![]() ![]() That makes it especially vulnerable to the warming ocean. The ice sheet is draped over a series of islands, but most of it rests on the floor of a basin that dips more than 5,000 feet below sea level. Together they drain a much larger dome of ice called the West Antarctic Ice Sheet, which is up to two and a half miles thick and covers an area twice the size of Texas. The Pine Island Ice Shelf is the floating terminus of the Pine Island Glacier, one of several large glaciers that empty into the Amundsen Sea. See the Giant Crack in Larsen C Ice Shelf That Yielded Antarctica Iceberg ![]() But around the Amundsen Sea, a thousand miles to the southwest on the Pacific coast of Antarctica, the glaciers are far larger and the stakes far higher. That’s why a Delaware-size iceberg just broke off the Larsen C Ice Shelf and why smaller ice shelves on the peninsula have long since disintegrated entirely into the waters of the Weddell Sea. On the Antarctic Peninsula, the warming has been far greater-nearly five degrees on average. The water there has warmed by more than a degree Fahrenheit over the past few decades, and the rate at which ice is melting and calving has quadrupled. In 20 a 225-square-mile chunk of it broke off the end and drifted away on the Amundsen Sea. Its edges are shredded by rifts a quarter mile across. Its buckled surface is scarred by thousands of large crevasses. Seen from above, the Pine Island Ice Shelf is a slow-motion train wreck. It was first published on Jand updated on July 12 with news of the Larsen C break. It seems even in Antarctica we can identify human impacts on climate processes that are likely to have been operating for thousands of years.This story appears in the July 2017 issue of National Geographic magazine. Other studies have shown us that the way the SAM has changed over recent decades has an anthropogenic footprint. The researchers think this is due to large-scale changes in the way the wind circulates over Antarctica – the so-called Southern Annular Mode (SAM). Over the past 50 or so years the robust cycle of growth and decay in the Mertz glacier has broken down. David Stanley, CC BYĪs they drift away these huge icebergs create their own habitat cooling the seas and freshening the waters, and also seeding the oceans with iron which means more algae and plankton at the bottom of the food chain in remote locations such as South Georgia, where icebergs run aground and die. ![]() Chicks growing up near a massive iceberg may starve and die and some entire colonies may become unviable. When still close to shore these giant bergs are bad news for penguins, who suddenly have to travel much further – around the iceberg – to find open sea, and their food. It took two months for C28 to reach the deep water before it shattered into two pieces ( C28A and C28B since you ask) both still massive, and both went on to spawn further icebergs as they fractured into ever smaller pieces over the next few years. Very large icebergs get identifying codes this one became C28 as it was the 28th large iceberg from this sector of Antarctica. Given that the glacier is advancing about 1 km per year this means a super-iceberg tens of kilometres in length has regularly formed in this region.ī09B collides with the Mertz Glacier Tongue, causing it to break off and form a new iceberg. What they found is that every 70 or so years the Mertz polynya is absent for tens of years. Neal Young / Australian Antarctic Division It is quite an elegant way to investigate glacier flow.Ī massive iceberg (right) drifts slowly towards the Mertz tongue. If the sediment is dominated by species which live in the sea ice, then the polynya and the glacier tongue were absent. The proxies tell us which species of plankton dominated the region in a particular period: if the sediment is dominated by species which live in open water then they can infer that the polynya existed and so the Mertz Glacier had a long tongue extending north. What they did was take a core sample of sediment from the sea bed in the lee region (the red star in the above images) and look back in time using climate proxies such as the titanium content – which can be considered a proxy for the how much of the sediment comes from the land. The glacier tongue (blue) in summer and winter. This glacier forms one of these fingers of ice reaching out from the continent and the polynya in its lee can be up to 6,000 square kilometres. A new research article in the journal Nature Communications by a French team working in Antarctica has looked at the history of the polynya in the lee of the Mertz Glacier going back 250 years. ![]()
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