New Article On The Role Of Landscape Processes Within The Climate System by Barnes and Roy In Geophysical Research Letters

There is an important new paper on the role of landscape processes within the climate system [and thanks to Tobis Rothenberger at the University of St. Gallen for alerting us to it!].  The article is

Barnes, C. A., and D. P. Roy (2008), Radiative forcing over the conterminous United States due to contemporary land cover land use albedo change, Geophys. Res. Lett., 35, L09706, doi:10.1029/2008GL033567.

The abstract reads

“Recently available satellite land cover land use (LCLU) and albedo data are used to study the impact of LCLU change from 1973 to 2000 on surface albedo and radiative forcing for 36 ecoregions covering 43% of the conterminous United States (CONUS). Moderate Resolution Imaging Spectroradiometer (MODIS) snow-free broadband albedo values are derived from Landsat LCLU classification maps located using a stratified random sampling methodology to estimate ecoregion estimates of LCLU induced albedo change and surface radiative forcing. The results illustrate that radiative forcing due to LCLU change may be disguised when spatially and temporally explicit data sets are not used. The radiative forcing due to contemporary LCLU albedo change varies geographically in sign and magnitude, with the most positive forcings (up to 0.284 Wm−2) due to conversion of agriculture to other LCLU types, and the most negative forcings (as low as −0.247 Wm−2) due to forest loss. For the 36 ecoregions considered a small net positive forcing (i.e., warming) of 0.012 Wm−2 is estimated.”

The conclusion includes the text

” Loss of agricultural and forested lands were observed to be the LCLU changes that caused the greatest absolute albedo induced forcing. Across the CONUS however there is no single profile of LCLU change, rather, there are varying pulses affected by clusters of change agents [Loveland et al., 2002]. This argues strongly for the ecoregion based analysis we have described, as continental averages may mask regional differences; indeed, because of the variability in magnitude and sign of forcing, we estimate only a small, 0.012 Wm−2, net CONUS forcing due to contemporary LCLU albedo change. This work did not consider snow, which may have a significant land cover dependent albedo effect [Jin et al., 2002] and so may impact the forcing associated with actual albedo change [Betts, 2000]; however, only about one eighth of the CONUS ecoregions considered in this study have significant annual snow cover. Further research will be undertaken to address these impacts for a larger number of ecoregions as more LCLU change data become available.”

This study is yet another example of why we need to include the assessment of landscape on the regional scale, as altered by humans, in terms of how our climate is being changed.

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