Incorporating Biogeophysical Factors in Climate Effect Analysis of Perennial Bioenergy Crops Show Net Cooling Effect

Scientists from the Arizona State University, Stanford University, Carnegie Institution for Science (all in the United States) report the use of a Weather Research and Forecasting (WRF) Model to evaluate the climate effects of converting agricultural areas in the central United States to perennial crops for bioenergy production. Examples of these bioenergy crops include, perennial grasses (switchgrass, Panicum Virgatum L. or miscanthus, Miscanthus X giganteus).

One difference in their approach is the accounting of biogeophysical impacts on climate, "by considering properties that directly influence the manner in which energy is absorbed at the surface and redistributed to the overlying atmosphere". Their study showed that the biogeophysical effects resulting from the hypothetical conversion of annual-to-perennial bioenergy crops across the central United States impart a significant local-to--regional cooling. This cooling, they say, would have considerable implications for the reservoir of stored soil water. Increases in transpiration and higher albedo (reflectivity of the surface) were considered as factors to the cooling effect. A carbon emissions reduction of 78 tons per hectare can be potentially realized. This figure in emissions reduction is said to be about six times larger than the annual biogeochemical effects that arise from the offsetting of fossil fuel use).

Their study demonstrated that biogeophysical effects are important aspects of climate impacts of biofuels, even at the global scale. The full report of their study is published in the Proceedings of the National Academy of Sciences (PNAS) (URL above).