On the influence of shrub height and expansion on northern high latitude climate

By C. Bonfils, T. J. Phillips, David M. Lawrence, P. Cameron-smith, W. Riley, Z. Subin. 2012

200 citations recorded by the source corpus.

There is a growing body of empirical evidence documenting the expansion of shrub vegetation in the circumpolar Arctic in response to climate change. Here, we conduct a series of idealized experiments with the Community Climate System Model to analyze the potential impact on boreal climate of a large-scale tundra-to-shrub conversion. The model responds to an increase in shrub abundance with substantial atmospheric heating arising from two seasonal land–atmosphere feedbacks: a decrease in surface albedo and an evapotranspiration-induced increase in atmospheric moisture content. We demonstrate that the strength and timing of these feedbacks are sensitive to shrub height and the time at which branches and leaves protrude above the snow. Taller and aerodynamically rougher shrubs lower the albedo earlier in the spring and transpire more efficiently than shorter shrubs. These mechanisms increase, in turn, the strength of the indirect sea-ice albedo and ocean evaporation feedbacks contributing to additional regional warming. Finally, we find that an invasion of tall shrubs tends to systematically warm the soil, deepen the active layer, and destabilize the permafrost (with increased formation of taliks under a future scenario) more substantially than an invasion of short shrubs.

Subfields: Atmospheric Science

View Paper: https://www.semanticscholar.org/paper/26055a512d2e77173eadb1155346d4959f67d7a5

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In Atmospheric Science

Citations in the corpus

Permafrost thaw and resulting soil moisture changes regulate projected high-latitude CO2 and CH4 emissions (2015, background): “…et al 2014), depth dependence of decomposition rates (Koven et al 2015), vegetation feedbacks (Lloyd et al 2003, Lawrence and Swenson 2011, Bonfils et al 2012), heterogeneity in permafrost thaw and related hydrologic responses (Painter et al 2013), and the modulating role that Content…”
Tundra shrubification and tree-line advance amplify arctic climate warming: results from an individual-based dynamic vegetation model (2013, background): “The current observed shrub expansions, tree-line advances and species shifts could likely decrease local surface albedo, exacerbating regional warming (Shuman et al 2011, Bonfils et al 2012, Miller and Smith 2012).”