Thursday, August 18, 2011

Greenland 2011: melt records fall again

Mittivakkat Glacier, seen above, has suffered its most significant ice loss ever recorded -- the biggest decline since at least 1931, probably 1898:

The observations indicate that the total 2011 mass budget loss was 2.45 metres, 0.29 metres higher than the previous observed record loss in 2010. The 2011 value was also significantly above the 16-year average observed loss of 0.97 metres per year.

The 2011 observations further illustrate, even comparing the mass balance value against simulated glacier mass balance values back to 1898, that 2011 is a record-breaking glacier mass loss year.

The melt season in Greenland now stretches into September, so it will likely be early 2012 before we know if the 2011 Greenland melt season has broke 2010's record. But Mittivakkat Glacier appears to be representative of a large classes of similar glaciers:

These observations suggest that recent Mittivakkat Glacier mass losses, which have been driven largely by higher surface temperatures and low precipitation, are representative of the broader region, which includes many hundreds of local glaciers in Greenland. Observations of other glaciers in Greenland show terminus retreats comparable to that of Mittivakkat Glacier. These glaciers are similar to the Mittivakkat Glacier in size and elevation range.

So a new record seems more likely than not. The basics on the Greenland ice sheet are:

* It holds about 700,000 cubic miles of ice, enough to raise sea levels by 20 feet.
* It is melting, and that melt is rapidly accelerating:

* If the melt would stop accelerating, it would take a long time (many thousands of years) to melt the whole thing. Unfortunately, there's no reason to think the acceleration will stop.

For more on Greenland's ice, check out our newly blog-rolled Cryospheric Processes Laboratory.

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