A new study shows that removing trees not only spews carbon into the atmosphere, but also causes major shifts in rainfall and increases temperatures around the world. This double whammy to the climate could have a devastating impact on farmers and global food production.
The study, “Effects of Tropical Deforestation on Climate Change and Agriculture”, found that deforestation in South America, Southeast Asia and Africa may alter growing conditions in agricultural areas in the tropics and as far away as the American Midwest, Europe and China.
“Tropical deforestation delivers a double whammy to the climate – and to farmers,” said the study’s lead author Deborah Lawrence from the University of Virginia. “Most people know that climate change is a dangerous global problem, and that it’s caused by pumping carbon into the atmosphere. But it turns out that removing forests alters moisture and air flow, leading to changes – from fluctuating rainfall patterns to rises in temperatures – that are just as hazardous, and happen right away.”
According to the study, the atmospheric impacts resulting from complete tropical deforestation could lead to a rise in global temperature of 0.7 degrees Celsius (on top of the impact from greenhouse gases), which would double the observed global warming since 1850.
And while complete deforestation is unlikely, clearing trees in the tropics is already affecting local and regional climates. In Thailand, for instance, the beginning of the dry season is experiencing less rainfall due to deforestation, while in deforested regions in the Amazon, the wet season has been delayed by two weeks when compared to forested regions.
But the models show that the impacts will be felt far beyond the tropics, and the variations in rainfall and spikes in temperature could affect some of the world’s most important agriculture regions.
“Farmers, so reliant on consistent and reliable growing conditions, could lose their bearings and even their incomes, when facing these ups and downs in temperature and rainfall,” Lawrence said. “While farmers may ultimately adapt to shifts in the season, it’s difficult – if not impossible – for farmers to adapt to increased floods or parched soils.”
Lawrence argues that climate-change negotiators and other policymakers should take the impacts of deforestation seriously. “What happens on the surface of the earth (in terms of changes in vegetation) is a big factor in climate change. We ignore it at our own peril.”