Dr. Michael T. Coe studies how soybean farms and cattle ranching replace Amazon forest and disrupt water cycles. His field data from Mato Grosso shows deforestation reduces rainfall and raises temperatures across the entire basin, potentially making the climate unsuitable for tropical forest even in protected areas.
Hi, I'm Michael Koh, senior scientist at the Woods Hole Research Center. I study how human modifications of climate and the landscape alter water resources. Most of my current work is in the Amazon Basin, where deforestation, primarily for soybean production and cattle production, is rapidly changing the landscape, which in turn changes water resources through alteration of river discharge and rainfall.
So we come at this problem from two angles. One, we collect data in the field. We currently have a large instrument installation in Mato Grosso Braz, in the center of the Amazon, where we study how deforestation changes the amount of water that runs into streams. We do that by installing level loggers in the streams that measure how the level of the water changes with time. And we also measure the velocity of the water. And from that, we can deduce the total amount of water flowing in these streams. And we do this in streams, in pasture, in soy, and in forests. The second way we do this is we apply computer models with the data we've collected in the field to better understand how these local changes scale up to be very large changes across the entire Amazon basin. The advantage of a computer model is I can make all kinds of experiments that I could not possibly do in the field. I can deforest very large sections of the Amazon in order to understand how that would affect the water resources.
Our observations and computer modeling studies suggest that replacing large areas of forest with great grass or seasonal crops can cause changes in the atmosphere that lead to decreased water recycling, higher temperatures, and decreased rainfall. These changes may, in some cases, create a new climate that will not sustain the tropical forests. Therefore, deforestation and the related climate changes could threaten the existence of tropical forests in general, including those in protected areas distant from where deforestation is currently occurring. The effects of deforestation on water resources is not unique to the Amazon. We can apply these same sorts of scenarios to other locations in the tropics, such as Africa and Indonesia, where the negative impacts of deforestation on water resources are equally important.
