Enviromental problems

Melting Ice in Antarctica Posted September 25, 2007 Large images First Year of Melting (620 kB PNG ) Number of Days of Melting (2005) (600 kB PNG) In places, Antarctica’s rugged, coastal mountain ranges just barely break the surface of a sea of snow and ice thousands of feet thick. On its high, inland plateau sits a sheet of ice more than a mile thick. Massive ice shelves hang off the continent’s into the freezing sea. Even in the summer, most of the continent stays below zero. But even the coldest continent on Earth is melting, say NASA scientists. These maps illustrate different aspects of seasonal melting on the continent. After analyzing 20 years of satellite data, scientists have concluded that persistent melting—melting that lasts for at least three daytime periods or one consecutive day and night—has been occurring increasingly farther inland and at higher altitudes over the past two decades. The top map shows how the area affected by persistent melting has expanded since 1987. The colors represent the first year in which satellites observed persistent melting. Light green shows areas where melting was observed from the beginning, while blue shows areas where melting occurred for the first time more recently. The bottom map shows the number of days on which melting occurred in 2005, a year of particularly dramatic melting. Snow melted as far inland as 500 miles and at altitudes of 1.2 miles above sea level. Not surprisingly, melting lasted longest (dark purple) on the Antarctic Peninsula, which stretches northward away from the continent. The Ross Ice Sheet and the land to its interior also experienced between 10-20 melting days in 2005. Although Antarctica is often shrouded in clouds and experiences months of complete darkness each year, satellites have been able to observe melting on the surface routinely using microwave-frequency observations. Photo-like images of the surface can only be captured in daylight and on clear days, but snow and ice emit microwave frequency energy that passes right through clouds, day and night. Even the smallest amount of liquid water in the snow changes the unique microwave signal given off by the snow Ministers get close look at Antarctic ice threat TROLL RESEARCH STATION, Antarctica — A parka-clad band of environment ministers landed in this remote corner of the icy continent on Monday, in the final days of an intense season of climate research, to learn more about how a melting Antarctica may endanger the planet. Representatives from more than a dozen nations, including the U.S., China, Britain and Russia, were to rendezvous at a Norwegian research station with American and Norwegian scientists coming in on the last leg of a 1,400-mile (2,300-kilometer), two-month trek over the ice from the South Pole. The visitors will gain "hands-on experience of the colossal magnitude of the Antarctic continent and its role in global climate change," said the mission's organizer, Norway's Environment Ministry. They'll also learn about the great uncertainties plaguing research into this southernmost continent and its link to global warming: How much is Antarctica warming? How much ice is melting into the sea? How high might it raise ocean levels worldwide? The answers are so elusive that the Intergovernmental Panel on Climate Change (IPCC), a Nobel Prize-winning U.N. scientific network, excluded the potential threat from the polar ice sheets from calculations in its authoritative 2007 assessment of global warming. The IPCC forecast that oceans may rise up to 23 inches (0.59 meters) this century, from heat expansion and melting land ice, if the world does little to reduce emissions of carbon dioxide and other greenhouse gases blamed for atmospheric warming. But the U.N. panel did not take Antarctica and Greenland into account, since the interactions of atmosphere and ocean with their enormous stores of ice — Antarctica has 90 percent of the world's ice — are poorly understood. And yet the West Antarctic ice sheet, some of whose outlet glaciers are pouring ice at a faster rate into the sea, "could be the most dangerous tipping point this century," says a leading U.S. climatologist, NASA's James Hansen. "There is the potential for several-meter rise of sea level," Hansen told The Associated Press last week. The scenario is "frightening," says the IPCC's chief scientist, Rajendra Pachauri, who met with the ministers in Cape Town before their nine-hour flight here from South Africa. Finding the answers has been key to the 2007-2009 International Polar Year (IPY), a mobilization of 10,000 scientists and 40,000 others from more than 60 countries engaged in intense Arctic and Antarctic research over the past two southern summer seasons — on the ice, at sea, via icebreaker, submarine and surveillance satellite. The 12-member Norwegian-American Scientific Traverse of East Antarctica — the trekkers "coming home" to Troll — was one important part of that work, having drilled deep cores into the annual layers of ice sheet in this little-explored region, to determine how much snow has fallen historically and its composition. Such work will be combined with another IPY project, an all-out effort to map by satellite radar the "velocity fields" of all Antarctic ice sheets over the past two summers, to assess how fast ice is being pushed into the surrounding sea. Then scientists may understand better the "mass balance" — how much the snow, originating with ocean evaporation, is offsetting the ice pouring seaward. "We're not sure what the East Antarctic ice sheet is doing," David Carlson, IPY director, explained last week from the program's offices in Cambridge, England. "It looks like it is flowing a little faster. So is that matched by accumulation? What they come back with will be crucial to understanding the process." The visiting environment ministers were those of Algeria, Britain, Congo, the Czech Republic, Finland, Norway and Sweden. Other countries were represented by climate policymakers and negotiators, including Xie Zhenhua of China and Dan Reifsnyder, a deputy assistant U.S. secretary of state. During their long day here under the 17-hour sunlight of a dying southern summer, when temperatures still drop to near zero Fahrenheit (-20 degrees Celsius), the northern visitors took in the awesome sights of Queen Maud Land, a forbidding, mountainous icescape 3,000 miles (5,000 kilometers) southwest of South Africa, and toured the Norwegians' high-tech Troll Research Station, upgraded to year-round operations in 2005. The politics of climate inevitably mixed with the science. Stranded in Cape Town an extra two days when high Antarctic winds scrubbed a planned weekend flight, the ministers were gently lobbied at lunch and dinner by Scandinavian counterparts favoring urgent action on a new global agreement to succeed the Kyoto Protocol, the deal to reduce greenhouse gases that expires in 2012. President Barack Obama's new U.S. administration has promised action after years of U.S. resistance to the Kyoto process. But the complexity of issues and limited time before a Copenhagen conference in December, target date for a deal, makes the outcome as uncertain as the future of Antarctica's glaciers and offshore ice shelves. Much more research lies ahead, say the scientists, including investigations of the possible warming and shifting currents of the Southern Ocean ringing Antarctica. "We need to put more resources in," said IPY's Carlson. Outspoken scientists say political action may be even more urgently needed. "We are out of out cotton-pickin' minds if we let that process get started," Hansen said of an Antarctic meltdown. "Because there will be no stopping it." Copyright 2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.