Sea level rise quickens as Greenland ice sheet sheds record amount

Sea level rise quickens as Greenland ice sheet sheds record amount

SOURCE: Phys.org DATE: August 21, 2020 SNIP: Greenland’s massive ice sheet saw a record net loss of 532 billion tonnes last year, raising red flags about accelerating sea level rise, according to new findings. That is equivalent to an additional three million tonnes of water streaming into global oceans every day, or six Olympic pools every second. Crumbling glaciers and torrents of melt-water slicing through Greenland’s ice block—as thick as ten Eiffel Towers end-to-end—were the single biggest source of global sea level rise in 2019 and accounted for 40 percent of the total, researchers reported in the journal Communications Earth & Environment. Last year’s loss of mass was at least 15 percent above the previous record in 2012, but even more alarming are the long-term trends, they said. “2019 and the four other record-loss years have all occurred in the last decade,” lead author Ingo Sasgen, a glaciologist at the Helmholtze Centre for Polar and Marine Research in Germany, told AFP. The ice sheet is now tracking the worst-case global warming scenario of the UN’s climate science advisory panel, the IPCC, noted Andrew Shepherd, director of the Centre for Polar Observation and Modelling at the University of Leeds. “This means we need to prepare for an extra ten centimetres or so of global sea level rise by 2100 from Greenland alone,” said Shepherd, who was not involved in the study. Scientists not involved in the research were not surprised by the findings, but expressed concern. “The ice sheet has lost ice every year for the last 20 years,” said Twila Moon, a research scientists at the University of Colorado....
Warming Greenland ice sheet passes point of no return

Warming Greenland ice sheet passes point of no return

SOURCE: Phys.org DATE: August 13, 2020 SNIP: Nearly 40 years of satellite data from Greenland shows that glaciers on the island have shrunk so much that even if global warming were to stop today, the ice sheet would continue shrinking. The finding, published today, Aug. 13, in the journal Nature Communications Earth and Environment, means that Greenland’s glaciers have passed a tipping point of sorts, where the snowfall that replenishes the ice sheet each year cannot keep up with the ice that is flowing into the ocean from glaciers. “We’ve been looking at these remote sensing observations to study how ice discharge and accumulation have varied,” said Michalea King, lead author of the study and a researcher at The Ohio State University’s Byrd Polar and Climate Research Center. “And what we’ve found is that the ice that’s discharging into the ocean is far surpassing the snow that’s accumulating on the surface of the ice sheet.” The researchers found that, throughout the 1980s and 90s, snow gained through accumulation and ice melted or calved from glaciers were mostly in balance, keeping the ice sheet intact. Through those decades, the researchers found, the ice sheets generally lost about 450 gigatons (about 450 billion tons) of ice each year from flowing outlet glaciers, which was replaced with snowfall. The researchers’ analysis found that the baseline of that pulse—the amount of ice being lost each year—started increasing steadily around 2000, so that the glaciers were losing about 500 gigatons each year. Snowfall did not increase at the same time, and over the last decade, the rate of ice loss from glaciers has stayed...
Pools of Water Atop Sea Ice in the Arctic May Lead it to Melt Away Sooner Than Expected

Pools of Water Atop Sea Ice in the Arctic May Lead it to Melt Away Sooner Than Expected

SOURCE: Inside Climate News DATE: August 11, 2020 SNIP: The thickening atmospheric stew of greenhouse gases is punching holes in Arctic sea ice, leading it to crumble at a rapidly increasing rate. Last spring, ponds of meltwater on the ice sped the melting of the glossy shield that reflects incoming heat from the sun back to space. By July, the ice had dwindled to a record low extent for that month. It could disappear as soon as 2035, scientists said this week, as they released a study showing how the formation of melt ponds on the surface of the sea ice drove it to completely melt away about 130,000 years ago in an era called the Last Interglacial—probably the last time the Arctic Ocean was ice-free during summer. Observations show melt ponds forming earlier and persisting longer. Their blue water is darker than the white ice surrounding them, so they absorb more warmth from the sun. That heat seeps through the sides of the pond to melt more ice, and even oozes down to warm the ocean beneath it. Instead of a solid reflective mirror, the surface is increasingly pitted, scarred and cracked until, at its edges, it dissolves into the sea like an ice cube melting on a hot sidewalk. The imminent disappearance of Arctic sea ice has also raised concerns about the potential for international conflicts over the oil and gas deposits beneath the floors of Arctic seas, as well as over prized commercial fish stocks that have moved or are easier to reach due to the diminishing ice. The loss of sea ice buffers is probably...
Canada’s last fully intact Arctic ice shelf collapses

Canada’s last fully intact Arctic ice shelf collapses

SOURCE: Reuters DATE: August 6, 2020 SNIP: The last fully intact ice shelf in the Canadian Arctic has collapsed, losing more than 40% of its area in just two days at the end of July, researchers said on Thursday. The Milne Ice Shelf is at the fringe of Ellesmere Island, in the sparsely populated northern Canadian territory of Nunavut. “Above normal air temperatures, offshore winds and open water in front of the ice shelf are all part of the recipe for ice shelf break up,” the Canadian Ice Service said on Twitter when it announced the loss on Sunday. “Entire cities are that size. These are big pieces of ice,” said Luke Copland, a glaciologist at the University of Ottawa who was part of the research team studying the Milne Ice Shelf. The shelf’s area shrank by about 80 square kilometers. By comparison, the island of Manhattan in New York covers roughly 60 square kilometers. “This was the largest remaining intact ice shelf, and it’s disintegrated, basically,” Copland said. The Arctic has been warming at twice the global rate for the last 30 years, due to a process known as Arctic amplification. But this year, temperatures in the polar region have been intense. The polar sea ice hit its lowest extent for July in 40 years. Record heat and wildfires have scorched Siberian Russia. Summer in the Canadian Arctic this year in particular has been 5 degrees Celsius above the 30-year average, Copland said. That has threatened smaller ice caps, which can melt quickly because they do not have the bulk that larger glaciers have to stay cold. As...
Canadian ice caps disappear, confirming 2017 scientific prediction

Canadian ice caps disappear, confirming 2017 scientific prediction

SOURCE: Phys.org DATE: July 31, 2020 SNIP: The St. Patrick Bay ice caps on the Hazen Plateau of northeastern Ellesmere Island in Nunavut, Canada, have disappeared, according to NASA satellite imagery. National Snow and Ice Data Center (NSIDC) scientists and colleagues predicted via a 2017 paper in The Cryosphere that the ice caps would melt out completely within the next five years, and recent images from NASA’s Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) have confirmed that this prediction was accurate. Mark Serreze, director of NSIDC, Distinguished Professor of Geography at the University of Colorado Boulder, and lead author on the paper, first set foot on the St. Patrick Bay ice caps in 1982 as a young graduate student. He visited the ice caps with his advisor, Ray Bradley, of the University of Massachusetts. “When I first visited those ice caps, they seemed like such a permanent fixture of the landscape,” said Serreze. “To watch them die in less than 40 years just blows me away.” In 2017, scientists compared ASTER satellite data from July 2015 to vertical aerial photographs taken in August of 1959. They found that between 1959 and 2015, the ice caps had been reduced to only five percent of their former area, and shrank noticeably between 2014 and 2015 in response to the especially warm summer in 2015. The ice caps are absent from ASTER images taken on July 14,...