18 July 2007

Glacier Follow-up

Since posting Ice: Going, going... a few days past, several more articles regarding the glaciers have been released. The tone of that post is still in evidence. Glaciers are in retreat around the world.

D.P. Dobhal, a glaciologist who has spent three years climbing and poking the Chorabari glacier, stands at the edge of the snout and points ahead. Three years ago, the snout was roughly 27 meters, or 90 feet, farther away. On a map drawn in 1962, it was plotted 262 meters from here...

A recent study by the Indian Space Research Organization, using satellite imaging to gauge the changes to 466 glaciers, has found more than a 20 percent reduction in size from 1962 to 2001, with bigger glaciers breaking into smaller pieces, each one retreating faster than its parent. (See also this note at Oil Change.)

The problem is not simply that the Aletsch is melting, scientists say. Glaciers have melted for 2,500 years in Europe; at one ice-age point, the Aletsch nearly covered local mountain peaks. What concerns scientists is the pace of the melt.

"Yes, it should retreat, but not so fast. The glacier is in rapid retreat, which is a fact and a clear sign of climate change," Mr. Albrecht says.

In the past 30 years, studies show, the Aletsch has been losing 50 meters of length a year and is thinning. Some years show gains in length, others record losses. But the overall figure is one of shrinkage. Last year, it lost 115 meters – though in 2004 and 2005, the glacier gained about 50 meters per year.

"At this rate, by 2100 about 80 percent of the surface of the glacier will be gone," says Ralph Logon, a Swiss geomorphologist and expert on glaciers.

The remarks of the Swiss highlight the complexities involved in glacial advancement and retreat. This was also noted in the remarks on Kilimanjaro in my previous post and in the selections from Status of the Siachen Glacier In The Himalayas – Climate Science: Roger Pielke Sr. Research Group Weblog. This glacier is apparently one of the larger glaciers in the Himalayas and has demonstrated a complex behaviour of advances and retreats since records began in 1862.

So, the behaviour of glaciers is complex, but I don't feel that a few counter-examples of non glacier-melting negates the general consensus of rapid glacial reduction in association with anthropogenic climate change. I think that the evidence for this consensus conclusion is overwhelming.

Yes, the dynamics of glaciers needs to be better understood in order to place these findings in a broader context. They should not be taken as a call for non-action on the climate. We cannot wait until we have absolute certainty if we wish to ease the multiple threats posed by climate change.

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