The retreat of Greenland's glaciers has been one of the focal points of the Global Warming debate. Data has gone back and forth from both sides. Now, additional research from Danish researches at Aarhus University has added more data to the stack to be considered. The article opens interestingly enough:
Greenland's glaciers have been shrinking for the past century, according to a Danish study, suggesting that the ice melt is not a recent phenomenon caused by global warming.The researchers seemed to use a respectable time period for their study. Of course this is always open to debate. Both sides of the argument accuse the other of selecting a data set that supports their point of view. Anyway, it appears that the data set here is quite inclusive.
Danish researchers from Aarhus University studied glaciers on Disko island, in western Greenland in the Atlantic, from the end of the 19th century until the present day.
Using maps from the 19th century and current satellite observations, the scientists were able to conclude that "70 percent of the glaciers have been shrinking regularly since the end of the 1880s at a rate of around eight meters per year," Yde said.Now, before anyone goes off in any direction. The researchers did point out the following:
"We studied 95 percent of the area covered by glaciers in Disko and everything indicates that our results are also valid for the glaciers along the coasts of the rest of Greenland," he said.
The biggest reduction was observed between 1964 and 1985.
The effect of the rising temperatures in the 1920s and 1930s was "visible dozens of years later, and that of the 1990s will be (visible) in 10 or 20 years," Yde said, adding that he expected Greenland's glaciers to melt even faster in the future.However, additional conclusions by the researchers actually allow the natural warming theory and the human activity induced theory to co-exist.
The shrinking of the glaciers since the 19th century is "the result of the atmosphere's natural warming, following volcanic eruptions for example and greenhouse gases, created by human activities, which have aggravated the situation further," he said.I have never said that Global Warming doesn't exist; but, that I have my doubts about the magnitude of humanity's responsibility for it. I believe the data is still coming in. This study, while admitting that man's activities have aggravated the situation, also points out that the glaciers have been shrinking for longer than expected.
Conversely, there is a bit of information at the end of the article that should be noted as well.
The study also showed new results on galloping glaciers, the name given to glaciers that surge very quickly for a few years, up to 50 meters a day, before advancing more slowly at a rate of 20 meters per year," he said.There are many theories about "galloping glaciers". These range from ice dams or ice shelves that give way and allow the pent up pressure of the glacier to be released to a theory that increased melting "lubricates" the movement of the glacier and increases it's speed. However, glaciologists aren't really sure why the glaciers do that. I found quite a few articles on the web, but this one
"We have identified, thanks to new analyses of aerials photographs and satellite images, almost four times more galloping glaciers, or 75 compared to just 20 in previous estimates," he said.
focuses on glaciers in Alaska and the apparent predictability of the surge cycles.
As I said before, this is all more data to be considered.
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Technorati: Global Warming, Greenland Ice Sheet, Glaciers, Climate Change