The threat of the Greenland ice sheet slipping ever faster into the sea because of warmer summers has been ruled out by a scientific study.
Until now, it was thought that increased melting could lubricate the ice sheet, causing it to sink ever faster into the sea. The issue was a key unknown in the landmark 2007 report from the Intergovernmental Panel on Climate Change, which pinned the blame for climate change firmly on greenhouse gas emissions from human activities.
Researchers had feared that more melting from the surface of the ice in hotter years would in turn provide more meltwater for a slippery film at the sheet’s base. More melting would mean more slippage and a greater rise in the sea level.
But they discovered that, above a certain threshold, the slipping began to slow. On-the-ground studies and work done on alpine glaciers suggest that higher volumes of meltwater form distinct channels under the ice, draining the water more efficiently and reducing the formation of a lubricating film.
The Greenland ice sheet studied by Shepherd’s team is up to 1,000m (3,280ft) thick. If the entire ice sheet melted, sea levels would rise by a catastrophic seven metres, but this is likely to take 3,000 years if warm air blowing over the ice is the only way in which the ice melts.
More evidence that what we face is not an immediate and catastrophic problem, but a chronic and long term one.
Greenland melting in full is now pencilled in for 5,010 AD*. Rather a lot of things will change by then: while I’ll not be around to see it of course I’d rather expect there to be a Space Elevator by then for example.
What amuses, I have to say though, is that they’ve reached this conclusion by noting that water flowing downhill, in quantity, seems to form streams and rivers rather than flowing as a sheet down the side of the hill.
You don’t say?
* I have a feeling that they’ve got that 3,000 wrong and that it might actually be 300 but it’s still not an immediate problem.