British Antarctic research station to shut for second winter as cracks in ice grow

British Antarctic research station to shut for second winter as cracks in ice grow

SOURCE: The Guardian DATE: October 31, 2017 SNIP: A British research station in Antarctica is being shut down for the second winter in a row following concerns over growing cracks in the 150-metre thick ice shelf on which it stands. The Halley VI station, which is parked on the Brunt ice shelf, will be shut down between March and November 2018, with the 14-strong staff who had been gearing up for the winter stint redeployed elsewhere in Antarctica or brought home to the UK. The worries are based on two cracks. The first is an ice chasm that began to show movement northwards in 2012, after more than 30 years of dormancy, and has accelerated over the past seven months. The second, north of the research station, has been dubbed the “Halloween crack” after it appeared in October 2016. It is now estimated to be about 50km in length and growing eastwards, crossing a resupply route for the station. “It has grown a couple of kilometres during the winter period,” said Professor David Vaughan, director of science at the British Antarctic Survey, adding that the crack had also...
Worrying new research finds that the ocean is cutting through a key Antarctic ice shelf

Worrying new research finds that the ocean is cutting through a key Antarctic ice shelf

SOURCE: Washington Post DATE: October 11, 2017 SNIP: A new scientific study published Tuesday has found that warm ocean water is carving an enormous channel into the underside of one of the key floating ice shelves of West Antarctica, the most vulnerable sector of the enormous ice continent. The Dotson ice shelf, which holds back two separate large glaciers, is about 1,350 square miles in area and between 1,000 and 1,600 feet thick. But on its western side, it is now only about half that thickness, said Noel Gourmelen, a researcher at the University of Edinburgh in Scotland and the lead author of the research, which was just published in Geophysical Research Letters. The reason is the same one that is believed to be shrinking glaciers and pouring ice into the ocean across West Antarctica — warm ocean water located offshore is now reaching the ice from below. “We think that this channel is actually being carved for the last 25 years,” said Gourmelen, whose research team detected the channel using satellite observations. “It’s been thinning and melting at the base for at least 25 years, and that’s where we are now.” Dotson ice shelf as a whole has been thinning at an average rate of more than eight feet per year since 1994, even as the speed of ice flowing outward through the shelf has increased by 180 percent. But the thinning in the channel has been far greater. The research calculates that 45 feet of ice thickness is being subtracted annually from the channel. The new study calculates that as a result of this highly uneven melting,...
Scientists mapping Greenland have produced some surprising – and worrying – results

Scientists mapping Greenland have produced some surprising – and worrying – results

SOURCE: Washington Post DATE: October 4, 2017 SNIP: Two new studies of Greenland, using sophisticated technologies and large scientific teams to pull together and process the data, have now gone further in taking the full measure of the island through that ever-so-basic scientific act: mapping. The first, a comprehensive seabed mapping project, relying in part on new data from NASA’s OMG (“Oceans Melting Greenland”) mission, concludes that the Greenland ice sheet is far more exposed to the planet’s warming oceans than previously known — and has more ice to give up than, until now, has been recognized. The new research finds that “between 30 and 100% more glaciers are potentially exposed to [warm Atlantic water] than suggested by previous mapping, which represents 55% of the ice sheet’s total drainage area.” In other words, more than half of Greenland’s ice lies in or flows through areas that could be influenced by warming seas. Meanwhile, on Wednesday, a separate team of scientists used another quite different large-scale mapping exercise to document a surprising — but closely related — change in Greenland’s above-water topography. Publishing in the journal Nature, they showed that the contours of the huge island are changing because with all the ice melt rushing from glaciers to the sea, river deltas are expanding outward — a rare occurrence these days when deltas around the world are generally retreating, threatened by rising seas (think of the Mississippi River delta, for instance, and its vanishing wetlands). “Over the period of the 1980s to 2010s, rapid increase of meltwater and sediment fluxes caused dramatic advance of these deltas into the ocean,” said...
As ice thaws, rock avalanches on Southeast Alaska mountains are getting bigger

As ice thaws, rock avalanches on Southeast Alaska mountains are getting bigger

SOURCE: Alaska Dispatch News DATE: September 19, 2017 SNIP: A study of rock avalanches in the western part of Glacier Bay National Park and Preserve found that the likelihood of large slides covering about 2 square miles has at least doubled in the last five years. As the climate has warmed, characteristics of the region’s rock avalanches have changed, says the study, published in Landslides, the journal of the International Consortium on Landslides. “They’re bigger, and they’re traveling farther,” said lead author Jeffrey Coe, a U.S. Geological Survey landslide expert based in Colorado. The likely reason, says the study, is thaw of the ice that fills the mountains’ rock cracks, crevices and fractures, referred to as “rock-permafrost,” abetted by melt of the region’s glaciers and the particular structures of the slopes. The rock-permafrost helps hold steep slopes intact, so thaw or even softening of that ice destabilizes the rock, Coe said. “You can get ice degradation below freezing,” he said. Glacial thinning is likely a secondary factor, he said. Thinned glaciers are less effective at propping up mountain faces, he said. “In many places, you have a de-buttressing effect of the ice loss,” he said. The study correlates the increasing size of Glacier Bay rock avalanches to a long-term warming trend. The large avalanches began about two years after the area’s annual maximum temperature shifted above freezing, the study points...
Sunnier Skies Driving Greenland Surface Melt

Sunnier Skies Driving Greenland Surface Melt

SOURCE: Climate Central DATE: June 28, 2017 SNIP: In the past two decades, the Greenland ice sheet has become the biggest single contributor to rising sea levels, mostly from melt across its vast surface. That surface melt is, in turn, driven mostly by an uptick in clear, sunny summer skies, not just rising air temperatures, a new study finds. While some of the water Greenland is flushing out to sea comes from warming ocean waters lapping away at the glaciers that drain the ice sheet, most is due to the melt across its surface during the summer. Stefan Hofer, a PhD candidate at the University of Bristol in England, and his colleagues looked into what the main drivers of that surface melt were, in particular the effect of cloud cover on melt. In satellite data spanning the past two decades, they saw a significant decrease in cloud cover over Greenland starting in the mid-90s, which would mean more sunlight was falling on the ice and driving melt. Climate models the team used suggest that every 1 percent reduction in cloud cover leads to another 27 gigatons of melt (the U.S. uses about 1.3 gigatons of water per day, according to data from NASA and the U.S. Geological Survey). That sensitivity to cloud cover was “pretty astounding,” William Colgan, a senior researcher with the Geological Survey of Denmark and Greenland who wasn’t involved in the study, said in an...