New Maps Show How Greenland’s Ice Sheet Is Melting from the Bottom Up

New Maps Show How Greenland’s Ice Sheet Is Melting from the Bottom Up

SOURCE: Scientific American DATE: November 6, 2017 SNIP: Significantly more ice in Greenland’s glaciers may be exposed to warming ocean waters than previously thought, new research suggests. Indeed, more than half the ice sheet may be subject to the melting influence of the sea. These are the latest conclusions of a detailed mapping project exploring the topography of the seafloor and bedrock around and beneath Greenland’s glaciers. Published in their final form last week in the journal Geophysical Research Letters, the maps draw on a variety of data sources, including satellite radar and aerial imagery, as well as special sonar data collected on ship expeditions to the front of the ice sheet. Included in the new paper are some of the most detailed data yet on the depths of the canyons and fjords scarring the Greenland coast, which carry water in from the sea to lap against the ice. The results suggest that the western and northern regions of Greenland are most exposed to the influence of ocean water. Out of 139 ocean-touching glaciers the team identified, they also found that 67 rest in waters 200 meters (about 650 feet) or more below sea level, where warm water is typically found—at least twice as many as previously...
Pakistan’s glaciers face new threat: Highway’s black carbon

Pakistan’s glaciers face new threat: Highway’s black carbon

SOURCE: Reuters DATE: November 3, 2017 SNIP: The Karakoram Highway has been around since 1982, but the Chinese-funded upgrade – which opened in 2015 – has turned a once treacherous track into a 15-foot-wide paved road. A series of tunnels, cut through the mountains, have reduced the driving time to the Khunjerab Pass from Gilgit, the capital of Gilgit-Balistan region, from eight hours to four hours. Now trucks are pouring over the border, laden with Chinese goods and equipment headed to Sost, the first border town on the Pakistani side, and then further down the 1,300-kilometre (800-mile) highway toward the port of Gwadar. The highway upgrade, part of the ambitious China Pakistan Economic Corridor, “has two impacts – one is positive and the other negative,” said Qamar-uz-Zaman Chaudhry, the author of Pakistan’s national climate change policy. “It will bring in much-needed infrastructure. But the carbon emissions and the soot going into the atmosphere will definitely increase – and our mountain glaciers will melt. We need to do a comprehensive study on the impacts and then develop a strategy,” he said. [D]ata gathered over the last 50 years shows that all but around 120 of the glaciers are showing signs of melting, meteorological officials said. Warming temperatures are to blame for much of the melting but so-called “black carbon” – black soot released from diesel vehicle exhaust, factories, open fires and cookstoves – also is to blame, experts say. The highway upgrade is just part a huge Chinese investment push into infrastructure in Pakistan – including a series of new coal-fired power plants – under the China Pakistan Economic Corridor...
Intensifying Winds Could Increase East Antarctica’s Contribution to Sea Level Rise

Intensifying Winds Could Increase East Antarctica’s Contribution to Sea Level Rise

SOURCE: University of Texas News DATE: November 1, 2017 SNIP: Totten Glacier, the largest glacier in East Antarctica, is being melted from below by warm water that reaches the ice when winds over the ocean are strong—a cause for concern because the glacier holds more than 11 feet of sea level rise and acts as a plug that helps lock in the ice of the East Antarctic Ice Sheet. Research led by The University of Texas at Austin has found that wind is responsible for bringing warm water to Totten’s underbelly, causing the glacier to melt from below. This finding helps answer the question of what causes Totten to speed up some years and slow down in others. Climate change is expected to increase the intensity of winds over the Southern Ocean throughout the next century, and the new findings show that Totten Glacier will probably respond to the changing winds. During the next century, winds are expected to intensify and migrate closer to the East Antarctic coast as a result of increased atmospheric greenhouse gas. This study suggests that as winds over the Southern Ocean intensify, so will Totten Glacier’s contribution to global sea level...
New Greenland Maps Show More Glaciers at Risk

New Greenland Maps Show More Glaciers at Risk

SOURCE: NASA DATE: November 1, 2017 SNIP: New maps of Greenland’s coastal seafloor and bedrock beneath its massive ice sheet show that two to four times as many coastal glaciers are at risk of accelerated melting as previously thought. Researchers at the University of California at Irvine (UCI), NASA and 30 other institutions have published the most comprehensive, accurate and high-resolution relief maps ever made of Greenland’s bedrock and coastal seafloor. The new maps reveal that two to four times more oceanfront glaciers extend deeper than 600 feet (200 meters) below sea level than earlier maps showed. That’s bad news, because the top 600 feet of water around Greenland comes from the Arctic and is relatively cold. The water below it comes from farther south and is 6 to 8 degrees Fahrenheit (3 to 4 degrees Celsius) warmer than the water above. Deeper-seated glaciers are exposed to this warmer water, which melts them more rapidly. OMG Principal Investigator Josh Willis of JPL, who was not involved in producing the maps, said, “These results suggest that Greenland’s ice is more threatened by changing climate than we had...
Warm waters melting Antarctic ice shelves may have appeared for the first time in over 7,000 years

Warm waters melting Antarctic ice shelves may have appeared for the first time in over 7,000 years

SOURCE: The Conversation DATE: October 19, 2017 SNIP: The vast expanse of the Antarctic is a region of the world particularly vulnerable to climate change, where ice loss has the potential to significantly increase sea levels. Now, for possibly the first time in 7,000 years, a phenomenon known as “upwelling” (the upward flow of warmer ocean water to the surface), is thought to have caused recent ice shelf collapse around the continent – and the glacial thinning associated with it. The ocean surrounding Antarctica is extremely cold, but water over 300m deep, Circumpolar Deep Water (CDW), is about 3⁰C above the melting point of ice. Normally, the very cold water above keeps this away from ice shelves. But in some areas, CDW is spilling onto the shallow Antarctic continental shelf, causing the ice to thin. Ice shelf thinning has accelerated in recent decades, but the picture is not the same everywhere. While the east of the Antarctic has shown modest gains in ice thickness, the west has outstripped this with significant ice loss – up to 18% in vulnerable areas like the Amundsen and Bellingshausen...