Climate change likely to cause surge in nutrient runoff


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A small portion of a hypoxic dead zone in the Chesapeake Bay. (Chesapeake Bay Program)
Jenna Ladd| August 4, 2017

A recent study found that increased precipitation due to climate change will lead to markedly increased nutrient runoff.

Nitrogen rich fertilizers are widely used by U.S. farmers. Many times, more fertilizer than crops can use are applied to the land and the excess runs off into local waterways, eventually draining into the ocean. Excessive nutrient enrichment, also known as eutrophication, decreases available oxygen in the water and kills off aquatic species, resulting in “dead zones.”

Warmer temperatures associated with climate change are expected to continue producing heavier rainfall, thereby increasing nutrient runoff by up to twenty percent by 2100. Anna Michalak, a professor of global ecology at the Carnegie Institution for Science at Stanford and one of the authors of the study, told the New York Times, “When we think about climate change, we are used to thinking about water quantity — drought, flooding, extreme rainfall and things along those lines. Climate change is just as tightly linked to issues related to water quality, and it’s not enough for the water to just be there, it has to be sustainable.”

Researchers concluded that the Upper Mississippi Atchafalaya River Basin, the Northeast and the Great Lakes basin are likely to see the largest increases in nutrient runoff because these areas of the country are already creating hypoxic dead zones. Climate change will likely compound these effects.

While the study focused on the continental U.S., the researchers did apply their model to parts of the world most similar to it. They found that large areas of East, South and Southeast Asia will likely see nutrient runoff surges similar to those in the U.S. Given that some people in these regions depend on surface water to survive, the impacts of nutrient pollution there may be especially lethal.

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