Much has been made recently of the possibility that the Greenland ice-sheet could doom us all. Al Gore unwisely used it in his movie An Inconvenient Truth, without providing any references, saying that if the ice-sheet melted, it would raise sea-levels 6.5 meters. Of course, this is entirely true – Greenland’s ice-sheet could do this – it’s just not going to anytime soon.
And according to recent research, even the more dire warnings of recent times aren’t to be believed either.
Of late, the view that Greenland’s ice-sheet was sliding in to the ocean off its coast was worrying many. Melt water atop the glaciers was forming, creating giant pools of warmer water which would, eventually, bore down through the ice creating what is known as moulins. Thus, the melt water would begin pooling underneath the glacier, and increase the slippery-slide effect towards the ocean.
Many thought that such events would see a positive feedback loop, whereby the acceleration of the ice towards the warmer weather towards sea level would increase the melt and thus increase the acceleration and thus…
However Roderik Van de Waal and colleagues at the Utrecht University in the Netherlands, do not believe this to be the case.
Van de Waal and his team believe that the channels that carry the melt water out to sea freeze up during winter. However in summer, they reopen, and the water that rushes down through the moulins to the bedrock below overwhelm the small channels, and the subsequent pressure lifts the ice-sheet off the rock, enabling it to move faster. However the team have concluded that, after only a few days, the channels are forced open by the water, and it drains away from the glacier, stopping any lubricated slip to damnation.
However not all scientists agree. Jay Zwally of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, believes that averaging the data over the last 17 years – which is what Van de Waal have done – doesn’t make sense. “It’s only in the last five years or so that the warming signal has really been visible,” he says.
So, we’ve either removed a fear from the Earth plummeting in to immediate doom, or not. Either way, science continues on.
Photo Credit Jesse Allen, Earth Observatory
