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Detailed Reference Information |
Sturm, M., Douglas, T., Racine, C. and Liston, G.E. (2005). Changing snow and shrub conditions affect albedo with global implications. Journal of Geophysical Research 110: doi: 10.1029/2005JG000013. issn: 0148-0227. |
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Observations suggest that shrub abundance in the Arctic is increasing owing to climate warming. We investigated the ramifications of a tundra-to-shrubland transition on winter energy exchange. At five sites in Alaska we suspended a 50-m-long cable above the vegetation and from this measured how the vegetation interacted with the snow and affected albedo. The sites defined a gradient from nearly shrub-free tundra to a woodland with a continuous shrub canopy. Where the shrubs were small, thin-stemmed, and supple, they were bent and buried by snow. Where they were tall, thick-stemmed, and stiff, the shrub canopy remained exposed all winter. Where shrubs were buried, mid-winter albedo values were high (0.85), but where they were exposed, the values were 30% lower (0.60). At these latter sites, melting began several weeks earlier but proceeded more slowly. Consequently, all sites were free of snow about the same time. Using the measurements and a solar model, we estimate that a land surface transition from shrub-free tundra to shrubland could produce a 69 to 75% increase in absorbed solar radiation during the snow-cover period, depending on latitude. This is two thirds the increase associated with a tundra-to-forest transition. When combined with measurements showing that a tundra-to-shrub transition would also produce a net increase in summer heating, our results suggest a positive feedback mechanism associated with a warming-induced increase in shrubs. To our knowledge, ours is the first study to document that shrubs could alter the winter energy balance of tundra in such a substantial way. |
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Abstract |
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Keywords
Global Change, Land/atmosphere interactions (1218, 1843, 3322), Biogeosciences, Biosphere/atmosphere interactions, Biogeosciences, Permafrost, cryosphere, and high-latitude processes (0702, 0716), Cryosphere, Tundra, Cryosphere, Snow (1827, 1863), snow, tundra, shrubs |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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