Climate change: Greenland ice melt ‘is accelerating’

Climate change: Greenland ice melt ‘is accelerating’

SOURCE: BBC DATE: December 10, 2019 SNIP: Greenland is losing ice seven times faster than it was in the 1990s. The assessment comes from an international team of polar scientists who’ve reviewed all the satellite observations over a 26-year period. They say Greenland’s contribution to sea-level rise is currently tracking what had been regarded as a pessimistic projection of the future. It means an additional 7cm of ocean rise could now be expected by the end of the century from Greenland alone. This threatens to put many millions more people in low-lying coastal regions at risk of flooding. It’s estimated roughly a billion live today less than 10m above current high-tide lines, including 250 million below 1m. “Storms, if they happen against a baseline of higher seas – they will break flood defences,” said Prof Andy Shepherd, of Leeds University. “The simple formula is that around the planet, six million people are brought into a flooding situation for every centimetre of sea-level rise. So, when you hear about a centimetre rise, it does have impacts,” he told BBC News. Whereas in the early 90s, the rate of loss was equivalent to about 1mm per decade, it is now running at roughly 7mm per decade. Imbie team-member Dr Ruth Mottram is affiliated to the Danish Meteorological Institute. She said: “Greenland is losing ice in two main ways – one is by surface melting and that water runs off into the ocean; and the other is by the calving of icebergs and then melting where the ice is in contact with the ocean. The long-term contribution from these two processes is...
Greenland ice losses rising faster than expected

Greenland ice losses rising faster than expected

SOURCE: Phys.org DATE: December 10, 2019 SNIP: Greenland is losing ice seven times faster than in the 1990s and is tracking the Intergovernmental Panel on Climate Change’s high-end climate warming scenario, which would see 400 million more people exposed to coastal flooding by 2100. A team of 96 polar scientists from 50 international organisations have produced the most complete picture of Greenland ice loss to date. The Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) Team combined 26 separate surveys to compute changes in the mass of Greenland’s ice sheet between 1992 and 2018. Altogether, data from 11 different satellite missions were used, including measurements of the ice sheet’s changing volume, flow and gravity. The findings, published today in Nature today, show that Greenland has lost 3.8 trillion tonnes of ice since 1992—enough to push global sea levels up by 10.6 millimetres. The rate of ice loss has risen from 33 billion tonnes per year in the 1990s to 254 billion tonnes per year in the last decade—a seven-fold increase within three decades. The assessment, led by Professor Andrew Shepherd at the University of Leeds and Dr. Erik Ivins at NASA’s Jet Propulsion Laboratory in California, was supported by the European Space Agency (ESA) and the US National Aeronautics and Space Administration (NASA). Professor Shepherd said: “As a rule of thumb, for every centimetre rise in global sea level another six million people are exposed to coastal flooding around the planet.” “On current trends, Greenland ice melting will cause 100 million people to be flooded each year by the end of the century, so 400 million in total due to...
Ancient soil from secret Greenland base suggests Earth could lose a lot of ice

Ancient soil from secret Greenland base suggests Earth could lose a lot of ice

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...
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...
New Zealand glaciers won’t survive this century, scientists say

New Zealand glaciers won’t survive this century, scientists say

SOURCE: Stuff DATE: August 20, 2019 SNIP: Visitors to the Franz Josef glacier are noticing changes – it’s melting away and it’s not the only one. Victoria University of Wellington PHD Student Lauren Vargo said when surveys started in the late 1970s, New Zealand had more than 3000 glaciers. “From now on, we’ll see more disappear each year,” she said. “There are a couple that were quite decent sized glaciers when the surveys began, and they are essentially no longer glaciers and wouldn’t fit the definition of a glacier.” Most New Zealand glaciers have been rapidly declining since 2011. Both Franz Josef Glacier and Fox Glacier are no longer accessible by foot due to their retreat. Vargo said how long glaciers would survive climate change depended on their location and size. A recent and unpublished study has found New Zealand’s glacier areas reduced about 31 per cent from the late 1970s to 2016, Vargo said. This year it was found earth’s glaciers are melting much faster than scientists thought – five times faster now than they were in the 1960s. Niwa climate applications principal scientist Andrew Lorrey said if nothing changed globally, temperatures would continue to rise and the glaciers would continue to diminish. “Looking at these glaciers and how sensitive they are, I don’t see many of them surviving past the next century to be...