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Posted at 10:30 AM ET, 11/24/2010

Arctic dust storms: really?

By Steve Tracton

* Showery Thanksgiving: Full Forecast | Forecasts gone awry *

alaska-glacier-dust.jpg
Thin plumes of glacial dust (in beige) blow off the Alaskan coast toward the south-southwest.The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this natural-color image on November 17, 2010. Source: NASA

When one thinks of dust storms, I suspect the mental images that appear include the Dust Bowl of the 1930s in the U.S., West African dust blowing over the Atlantic, and the desert environments of the Middle East, Australia, and China.

But I doubt Alaskan glaciers come to mind. Consider also the occurrence of glacial related dust storms in Iceland and a possible connection to global warming, and head-scratching might be the principle reaction.

I scratched my head when I came across the image of a huge dust storm (shown above) blowing off the Malaspina Glacier in southeastern Alaska on November 17th (one week ago).

And this was not a unique event, for comparable dust storms occurred last November (2009) , November 2005 (especially dramatic photo), and March 2003.

The cause seems obvious, at least in retrospect. As the massive glacier flows towards the sea, it crushes the rock underneath into fine dust, referred to (not so obviously) as glacial flour, and is deposited as mud.

Like most glaciers worldwide, ostensibly due to global warming, the Malaspina Glacier has been retreating for at least the last 30 years. As it retreats, the mud dries and winds carry it far and wide, in this case into the Gulf of Alaska.

Data from a fine-particle collecting site established in 1991 indicates Iceland is also subject to dust storms attributed to retreating glaciers - and possibly over the Arctic more generally. This dust can spread over northern latitudes, including Britain and Europe (and North America?). The principal investigator of this investigation, Joseph Prospero, an atmospheric chemist at the University of Miami, warns that: "These glaciers are retreating, and if they continue to retreat, then you're going to be exposing more of this sub-glacial grinding." And the grinding would lead to more dust fallout.

Should we care? Atmospheric dust affects air temperatures through absorption and scattering of solar radiation, can influence the productivity of marine life and, as potential condensation nuclei of atmospheric water vapor, can affect cloud formation and rainfall.

But, as so true with almost all weather and climate processes, we require better understanding of the complex relations between dust, ice, atmosphere and the oceans, and better measurements of the global distribution and size of airborne particles.

By Steve Tracton  | November 24, 2010; 10:30 AM ET
Categories:  Climate Change, Latest, Science, Tracton  
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Comments

Interesting post. The uncertainty is pretty large as you say. In this article, http://dx.doi.org/10.1016/S0012-8252(01)00041-1 the authors make several claims. First, that manmade climate change causes less natural dust. Second, that a reduction in natural dust is a positive feedback, meaning it could amplify warming (although they don't put it in those terms, I believe that's what they mean).

Here's one prominent example of why there will probably be less dust http://news.nationalgeographic.com/news/2009/07/090731-green-sahara.html

Posted by: eric654 | November 24, 2010 1:24 PM | Report abuse

Eric, I'm aware of these articles (and others) but purposely chose not to get into the role of dust more generally to avoid getting sucked into the morass of climate change back and forth - especially just before a holiday period.

Posted by: SteveT-CapitalWeatherGang | November 24, 2010 2:37 PM | Report abuse

As I recall there were huge dust storms during the Ice Ages...resulting in massive deposits of loess [wind-blown soil] south of the continental glaciers.

Posted by: Bombo47jea | November 24, 2010 11:39 PM | Report abuse

Steve,

Interesting article and picture. Wes

Posted by: wjunker | November 25, 2010 12:03 PM | Report abuse

The comments to this entry are closed.

 
 
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