24 October 2016, NASA, Studies offer new glimpse of melting under Antarctic glaciers. Two new studies by researchers at NASA and the University of California, Irvine (UCI), detect the fastest ongoing rates of glacier retreat ever observed in West Antarctica and offer an unprecedented direct view of intense ice melting from the floating undersides of glaciers. The results highlight how the interaction between ocean conditions and the bedrock beneath a glacier can influence the glacier’s evolution, with implications for understanding future ice loss from Antarctica and global sea level rise. The two studies examined three neighboring glaciers in West Antarctica that are melting and retreating at different rates. Smith, Pope and Kohler glaciers flow into the Dotson and Crosson ice shelves in the Amundsen Sea Embayment in West Antarctica, the part of the continent with the largest loss of ice mass. A study led by Bernd Scheuchl of UCI, published in the journal Geophysical Research Letters on Aug. 28, used radar measurements from the European Space Agency’s Sentinel-1 satellite and data from the earlier ERS-1 and ERS-2 satellites to look at changes in the glaciers’ grounding lines — the boundary where a glacier loses contact with bedrock and begins to float on the ocean. The grounding line is important because nearly all glacier melting takes place on the underside of the glacier’s floating portion, called the ice shelf. If a glacier loses mass from enhanced melting, it may start floating farther inland from its former grounding line, just as a boat stuck on a sandbar may be able to float again if a heavy cargo is removed. This is called grounding line retreat. Read More here
Category Archives: Antarctica
20 October 2016, Climate Home, Antarctic ice shelf collapse pits fishing against science. The UK is calling for a ten-year fishing moratorium in seas vacated by Antarctica’s collapsing ice shelves. The proposal, which was shared with Climate Home, passed the scientific committee of the UN Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) on Thursday. Russia has the power to veto the move when it goes to a full commission debate in Tasmania next week, however, and has consistently opposed territorial limits to fishing vessels in the far south. The collapse of an ice shelf provides a one-of-a-kind scientific laboratory, said Phil Trathan, a scientist at the British Antarctic Survey and one of the authors of the proposal. The newly open waters provide a window into the hidden processes of ocean ecosystems. “All of these areas are covered by ice and when that goes then there’ll be a whole new community develop under there. And given that a lot of communities develop quite slowly in the Antarctic then we can look at how they develop through time,” said Trathan speaking from Hobart, where the CCAMLR meeting is taking place. “If fisheries are going to exploit those areas before we have a chance to look at them scientifically then it’s a lost opportunity.” Antartica’s great ice shelves project out over the ocean from the fringes of the land. They are in a state of rapid decline, losing a total of 310 cubic km of ice every year. Once a shelf becomes too thin to support its own weight, it collapses in dramatic style, as was witnessed by satellites when the 3,250 sq km Larsen B ice shelf disintegrated within a few months at the beginning of 2002. Read more here
29 September 2016, The Conversation, Record high to record low: what on earth is happening to Antarctica’s sea ice? 2016 continues to be a momentous year for Australia’s climate, on track to be the new hottest year on record. To our south, Antarctica has also just broken a new climate record, with record low winter sea ice. After a peak of 18.5 million square kilometres in late August, sea ice began retreating about a month ahead of schedule and has been setting daily low records through most of September. It may not seem unusual in a warming world to hear that Antarctica’s sea ice – the ice that forms each winter as the surface layer of the ocean freezes – is reducing. But this year’s record low comes hot on the heels of record high sea ice just two years ago. Overall, Antarctica’s sea ice has been growing, not shrinking. So how should we interpret this apparent backflip? In our paper published today in Nature Climate Change we review the latest science on Antarctica’s climate, and why it seems so confusing. Antarctic surprises. First up, Antarctic climate records are seriously short. The International Geophysical Year in 1957/58 marked the start of many sustained scientific efforts in Antarctica, including regular weather readings at research bases. These bases are mostly found on the more accessible parts of Antarctica’s coast, and so the network – while incredibly valuable – leaves vast areas of the continent and surrounding oceans without any data. In the end, it took the arrival of satellite monitoring in the 1979 to deliver surface climate information covering all of Antarctica and the Southern Ocean. What scientists have observed since has been surprising. Read More here
19 September 2016, The Conversation, Disruption over Macquarie Island calls for some clever Antarctic thinking. The fate of the Australian Antarctic Division’s research base on Macquarie Island hangs in the balance, after last week’s surprise announcement that it would close in March 2017 was followed on Friday by a suggestion that the government could yet reprieve it. Why all the fuss over a scattering of buildings on a windswept island (admittedly a UNESCO World Heritage-listed one) perched on a tectonic ridge halfway between Australia and Antarctica? Macquarie Island is the perfect natural laboratory for scientific research. Unique climate, geological, biological and astronomical measurements are collected year-round. The data is fed into many large-scale, international science programs and reports, including those published by the Intergovernmental Panel on Climate Change. It is something of an anomaly in Australia’s national Antarctic program. Unlike Heard Island, Macquarie Island lies outside the areas covered by the Antarctic Treaty and the Convention on the Conservation of Antarctic Marine Living Resources. The Tasmanian government manages the island. The buildings at the island’s north end are home to research infrastructure and accommodation for various organisations. These include the Tasmanian Parks and Wildlife Service, the Bureau of Meteorology, and the Australian Radiation Protection and Nuclear Safety Agency, which monitors the Southern Ocean for evidence of nuclear events. These buildings are increasingly exposed to ocean inundation. Read More here