Forests have a natural cooling effect for myriad reasons: they cycle water from the ground to the air, where the water takes heat with it as it evaporates (a process called evapotranspiration); their canopies provide shade; and their trees create a rough terrain, which dissipates heat more efficiently than smoother, clear-cut fields. So when forests disappear, the denuded land heats up. But this effect is not limited to the deforested areas, according to the new paper, published last month in Environmental Research Letters.
Paulo Brando, a tropical ecologist at the University of California, Irvine, and the Woods Hole Research Center, who was not involved in the study, cites reduced evapotranspiration as another possible contributor. He says the cumulative effect of the patchwork of clear-cutting is enough to impact the entire region. “As you slow down the capacity of this system to cycle water, you cause regional warming,” he adds.
The researchers say their results could help convince farmers that clearing forest may not be in their own best economic interests, because agriculture is particularly susceptible to temperature changes—last year a rash of heat waves damaged crops around the world. Brazilian farmers are influential in environmental politics and have a strong lobby in the national government, Cohn says. Showing them that deforestation nearby can significantly increase surface temperatures in their fields—potentially killing crops as a result—could coax them to consider conservation measures. “Protecting the environment can have private returns to the landholder,” he says. “Understanding the future of agriculture and how it relates to conservation is incredibly important to help farmers make informed decisions about the right balance between production and protection.”
This story is part of Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.
