September 09, 2007
|Greenland Melt Accelerates||Environment|
Greenland ice is melting so quickly now that chunks breaking off are so huge they trigger earthquakes. Glacier flow is three times faster than it was just 10 years ago. Guardian:
The Greenland ice cap is melting so quickly that it is triggering earthquakes as pieces of ice several cubic kilometres in size break off.
Scientists monitoring events this summer say the acceleration could be catastrophic in terms of sea-level rise and make predictions this February by the Intergovernmental Panel on Climate Change far too low.
The glacier at Ilulissat, which supposedly spawned the iceberg that sank the Titantic, is now flowing three times faster into the sea than it was 10 years ago.
Robert Corell, chairman of the Arctic Climate Impact Assessment, said in Ilulissat yesterday: "We have seen a massive acceleration of the speed with which these glaciers are moving into the sea. The ice is moving at 2 metres an hour on a front 5km [3 miles] long and 1,500 metres deep. That means that this one glacier puts enough fresh water into the sea in one year to provide drinking water for a city the size of London for a year."
He is visiting Greenland as part of a symposium of religious, scientific, and political leaders to look at the problems of the island, which has an ice cap 3km thick containing enough water to raise worldwide sea levels by seven metres. [...]
He had flown over the Ilulissat glacier and "seen gigantic holes in it through which swirling masses of melt water were falling. I first looked at this glacier in the 1960s and there were no holes. These so-called moulins, 10 to 15 metres across, have opened up all over the place. There are hundreds of them."
This melt water was pouring through to the bottom of the glacier creating a lake 500 metres deep which was causing the glacier "to float on land. These melt-water rivers are lubricating the glacier, like applying oil to a surface and causing it to slide into the sea. It is causing a massive acceleration which could be catastrophic."
The glacier is now moving at 15km a year into the sea although in surges it moves even faster. He measured one surge at 5km in 90 minutes - an extraordinary event.
Veli Kallio, a Finnish scientist, said the quakes were triggered because ice had broken away after being fused to the rock for hundreds of years. The quakes were not vast - on a magnitude of 1 to 3 - but had never happened before in north-west Greenland and showed potential for the entire ice sheet to collapse.
Dr Corell said: "These earthquakes are not dangerous in themselves but the fact that they are happening shows that events are happening far faster than we ever anticipated." [Emphasis added]
The one constant in all these global warming stories seems to be that everything is happening much faster than even the worst case predictions. It's important to realize that the ice doesn't all have to melt outright. As melt water gets under the ice sheet, breaks its hold on the rock below, and turns the rock into a slippery slope, the ice can just slide into the sea and melt there. These kinds of effects can be quite sudden, as is being seen. A glacier moving 5 km in 90 minutes — that's stunning.