Greenland’s Growing “Ice Slabs” Intensify Meltwater Runoff into Ocean

Greenland’s Growing “Ice Slabs” Intensify Meltwater Runoff into Ocean

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...
Climate crisis: Greenland’s ice faces melting ‘death sentence’

Climate crisis: Greenland’s ice faces melting ‘death sentence’

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...
Greenland Is Melting Away Before Our Eyes

Greenland Is Melting Away Before Our Eyes

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...
Study Predicts More Long-Term Sea Level Rise from Greenland Ice

Study Predicts More Long-Term Sea Level Rise from Greenland Ice

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...
Rain may be causing a worrying amount of ice to melt in Greenland

Rain may be causing a worrying amount of ice to melt in Greenland

SOURCE: New Scientist DATE: March 7, 2019 DATE: Rain is becoming more common across Greenland’s ice sheet and it may be playing an important role in rising sea levels. Greenland’s 660,000-square mile ice sheet contains enough fresh water to flood coastal cities around the world. Warm air over the sheet is causing it to melt, but new work reveals that rainfall is also causing more melting than previously thought. An analysis of satellite and weather station records suggests that around 300 melt events in Greenland between 1979 and 2012 were linked to rainfall. Over this time, rain-associated melting became twice as frequent in summer, and three times as frequent in winter. Rain now appears to account for 28 per cent of the ice sheet’s melt. When precipitation falls as rain, it causes some of Greenland’s ice sheet to be covered in ice rather than snow. Come the summer, this ice reflects less of the sun’s energy, exacerbating summer melting. Historically, Greenland’s melt season has run between May and August, but rainfall means melting is now happening in winter too. “The rain events are extremely important because they are one of the only triggers for melting in winter,” says Marco Tedesco, of Columbia University in New York, who was involved in the...