29 November 2016, Carbon Brief, Guest post: Misleading media coverage of Antarctic sea ice paper. Dr Jonathan Day is a polar climate scientist at the University of Reading. His work focuses on understanding and predicting changes in sea ice in the Arctic and Antarctic. Last week, my colleague Tom Edinburgh and I published an article estimating the extent of Antarctic sea ice in the early 1900s, using sea ice observations recorded by explorers of the time. It received an overwhelming amount of coverage in the media. This was largely because it combined a human-interest story about the conditions faced by the early Antarctic explorers with an illuminating result regarding the thorny issue of Antarctic sea ice trends. Despite significant increases in global average temperature, sea ice in the Antarctic has been slightly increasing in extent over recent decades (1979 – present). Although much of the coverage was very well reported, there were other examples of the results being wrongfully interpreted, perhaps wilfully so. Some of the errors led to confusion, such as conflating sea ice with land ice. Others attempted to cast doubt on the link between greenhouse gases and global mean temperature, which was inappropriate and misleading. Read More here
Tag Archives: Antarctica
28 November 2016, Geophysical Research Letters (REPORT) Pine Island Glacier has undergone several major iceberg calving events over the past decades. These typically occurred when a rift at the heavily fractured shear margin propagated across the width of the ice shelf. This type of calving is common on polar ice shelves, with no clear connection to ocean-ice dynamic forcing. In contrast, we report on the recent development of multiple rifts initiating from basal crevasses in the center of the ice shelf, resulted in calving further upglacier than previously observed. Coincident with rift formation was the sudden disintegration of the ice mélange that filled the northern shear margin, resulting in ice sheet detachment from this margin. Examination of ice velocity suggests that this internal rifting resulted from the combination of a change in ice shelf stress regime caused by disintegration of the mélange and intensified melting within basal crevasses, both of which may be linked to ocean forcing. Read More here
27 October 2016, Aust Antarctic Division, Impact of East Antarctic glacial melt on sea-level rise. The Australian Antarctic Program will study two glaciers, the Totten and Sørsdal, in East Antarctica this summer to better understand the impact ice melt is having on global sea-level rise. The Totten Glacier, near Australia’s Casey research station, is the largest glacier in East Antarctica, and is showing signs that it is sensitive to warm ocean waters that can increase melt at the base of the ice shelf. Australian Antarctic Division Glaciologist, Dr Ben Galton-Fenzi, said researchers want to better understand how much this glacial melt is driving sea-level rise. “Since the 1900s the global sea-level has risen by around 20 centimetres and by the end of the century it’s projected to rise by up to one metre or more, but this is subject to high uncertainty,” Dr Galton Fenzi said. “These estimates depend critically on understanding Antarctic glaciers, both how much and how fast they melt in a warming climate. This summer researchers will look at how warmer ocean water is melting glaciers and ice shelves from below. “We will land helicopters on the Totten to deploy six GPS units to measure glacial flow speeds and surface elevation changes. Read More here
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