Global albedo change and radiative cooling from anthropogenic land cover change, 1700 to 2005 based on MODIS, land use harmonization, radiative kernels, and reanalysis

Abstract

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 has been partially offset 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 Moderate Resolution Imaging Spectroradiometer with a historical land use data set (Land Use Harmonization product) to provide more precise, observationally derived estimates of albedo impacts from anthropogenic land cover change with a complete range of data set specific uncertainty. The mean annual global albedo increase due to land cover change during 1700-2005 was estimated as 0.00106 ± 0.00008 (mean ± standard deviation), mainly driven by snow exposure due to land cover transitions from natural vegetation to agriculture. This translates to a top-of-atmosphere radiative cooling of À0.15 ± 0.1 W m À2 (mean ± standard deviation).Our estimate was in the middle of the Intergovernmental Panel on Climate Change Fifth Assessment Report range of À0.05 to À0.25 W m À2 and incorporates variability in albedo within land cover classes.

Multiscale climatological albedo look-up maps derived from moderate resolution imaging spectroradiometer BRDF/albedo products

“…Global albedo change and radiative cooling from anthropogenic land cover change were investigated. 21 The study found that the mean annual global albedo was increased due to land cover transitions from natural vegetation to agriculture during 1700 to 2005. 21 …”

“…The LUH product describes spatially explicit fractional land use patterns and annual transitions for both historical (1500 to 2005) and future (2005 to 2100) scenarios at a 0.5 deg resolution within five classes: croplands, urban, pasture, primary and secondary lands, and water/ice. 11,12 These five classes were converted to different proportions of IGBP 17 land cover classes based on a pixelspecific map intersection at 1 deg with the 30 arcsec 1992 to 1993 AVHRR IGBP product of Eidenshink and Faudeen (1994) for the period of overlap, as described in Ghimire et al 21 LUH cropland and urban classes were directly mapped to the same IGBP classes, while pasture was mapped to shrublands, savannas, and/or grasslands, and primary and secondary lands were mapped to forests, shrublands, savannas, and/or grasslands, each based on pixelscale proportions. This mapping rule was assumed to be temporally invariant and was applied across time.…”

“…The resulting albedos were compared to the standard MODIS albedo products. The application of the modeled albedos for 1500 to 2100 based on the LUH land use maps are presented and analyzed separately in Ghimire et al 21 The major steps in Fig. 1 are discussed in the following subsections.…”

Empirically Derived Sensitivity of Vegetation to Climate across Global Gradients of Temperature and Precipitation

“…Structure and productivity of vegetation are also controls on the terrestrial carbon cycle (Friedlingstein et al 2006), the terrestrial hydrological cycle (Schlesinger and Jasechko 2014;Jasechko et al 2013), and the surface energy budget (Ghimire et al 2014). To understand how global vegetation will be altered under climate change, we must understand how ecological-climate interaction operates at large spatial scales and thus across global climate gradients.…”

Areal-Averaged Spectral Surface Albedo in an Atlantic Coastal Area: Estimation from Ground-Based Transmission

“…Knowing that surface albedo substantially affects the variability of the Earth's radiation balance [1], and that this variability is sensitive to multiple natural and man-made factors [2], the importance of monitoring the surface albedo from ground, air and space [3][4][5][6][7] is increasingly recognized. The assessment of these variations is challenging for heterogeneous regions where complex landscapes with distinctive land cover types occur.…”