Climate Simulation Shows Amazon Deforestation Leads to Water and Food Shortages in the US

If the Amazon rainforest were completely deforested it would significantly reduce rain and snowfall in the western United States, leading to water and food shortages and a greater risk of forest fires, according to climate simulation research lead by Princeton University.

The climate model suggests that if the Amazon were stripped bare, it could lead to a 20 percent reduction in rainfall in the coastal Northwest and up to 50 percent less snowfall in the Sierra Nevada, a crucial water source for cities and farms in California.

Previous research has suggested that Amazon deforestation would result in a mass of dry air over the Amazon. This latest study builds upon previous work, modeling the path of the dry air as natural weather systems carry it directly over the western US from December to February.

"The big point is that Amazon deforestation will not only affect the Amazon -- it will not be contained. It will hit the atmosphere and the atmosphere will carry those responses," David Medvigy, an assistant professor of geosciences at Princeton and first author of the study.

"It just so happens that one of the locations feeling that response will be one we care about most agriculturally," he said. "If you change the snowpack in the Sierra Nevada, where most of the irrigation for California's Central Valley comes from, then by this study deforestation of the Amazon could have serious consequences for the food supply of the United States."

Amazon deforestation is an ongoing environmental issue, but the researchers admit the total-deforestation scenario they used for their model is "an exaggerated level of destruction needed to produce a noticeable effect."

Medvigy said the study highlights the similarities between Amazon deforestation -- the effects of which are unknown -- and El Niño, which has been studied extensively.

"Our intention with this paper was to identify an analogy between El Niño and Amazon deforestation. There's good reason to believe there will be strong climatic similarities between the two. Research like this will give us a handle on what to expect from Amazon deforestation," he said.

Medvigy added that the size and vulnerability of the Amazon rainforest, accompanied by its outsized sway over the climate, make understanding how the rainforest's disappearance will affect the overall climate a topic worth researching.

"We know the Amazon is being deforested, but we don't know for sure what's going to happen because of it," Medvigy said. "Other scientists need to do these simulations and see if they get the same results. If they do, then policymakers will have to take notice."

The research is published in the Journal of Climate Change.