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...
by faster | Jul 31, 2019 | Blog
SOURCE: Rolling Stone DATE: July 31, 2019 SNIP: Amid an ongoing heat wave, new data show the Greenland ice sheet is in the middle of its biggest melt season in recorded history. It’s the latest worrying signal climate change is accelerating far beyond the worst fears of even climate scientists. The record-setting heat wave that sweltered northern Europe last week has moved north over the critically vulnerable Greenland ice sheet, triggering temperatures this week that are as much as 25 to 30 degrees Fahrenheit warmer than normal. Weather models indicate Tuesday’s temperature may have surpassed 75 degrees Fahrenheit in some regions of Greenland, and a weather balloon launched near the capital Nuuk measured all-time record warmth just above the surface. That heat wave is still intensifying, and is expected to peak on Thursday with the biggest single-day melt ever recorded in Greenland. On August 1 alone, more than 12 billion tons of water will permanently melt away from the ice sheet and find its way down to the ocean, irreversibly raising sea levels globally. A tweet from the Danish Meteorological Institute, the official weather service of Greenland, said “almost all the ice sheet, including Summit” measurably melted on Tuesday. According to a preliminary estimate, that melt covered 87 percent of the ice sheet’s surface, which would be the second-biggest melt day in Greenland’s recorded history. Separate weather monitoring equipment at Summit Camp at the top of the 10,000-foot-thick Greenland ice sheet confirmed the temperature briefly reached the melting point. This week alone, Greenland will lose about 50 billion tons of ice, enough for a permanent rise in global sea...
by faster | Jun 19, 2019 | Blog
SOURCE: NASA DATE: June 19, 2019 SNIP: In the next 200 years, the ice sheet model shows that melting at the present rate could contribute 19 to 63 inches to global sea level rise, said the team led by scientists at the Geophysical Institute at the University of Alaska Fairbanks. These numbers are at least 80 percent higher than previous estimates, which forecasted up to 35 inches of sea level rise from Greenland’s ice. The team ran the model 500 times out to the year 3000 for each of three possible future climate scenarios, adjusting key land, ice, ocean and atmospheric variables to test their effects on ice melt rate. The three climate scenarios depend on the amount of greenhouse gas emissions in the atmosphere in coming years. In the scenario with no reduction of emissions, the study found that the entire Greenland Ice Sheet will likely melt in a millennium, causing 17 to 23 feet of sea level rise. Capturing the changing flow and speed of outlet glacier melt makes the updated ice sheet model more accurate than previous models, according to the authors. As ocean waters have warmed over the past 20 years, they have melted the floating ice that shielded the outlet glaciers from their rising temperatures. As a result, the outlet glaciers flow faster, melt and get thinner, with the lowering surface of the ice sheet exposing new ice to warm air and melting as well. Each of the three emissions scenarios used in the study produced different patterns of ice retreat across Greenland. The least severe scenario showed the ice retreating in the west...
