Eddie Gonzales Jr. – MessageToEagle.com – Researchers led by the University of Cambridge have used a drone – strong enough to withstand the extreme Arctic conditions – to observe how fractures form under meltwater lakes on the Greenland Ice Sheet.
The problem is these fractures cause the lakes to drain rapidly.
The observed fractures cause catastrophic lake drainages, in which huge quantities of surface water are transferred to the sensitive environment beneath the ice.
Each summer, thousands of lakes form on the Greenland Ice Sheet as the weather warms. Many of these lakes can drain in just a few hours, creating caverns (known as moulins), through which water descends to the bottom of the ice sheet.
“Given that the ice sheet is typically a kilometer thick or more, the flow of water into the moulins may well be the world’s largest waterfalls,” according to a press release.
In just five hours, five million cubic meters of water (1.3 billion gallows) – the equivalent of 2,000 Olympic-sized swimming pools – drained to the bottom of the ice sheet via the fracture, causing a new cavity to form and reducing the lake to a third of its original volume.
This caused the ice flow to accelerate from a speed of two meters per day to more than five meters per day as surface water was transferred to the bed, which in turn lifted the ice sheet by half a meter.
In multiple drone flights, the team was able to document the flow of water into the fracture and the water’s subsequent pathway under the ice.
“It’s possible we’ve under-estimated the effects of these glaciers on the overall instability of the Greenland Ice Sheet,” said first author Tom Chudley, a PhD student at the Scott Polar Research Institute and the team’s drone pilot.
“It’s a rare thing to actually observe these fast-draining lakes – we were lucky to be in the right place at the right time.”
Dr Poul Christoffersen, who led the expedition, said that “these glaciers are already moving quite fast, so the effect of the lakes may not appear to be as dramatic as it is on slower-moving glaciers elsewhere, but the overall effect is in fact very significant.”
“To date, most observations are provided by satellites.
The study, published in the Proceedings of the National Academy of Sciences.
Written by Eddie Gonzales Jr. – MessageToEagle.com Staff