Greenlandâ€™s melting ice sheet is the worldâ€™s single biggest contributor to sea level rise. In a new study, scientists used drones to show how water flows through cracks in the ice, which creates dramatic waterfallsâ€”and could be making it more unstable.
After Greenland spent a good portion of July on fire, last weekâ€™s northern hemisphere heatwave similarly scorched the countryâ€™s ice sheet, triggering a meltdown affecting roughly 60 per cent of its surface. On Thursday alone, new data shows the ice shelf lost 12.5 billion tons to surface melting, its largest single-day loss in recorded history, the Washington Post reported.Read more
The report, published in the Proceedings of the National Academy of SciencesÂ on Monday, was the first one to ever use drones to observe how cracks form under meltwater lakes on Greenlandâ€™s ice shelf.
â€œTo date, most observations are provided by satellites,â€ said lead researcher Dr Poul Christoffersen. â€œThese allow us to see whatâ€™s happening over the whole ice sheet, but drone-based observations give a lot more nuance to our understanding of these lake drainages.â€
The team found that the cracks create caverns, or moulins, which the meltwater moves through. Since the ice sheet is about a kilometre (0.62 miles) thick, the flow of water into the moulins can create the worldâ€™s largest waterfalls.
In the summer of 2018, the UK researchers captured footage of a meltwater lake on the ice sheetâ€™s draining five million cubic meters of water from the ice sheetâ€™s surface in just five hours. Thatâ€™s enough water to fill 2,000 Olympic swimming pools.
The water flowed through a moulin to the base of the ice sheet, reducing the volume of the lake by two thirds. The quick flow of water from the lake also helped raise the surface of the ice by a little more than half a metre (1.8 feet). That could mean that the water flowed into hydrofractures, or spaces between the ice sheet and its base.
When water flows to an ice sheetâ€™s base, it â€œincreases the tensile stresses near other lakes, triggering further hydrofractures,â€ the scientists wrote. In other words, it can trigger a chain reaction, creating more cracks, loosening the bottom of the sheet and making it even more unstable. This can cause the glaciers to break off the ice sheetâ€”especially when itâ€™s draining fast.Â And the researchers say that the kind of fast drainage they observed may be happening much more often than scientists previously thought.
â€œItâ€™s possible weâ€™ve under-estimated the effects of these glaciers on the overall instability of the Greenland Ice Sheet,â€ the studyâ€™s co-lead author and drone pilot Tom Chudley said in a statement.
Earlier this year, scientists found that Greenlandâ€™s ice sheet it may have in one day.
As the Earth continues to warm, it will be increasingly important to see how the Greenland ice sheet will respond. In an attempt to understand its response, the researchers are now using drilling equipment to explore how climate change might affect the ice sheetâ€™s drainage systems. But last summerâ€™s disappear lake serves as quite a warning.
â€œItâ€™s a rare thing to actually observe these fast-draining lakesâ€”we were lucky to be in the right place at the right time,â€ said Chudley.
President Deals is up to it again! Over the past week, word got out that the White House has been exploring some kind of arrangement to buy the autonomous Danish territory of Greenland â€” which in addition to giving the U.S. more military access to a strategic point of the globe, would enable American exploitation of its vast mineral wealth, freshwater reserves, and... sand.Read more