14 January 2016, Science Daily, Study finds high melt rates on Antarctica’s most stable ice shelf. Melting rates found to be 25 times higher than expected. A new Scripps Institution of Oceanography at UC San Diego-led study measured a melt rate that is 25 times higher than expected on one part of the Ross Ice Shelf. The study suggests that high, localized melt rates such as this one on Antarctica’s largest and most stable ice shelf are normal and keep Antarctica’s ice sheets in balance. The Ross Ice Shelf, a floating body of land ice the size of France jutting out from the Antarctic mainland, continuously melts and grows in response to changes to both the ice sheet feeding it and the warmer Southern Ocean waters beneath it. For six weeks the researchers collected radar data to map changes in ice shelf thickness to understand the processes that contribute to melting at its base. The findings revealed dramatic changes in melt rate within less than a mile. The highest melting rates of more than 20 meters (66 feet) per year are thought to contribute to the rapid formation of channels at the base of the ice shelf, which can result from fresh water flowing out from lakes under the West Antarctica ice sheet. Shifts in subglacial drainage patterns change the location of these basal channels, which could impact the ice shelf’s stability by unevenly distributing the melting at the base. “The highest melt rates are all clustered at the start of a developing ice shelf channel,” said Scripps alumnus Oliver Marsh, a postdoctoral researcher at the University of Canterbury and lead author of the study. “The location of the melting strengthens the idea that freshwater from the local subglacial drainage system is responsible for the evolving ice shelf features.” Read more here
Tag Archives: Antarctica
9 January 2016, Climate News Network, Ice melt speeds up sea level rise. Scientists have found evidence suggesting that melting icecap water from the interior of Greenland is adding to sea level rise faster than previously realised. Water may be flowing from the Greenland icecapand into the sea more quickly than anybody expected. It doesn’t mean that global warming has got conspicuously worse: rather, researchers have had to revise their understanding of the intricate physiology of the northern hemisphere’s biggest icecap. There is enough ice and snow packed deep over 1.7 million square kilometres of Greenland that, were it all to melt, would cause a rise in global sea levels of about six metres. Climate calculations Since the icecap is melting as the atmospheric levels of the greenhouse gas carbon dioxide rise, and global temperatures rise with them, as a consequence of the human combustion of fossil fuels, the rate at which summer meltwater gets into the oceans becomes vital to climate calculations. The latest rethink begins not with the pools of water that collect on the surface each summer, or the acceleration of the glaciers as they make their way to the ocean, but with a granular layer of snow just below the surface, called firn. This is old snow in the process of being compacted into glacier ice, and covers the island in a layer up to 80 metres thick. Until now, researchers have understood this firn layer as a kind of sponge that absorbs meltwater and holds it, thus limiting the flow of melting ice into the sea. Read More here
29 December 2015, New York Times, Countries Rush for Upper Hand in Antarctica. On a glacier-filled island with fjords and elephant seals, Russia has built Antarctica’s first Orthodox church on a hill overlooking its research base, transporting the logs all the way from Siberia. Less than an hour away by snowmobile, Chinese laborers have updated the Great Wall Station, a linchpin in China’s plan to operate five bases on Antarctica, complete with an indoor badminton court, domes to protect satellite stations and sleeping quarters for 150 people. Not to be outdone, India’s futuristic new Bharathi base, built on stilts using 134 interlocking shipping containers, resembles a spaceship. Turkey and Iran have announced plans to build bases, too. More than a century has passed since explorers raced to plant their flags at the bottom of the world, and for decades to come this continent is supposed to be protected as a scientific preserve, shielded from intrusions like military activities and mining. But an array of countries are rushing to assert greater influence here, with an eye not just toward the day those protective treaties expire, but also for the strategic and commercial opportunities that exist right now. “The newer players are stepping into what they view as a treasure house of resources,” said Anne-Marie Brady, a scholar at New Zealand’s University of Canterbury who specializes in Antarctic politics. Read More here
18 November 2015, The Conversation, Shrinking Antarctic glaciers could make Adélie penguins unlikely winners of climate change. Penguin numbers exploded in East Antarctica at the end of the last ice age, according to research published today in BMC Evolutionary Biology. Despite their image as cold-loving creatures, the increase in Adélie penguin numbers seems to be closely linked to shrinking glaciers, raising the possibility the these penguins could be winners from current climate change. Adélie penguins are one of only two penguin species that live on the Antarctic continent. Their cousins, emperor penguins, may be the movie stars, but it is the Adélies that are the bigger players in the Southern Ocean. They outnumber emperors by more than ten to one, with a population of over 7.5 million breeding adults and counting. Given the abundance of Adélie penguins and their crucial role in Southern Ocean ecosystems, there has been a great deal of interest in understanding how the species is likely to respond to future climate change. Sensitivity to sea ice Breeding colonies have been monitored for decades to determine the effects of a changing environment on the penguins. A common finding of many of these studies is that Adélies are highly sensitive to sea ice conditions. Unlike emperor penguins, Adélies do not nest on the sea ice, but they must cross it to reach their nests on land. As everyone knows, penguins are not the most efficient walkers, and in years with a lot of sea ice their journeys to and from the ocean to feed their chicks can become lengthy. With a longer wait between meals chicks are less likely to survive. In an extreme case, extensive sea ice at one breeding colony had a devastating impact in 2014, and not a single chick survived. Read More here