For more recent images from 2005, please visit IOTD/ view.php?id=43466.Īnisimov, O.A., D.G. Available online at news/ press/ larsen_B/ 2002_animation.html. Images courtesy of the National Snow and Ice Data Center. The shrinking sea ice cover has probably contributed to the diminished abundance of krill in the Southern Ocean west of the Antarctic Peninsula, which is expected to affect predators such as albatrosses, seals, whales, and penguins. 2 Invasion by non-native species has already occurred on many sub-Antarctic islands, with negative effects on resident species. If climate change continues unabated, summer warming in the Antarctic Peninsula is expected to expose rock and permafrost-which are then likely to provide habitat for alien flora and fauna. 6 The amount of water locked up in the West Antarctic and East Antarctic ice sheets has the potential to raise global sea levels 173 feet (52.8 meters.) 6 If only the most vulnerable parts of the West Antarctic ice sheet collapse, scientists project that global sea level is likely to rise by nearly 11 feet (3.3 meters)-with consequences for coastlines worldwide, including along the Pacific and Atlantic seaboards of the United States. The largest unknown for scientists projecting sea-level rise over the next century is the extent of melting of the great ice sheets of Antarctica and Greenland. Continued warming of the Antarctic Peninsula is also likely to have a substantial impact on the region's unique terrestrial and marine ecosystems. The melting also has implications for sea life, fishing industries, and coastal communities around the world. The melting of the Antarctic ice shelves is both affected by climate change and contributes to it. Melting of the Antarctic ice sheets very likely contributed to the significant acceleration of sea-level rise from 1993 to 2003. The land ice trapped in glaciers then start to flow more rapidly toward the ocean, which contributes to sea-level rise. While the collapse of an ice shelf floating on the ocean, such as Larsen B, does not in itself raise sea level, it removes a barrier between 'tidewater' glaciers and the ocean. 14 This suggests that recent warming in the region is unique in the past 10,000 years. 2, 11 These ice shelves have not been as small as they are now for at least 1,000 years, 12, 13 and probably not for 10,000 years. Some 5,400 square miles (14,000 square kilometers) of ice have broken off from 10 floating Antarctic ice shelves. These include surface warming, which creates melt ponds that fracture the ice along existing crevasses 8 melting of the ice shelf from below, caused by warming ocean waters 9 and stresses that arise from the movement of ice, such as those that produce crevasses within the ice shelf. Scientists think that several mechanisms play a role in destabilizing ice shelves. In fact, rising temperatures in the region have contributed to the collapse of seven ice shelves in just the two decades before 2009. The warming of the Antarctic Peninsula has led to the progressive instability of its ice shelves. 2, 3 Expanded melting has dramatically changed the environment and ecology of the Antarctic Peninsula. 2, 3, 7 Warming has occurred at a faster pace during winter and autumn months on the west coast of the peninsula, raising the number of days with an average temperature above freezing each year by 74 percent. Over the past 50 years, average annual temperatures on the Antarctic Peninsula have risen at a rate of 0.9° F (0.5° C) per decade. Isolated snow-free areas on the peninsula in summertime provide breeding ground for marine mammals and birds, as well as habitat for primitive plants, microbes, and invertebrates. 2 Unlike other parts of Antarctica, it has a summer melting season. The Antarctic Peninsula is mountainous, with elevations generally exceeding 6,500 feet (2,000 meters). 5, 6 The Larsen B ice shelf was around 720 feet (220 meters) thick when it collapsed. 6 Instead, ice shelves, which are found along 45 percent of the Antarctic coast, are fed by glaciers, ice sheets, or local snowfall. Ice shelves are thick, floating sheets of ice attached to the coast that are not formed by freezing ocean water-unlike sea ice. The area lost was comparable in size to the U.S. 2, 3, 4 The Larsen B ice shelf drew the world's attention to the effects of global warming when it disintegrated into the ocean in 2002, sending a cascade of icebergs into the Weddell Sea. The Antarctic Peninsula has warmed considerably over the past five to six decades, at rates that far exceed the global average.

Antarctic ice shelf breaking off