High Temperatures Set Off Major Greenland Ice Melt—Again

High Temperatures Set Off Major Greenland Ice Melt—Again

SOURCE: Scientific American DATE: June 3, 2020 SNIP: A significant melt event is unfolding in Greenland this week. With temperatures nearly 20 degrees Fahrenheit higher than usual in some areas, the southern part of the ice sheet is melting at its highest rate this season. Forecasts suggest that the melting on Greenland’s South Dome—one of the highest elevations on the ice sheet—may be the strongest for early June since 1950. It worries experts that Greenland could be priming for another big melt season. Early melting this spring, low snowpack in some areas and the potential for strong high-pressure weather systems later this summer have all raised red flags. Scientists are paying close attention after last summer’s record-breaking ice loss—an event scientists expect to occur more frequently as the Arctic continues to warm. Scientists typically define the beginning of melt season as the first three-day period in which melting is observed across at least 5% of the ice sheet. This year, that period began on May 13—nearly two weeks earlier on average over the last few decades. The melting coincided with a heat wave across much of the Arctic. Siberia and the central Arctic were some of the hardest-hit regions. But temperatures skyrocketed in parts of Greenland, as well, after an otherwise chilly start to the month. At the same time, snow began rapidly disappearing along the margins of the ice sheet, exposing bare rock and ice. The lack of snow is one factor increasing the possibility of an above-average melt year, according to Jason Box, an ice expert with the Geological Survey of Denmark and Greenland. It’s possible that...
Antarctic Ocean Reveals New Signs of Rapid Melt of Ancient Ice, Clues About Future Sea Level Rise

Antarctic Ocean Reveals New Signs of Rapid Melt of Ancient Ice, Clues About Future Sea Level Rise

SOURCE: Inside Climate News DATE: May 28, 2020 SNIP: Climate researchers racing to calculate how fast and how high the sea level will rise found new clues on the seafloor around Antarctica. A study released today suggests that some of the continent’s floating ice shelves can, during eras of rapid warming, melt back by six miles per year, far faster than any ice retreat observed by satellites. As global warming speeds up the Antarctic meltdown, the findings “set a new upper limit for what the worst-case might be,” said lead author Julian Dowdeswell, director of the Scott Polar Research Institute at the University of Cambridge. The estimate of ice shelf retreat is based on a pattern of ridges discovered on the seafloor near the Larsen Ice Shelf. The spacing and size of the ridges suggest they were created as the floating ice shelves rose and fell with the tides while rapidly shrinking back from the ocean. In findings published today in Science, the researchers estimate that to corrugate the seafloor in this way, the ice would have retreated by more than 150 feet per day for at least 90 days. Ice shelves float on the ocean but they are fastened to land and act as stoppers that prevent Antarctic ice sheets that are as big as the U.S. and Mexico combined from sliding into the sea. The shelves are frozen to outcrops on the seafloor, but when they melt away from those anchor points, the flow of ice into the ocean speeds up, accelerating sea level rise. If the rate of retreat estimated by the new study extended across...
Greenland ice sheet shrinks by record amount – climate study

Greenland ice sheet shrinks by record amount – climate study

SOURCE: Reuters DATE: April 15, 2020 SNIP: Greenland’s ice sheet shrank by more than at any time since record-taking began last year, according to a study published on Wednesday that showed the risk that climate change could cause sharp rises in global sea levels. The huge melt was due not only to warm temperatures, but also atmospheric circulation patterns that have become more frequent due to climate change, suggesting scientists may be underestimating the threat to the ice, the authors found. “We’re destroying ice in decades that was built over thousands of years,” Marco Tedesco, research professor at Columbia University’s Lamont-Doherty Earth Observatory, who led the study, told Reuters. “What we do here has huge implications for everywhere else in the world.” Greenland contributed 20-25% of global sea level rise over the last few decades, Tedesco said. If carbon emissions continue to grow, this share could rise to around 40% by 2100, he said, although there is considerable uncertainty about how ice melt will develop in Antarctica – the largest ice sheet on Earth. Most models used by scientists to project Greenland’s future ice loss do not capture the impact of changing atmospheric circulation patterns – meaning such models may be significantly underestimating future melting, the authors said. “It’s almost like missing half of the melting,” said...
Polar ice caps melting six times faster than in 1990s

Polar ice caps melting six times faster than in 1990s

SOURCE: The Guardian DATE: March 11, 2020 SNIP: The polar ice caps are melting six times faster than in the 1990s, according to the most complete analysis to date. The ice loss from Greenland and Antarctica is tracking the worst-case climate warming scenario set out by the Intergovernmental Panel on Climate Change (IPCC), scientists say. Without rapid cuts to carbon emissions the analysis indicates there could be a rise in sea levels that would leave 400 million people exposed to coastal flooding each year by the end of the century. Rising sea levels are the one of the most damaging long-term impacts of the climate crisis, and the contribution of Greenland and Antarctica is accelerating. The new analysis updates and combines recent studies of the ice masses and predicts that 2019 will prove to have been a record-breaking year when the most recent data is processed. The previous peak year for Greenland and Antarctic ice melting was 2010, after a natural climate cycle led to a run of very hot summers. But the Arctic heatwave of 2019 means it is nearly certain that more ice was lost last year. The average annual loss of ice from Greenland and Antarctica in the 2010s was 475bn tonnes – six times greater than the 81bn tonnes a year lost in the 1990s. In total the two ice caps lost 6.4tn tonnes of ice from 1992 to 2017, with melting in Greenland responsible for 60% of that figure. The IPCC’s most recent mid-range prediction for global sea level rise in 2100 is 53cm. But the new analysis suggests that if current trends continue...
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...