Effects of Deforestation on Spatiotemporal Distributions of Precipitation in South America

Abstract

his study investigates how future deforestation in the Amazon may alter precipitation statistics in South America using a variable-resolution GCM. The model?s grid mesh is set up to cover South America and nearby oceans at mesoscale (25 km) resolution, and then to gradually coarsen and cover the rest of the world at 200-km resolution. Because of the computational efficiency of this approach, it was possible to carry out the first decadal-scale simulations of Amazon deforestation at mesoscale resolution. Unlike traditional mesoscale models, this approach does not require lateral boundary conditions. The results indicate that deforestation reduces simulated precipitation in the Amazon, but this reduction is much smaller than that seen in most previous GCM studies. Furthermore, a subcontinental redistribution of precipitation is found whereby the northwest Amazon becomes drier and the southeast Amazon becomes wetter. During most of the year, these changes are driven by changes in the mean intensity of precipitation events; however, in September?November, changes in precipitation frequency are also important. Large changes in June?August hydroclimate were also found, with extreme cold events becoming more common. These changes have consequences for agriculture, natural ecosystems, and surface hydrology.