Converting rainforest to cropland in Africa reduces rainfall

September 19 (www.mongabay.com) – Converting West African rainforests into cropland reduces rainforest in adjacent forest areas, reports research published in Geophysical Research Letters. The study, based on a computer model used to simulate rainfall under different land-use conditions, found that cutting down tropical forests in West Africa reduces precipitation over neighboring forest areas by about 50 percent due to increased temperatures over cropland areas. Higher temperatures affect the formation of rain clouds. “Rainfall was four to six times higher over warm areas (cropland) than when no deforestation has occurred, while rainfall over the remaining forest was half or less,” stated a press release from the American Geophysical Union, which publishes Geophysical Research Letters. “The difference in rainfall is caused by the temperature change between cropland and forest, which produces winds that converge over the crop area and form clouds.” The researchers say their work, while applied to a small region, could have implications elsewhere. “We already know from satellite observations that changes in land use can have a big impact on local weather patterns,” said lead author Luis Garcia-Carreras with the University of Leeds School of Earth and Environment. “Here we have been able to show why this happens.” “Our findings suggest that it’s not just the number of trees removed that threatens the stability of the world’s rainforests. The pattern of deforestation is also important.” […]