over the map. Some have suggested the ice cap was expanding by 50 billion tonnes a year from 1993 to 2003, while others projected losses over the same period of up to 200 billion tonnes. It said the wide range of estimates reflected such factors as the small number of ice measurements made on the continent and disagreements among scientists on what techniques are best to estimate the trends there. Some experts have even speculated that global warming might lead to increases in ice accumulation in Antarctic's interior due to more snowfall. However, many experts say that this effect is unlikely to offset Antarctica's contribution to sea level rise because of the rapid melting of coastal glaciers. "The concept that global warming will increase precipitation in Antarctica and mitigate sea level rise is a lullaby," Dr. Rignot said. "Our story shows that the main driver for the mass balance is the rate of glacier flow to the sea, not the precipitation rate because other studies already showed recently that the precipitation rate has not changed significantly." Another member of the research team, Curt Davis, director of the Centre for Geospatial Intelligence at the University of Missouri-Columbia, said the new study is the "most comprehensive" to date on the status of Antarctica's ice, and has zeroed in on exactly where the losses are occurring. It found that the biggest losses are in West Antarctica, around the Amundsen Sea, and in the Antarctic Peninsula, the continent's distinctive long arm of land that points like a finger up at South America. One encouraging finding from the study is that the largest ice sheet, the one covering East Antarctica, has remained relatively stable, showing a small net gain in size.