Resource information
Widespread anthropogenic land-cover change over the last five centuries has influenced the global climate system through both biogeochemical and biophysical processes. Models indicate that warming from carbon emissions associated with land cover conversion have been partially offset if not outweighed by cooling from elevated albedo, but considerable uncertainty remains partly because of uncertainty in model treatments of albedo. This study incorporates a new spatially and temporally explicit, land-cover specific albedo product derived from MODIS with historical land use dataset (Land Use Harmonization product; Hurtt et al., 2006) to provide more precise, observationally-derived estimates of albedo impacts from anthropogenic land-cover change. The mean annual global albedo increase due to land-cover change during 1700-2005 was estimated as 0.0012, mainly driven by snow exposure due to land-cover transitions from natural vegetation to agriculture. This translates to a top-of-atmosphere (TOA) radiative cooling of -0.23 W m-2. Our estimate of radiative forcing from land cover change is slightly higher than other recent estimates based on MODIS albedo products, and at the higher end of the IPCC AR5 range of -0.25 to -0.05 W/m2.
