by faster | Aug 21, 2020 | Blog
SOURCE: Phys.org DATE: August 21, 2020 SNIP: Greenland’s massive ice sheet saw a record net loss of 532 billion tonnes last year, raising red flags about accelerating sea level rise, according to new findings. That is equivalent to an additional three million tonnes of water streaming into global oceans every day, or six Olympic pools every second. Crumbling glaciers and torrents of melt-water slicing through Greenland’s ice block—as thick as ten Eiffel Towers end-to-end—were the single biggest source of global sea level rise in 2019 and accounted for 40 percent of the total, researchers reported in the journal Communications Earth & Environment. Last year’s loss of mass was at least 15 percent above the previous record in 2012, but even more alarming are the long-term trends, they said. “2019 and the four other record-loss years have all occurred in the last decade,” lead author Ingo Sasgen, a glaciologist at the Helmholtze Centre for Polar and Marine Research in Germany, told AFP. The ice sheet is now tracking the worst-case global warming scenario of the UN’s climate science advisory panel, the IPCC, noted Andrew Shepherd, director of the Centre for Polar Observation and Modelling at the University of Leeds. “This means we need to prepare for an extra ten centimetres or so of global sea level rise by 2100 from Greenland alone,” said Shepherd, who was not involved in the study. Scientists not involved in the research were not surprised by the findings, but expressed concern. “The ice sheet has lost ice every year for the last 20 years,” said Twila Moon, a research scientists at the University of Colorado....
by faster | Aug 13, 2020 | Blog
SOURCE: Phys.org DATE: August 13, 2020 SNIP: Nearly 40 years of satellite data from Greenland shows that glaciers on the island have shrunk so much that even if global warming were to stop today, the ice sheet would continue shrinking. The finding, published today, Aug. 13, in the journal Nature Communications Earth and Environment, means that Greenland’s glaciers have passed a tipping point of sorts, where the snowfall that replenishes the ice sheet each year cannot keep up with the ice that is flowing into the ocean from glaciers. “We’ve been looking at these remote sensing observations to study how ice discharge and accumulation have varied,” said Michalea King, lead author of the study and a researcher at The Ohio State University’s Byrd Polar and Climate Research Center. “And what we’ve found is that the ice that’s discharging into the ocean is far surpassing the snow that’s accumulating on the surface of the ice sheet.” The researchers found that, throughout the 1980s and 90s, snow gained through accumulation and ice melted or calved from glaciers were mostly in balance, keeping the ice sheet intact. Through those decades, the researchers found, the ice sheets generally lost about 450 gigatons (about 450 billion tons) of ice each year from flowing outlet glaciers, which was replaced with snowfall. The researchers’ analysis found that the baseline of that pulse—the amount of ice being lost each year—started increasing steadily around 2000, so that the glaciers were losing about 500 gigatons each year. Snowfall did not increase at the same time, and over the last decade, the rate of ice loss from glaciers has stayed...
by faster | Jun 3, 2020 | Blog
SOURCE: Scientific American DATE: June 3, 2020 SNIP: A significant melt event is unfolding in Greenland this week. With temperatures nearly 20 degrees Fahrenheit higher than usual in some areas, the southern part of the ice sheet is melting at its highest rate this season. Forecasts suggest that the melting on Greenland’s South Dome—one of the highest elevations on the ice sheet—may be the strongest for early June since 1950. It worries experts that Greenland could be priming for another big melt season. Early melting this spring, low snowpack in some areas and the potential for strong high-pressure weather systems later this summer have all raised red flags. Scientists are paying close attention after last summer’s record-breaking ice loss—an event scientists expect to occur more frequently as the Arctic continues to warm. Scientists typically define the beginning of melt season as the first three-day period in which melting is observed across at least 5% of the ice sheet. This year, that period began on May 13—nearly two weeks earlier on average over the last few decades. The melting coincided with a heat wave across much of the Arctic. Siberia and the central Arctic were some of the hardest-hit regions. But temperatures skyrocketed in parts of Greenland, as well, after an otherwise chilly start to the month. At the same time, snow began rapidly disappearing along the margins of the ice sheet, exposing bare rock and ice. The lack of snow is one factor increasing the possibility of an above-average melt year, according to Jason Box, an ice expert with the Geological Survey of Denmark and Greenland. It’s possible that...
by faster | Apr 15, 2020 | Blog
SOURCE: Reuters DATE: April 15, 2020 SNIP: Greenland’s ice sheet shrank by more than at any time since record-taking began last year, according to a study published on Wednesday that showed the risk that climate change could cause sharp rises in global sea levels. The huge melt was due not only to warm temperatures, but also atmospheric circulation patterns that have become more frequent due to climate change, suggesting scientists may be underestimating the threat to the ice, the authors found. “We’re destroying ice in decades that was built over thousands of years,” Marco Tedesco, research professor at Columbia University’s Lamont-Doherty Earth Observatory, who led the study, told Reuters. “What we do here has huge implications for everywhere else in the world.” Greenland contributed 20-25% of global sea level rise over the last few decades, Tedesco said. If carbon emissions continue to grow, this share could rise to around 40% by 2100, he said, although there is considerable uncertainty about how ice melt will develop in Antarctica – the largest ice sheet on Earth. Most models used by scientists to project Greenland’s future ice loss do not capture the impact of changing atmospheric circulation patterns – meaning such models may be significantly underestimating future melting, the authors said. “It’s almost like missing half of the melting,” said...
by faster | Oct 29, 2019 | Blog
SOURCE: Science DATE: October 29, 2019 SNIP: In one of the Cold War’s oddest experiments, the United States dug a 300-meter-long military base called Camp Century into the ice of northwest Greenland in the early 1960s, powered it with a nuclear reactor, and set out to test the feasibility of shuttling nuclear missiles beneath the ice. A constant struggle against intruding snow doomed the base, which was abandoned in 1966. But Camp Century has left a lasting, entirely nonmilitary legacy: a 1.3-kilometer-long ice core drilled at the site. The core, extracted by a team that included glaciologist Chester Langway, yielded a record of past temperatures that helped kick off studies of Earth’s ancient climate. And last week, dozens of scientists met here at the University of Vermont (UVM) to take stock of another gift from the core: mud from Greenland’s ancient land surface, serendipitously discovered in archived samples. New analyses of the mud suggest Greenland’s massive ice sheet was largely absent in a warm period during the past million years when the global climate was much like today’s. The samples likely have more stories to tell, UVM geophysicist Paul Bierman said at the gathering, which he organized to discuss recent results and plan further analyses. Drew Christ, a geochemist in the lab who prepared the samples, sent thawed samples to the lab of Eric Steig, a glaciologist at the University of Washington in Seattle, who measured ratios of oxygen isotopes to tease out past temperature. He also sent pieces of frozen muck to Tammy Rittenour, a geologist at Utah State University in Logan who specializes in luminescence dating: blasting...
