Scientists Find Record Warm Water in Antarctica, Pointing to Cause Behind Troubling Glacier Melt

Scientists Find Record Warm Water in Antarctica, Pointing to Cause Behind Troubling Glacier Melt

SOURCE: NYU DATE: January 29,2020 SNIP: A team of scientists has observed, for the first time, the presence of warm water at a vital point underneath a glacier in Antarctica—an alarming discovery that points to the cause behind the gradual melting of this ice shelf while also raising concerns about sea-level rise around the globe. The recorded warm waters—more than two degrees above freezing—flow beneath the Thwaites Glacier, which is part of the Western Antarctic Ice Sheet. The discovery was made at the glacier’s grounding zone—the place at which the ice transitions between resting fully on bedrock and floating on the ocean as an ice shelf and which is key to the overall rate of retreat of a glacier. Thwaites’ demise alone could have significant impact globally. It would drain a mass of water that is roughly the size of Great Britain or the state of Florida and currently accounts for approximately 4 percent of global sea-level rise. Some scientists see Thwaites as the most vulnerable and most significant glacier in the world in terms of future global sea-level rise—its collapse would raise global sea levels by nearly one meter, perhaps overwhelming existing populated areas. While the glacier’s recession has been observed over the past decade, the causes behind this change had previously not been determined. The scientists’ measurements were made in early January, after the research team created a 600-meter deep and 35-centimeter wide access hole and deployed an ocean-sensing device to measure the waters moving below the glacier’s surface. This device gauges the turbulence of the water as well as other properties such as temperature. The result...
Scientists find far higher than expected rate of underwater glacial melting

Scientists find far higher than expected rate of underwater glacial melting

SOURCE: Phys.org DATE: January 29, 2020 SNIP: Tidewater glaciers, the massive rivers of ice that end in the ocean, may be melting underwater much faster than previously thought, according to a Rutgers co-authored study that used robotic kayaks. The findings, which challenge current frameworks for analyzing ocean-glacier interactions, have implications for the rest of the world’s tidewater glaciers, whose rapid retreat is contributing to sea-level rise. The study, published in the journal Geophysical Research Letters, surveyed the ocean in front of 20-mile-long LeConte Glacier in Alaska. The seaborne robots made it possible for the first time to analyze plumes of meltwater, the water released when snow or ice melts, where glaciers meet the ocean. It is a dangerous area for ships because of ice calving—when falling slabs of ice that break from glaciers crash into the water and spawn huge waves. “With the kayaks, we found a surprising signal of melting: Layers of concentrated meltwater intruding into the ocean that reveal the critical importance of a process typically neglected when modeling or estimating melt rates,” said lead author Rebecca Jackson, a physical oceanographer and assistant professor in the Department of Marine and Coastal Sciences in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick. Two kinds of underwater melting occur near glaciers. Where freshwater discharge drains at the base of a glacier (from upstream melt on the glacier’s surface), vigorous plumes result in discharge-driven melting. Away from these discharge outlets, the glacier melts directly into the ocean waters in a regime called ambient melting. The study follows one published last year in the journal Science that measured...
New Zealand glaciers turn brown from Australian bushfires’ smoke, ash and dust

New Zealand glaciers turn brown from Australian bushfires’ smoke, ash and dust

SOURCE: The Guardian DATE: January 1, 2020 SNIP: Snow and glaciers in New Zealand have turned brown after being exposed to dust from the Australian bushfires, with one expert saying the incident could increase glacier melt this season by as much as 30%. On Wednesday many parts of the South Island woke up to an orange haze and red sun, after smoke from the Victorian and New South Wales blazes drifted east on Tuesday night, smothering many parts of the island for most of the day. On Thursday, pictures taken from the Southern Alps showed the smoke haze carrying particles of dust had tinged snow-capped mountain peaks and glaciers a shade of caramel, with former prime minister Helen Clark expressing concern for the long-lasting environmental impacts on the mountains. “Impact of ash on glaciers is likely to accelerate melting,” Clark tweeted. “How one country’s tragedy has spillover effects.” There are more than 3,000 glaciers in New Zealand and since the 1970s scientists have recorded them shrinking by nearly a third, with current estimates predicting they will disappear entirely by the end of the century. Professor Andrew Mackintosh is head of the school of earth, atmosphere and environment at Monash University, and the former director of the Antarctic Research Centre. He said in nearly two decades of studying glaciers in New Zealand he had never seen such a quantity of dust transported across the Tasman, and the current event had the potential to increase this season’s glacier melt by 20-30%, although Mackintosh stressed this was no more than an estimate. Mackintosh said the whiteness of snow and ice reflected the...
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...
Mighty glacier finally succumbs to climate change

Mighty glacier finally succumbs to climate change

SOURCE: The Sydney Morning Herald DATE: November 8, 2019 SNIP: One of the world’s thickest mountain glaciers is finally succumbing to global warming, a new analysis reports. The Taku Glacier, located north of Juneau, Alaska, has started to retreat as temperatures rise, said Mauri Pelto, a glaciologist at Nichols College in Massachusetts. Up until now, of the 250 glaciers that he has studied, all had retreated except one: Taku Glacier. But an analysis shows that Taku has lost mass and joined the rest of the retreating glaciers. “This is a big deal for me because I had this one glacier I could hold on to,” Pelto told NASA’s Earth Observatory. “But not anymore. This makes the score climate change: 250, and alpine glaciers: 0.” New photos released by NASA this week show that the melting of Taku has at last become visible. Taku is an extremely thick glacier: in fact, it is one of the thickest known alpine glaciers in the world, measuring nearly 1500 metres from surface to bed. A study about the glacier’s retreat was published last month in the journal Remote Sensing. Overall, thanks to global warming, Earth’s glaciers continue to melt away, losing up to 390 billion tonnes of ice and snow per year, a study published earlier this year suggests. The largest losses were glaciers in Alaska, followed by the melting ice fields in southern South America and glaciers in the Arctic. At 3885 square kilometres, the Juneau ice field is a third larger than the US state of Rhode Island, stretching from the Pacific Ocean into Canada, according to the Anchorage Daily News....