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...
by faster | Sep 18, 2019 | Blog
SOURCE: CIRES DATE: September 18, 2019 SNIP: Thick, impenetrable ice slabs are expanding rapidly on the interior of Greenland’s ice sheet, where the ice is normally porous and able to reabsorb meltwater. These slabs are instead sending meltwater spilling into the ocean, according to a new CIRES-led assessment, threatening to increase the country’s contribution to sea level rise by as much as 2.9 inches by 2100. Although runoff from ice slabs has added less than a millimeter to global sea levels so far, this contribution will grow substantially as ice slabs continue to expand in a warming climate, said Mike MacFerrin, a CIRES and University of Colorado Boulder researcher who led the new study, published today in Nature. “Even under moderate climate projections, ice slabs could double the size of the runoff zone by 2100,” MacFerrin said. “Under higher emissions scenarios, the runoff zone nearly triples in size.” “As the climate continues to warm, these ice slabs will continue to grow and enhance other meltwater feedbacks,” said Mahsa Moussavi, NSIDC researcher and a coauthor on the paper. “It’s a snowball effect: more melting creates more ice slabs, which create more melting, which, creates again more ice slabs.” This process fundamentally alters the ice sheet’s present and future hydrology. Arctic feedbacks like this are critical to understand because they show just how much, and how quickly, a warming climate can change Earth’s most vulnerable...
by faster | Sep 3, 2019 | Blog
SOURCE: BBC DATE: September 3, 2019 SNIP: Greenland’s massive ice sheet may have melted by a record amount this year, scientists have warned. During this year alone, it lost enough ice to raise the average global sea level by more than a millimetre. Researchers say they’re “astounded” by the acceleration in melting and fear for the future of cities on coasts around the world. One glacier in southern Greenland has thinned by as much as 100 metres since I last filmed on it back in 2004. Another revelation is that the ice is not only being melted by the air, as the atmosphere heats up, but also by warmer water reaching underneath the fronts of the glaciers. One Nasa scientist describes the ice as being under a hair-dryer and at the same time also on a cooker. One of the scientists studying the ice sheet, Dr Jason Box of the Geological Survey of Denmark and Greenland (GEUS), says he’s unnerved by the potential dangers and that coastal planners need to “brace themselves”. “Now that I’m starting to understand more of the consequences, it’s actually keeping me awake at night because I realise the significance of this place around the world and the livelihoods that are already affected by sea level rise,” he told me. According to Dr Box, it’s the recent increase in the average temperature that’s being felt in Greenland’s ice: “Already effectively that’s a death sentence for the Greenland ice sheet because also going forward in time we’re expecting temperatures only to climb,” he said. “So, we’re losing Greenland – it’s really a question of how...
