Arctic dust storms: really?
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.
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.
| November 24, 2010; 10:30 AM ET
Categories: Climate Change, Latest, Science, Tracton
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