Climate Change Expanding Dead Zones in Great Lakes, Other Waters | OnEarth Magazine

Climate Change Expanding Dead Zones in Great Lakes, Other Waters | OnEarth Magazine
Nitrogen and phosphorous-laden sediments flowing into Lake Erie from inland sources are a primary cause of oxygen-starved dead zones. This animation shows sediment plumes in Lake Erie during March 2010.

Areas of low oxygen are 30 times more prevalent in the nation’s waterways now than they were in 1960, according to a recent federal report. And climate change means they will continue to worsen.

The multi-agency report [PDF, 2.7 MB], released in September, states that the low-oxygen condition known as hypoxia has been detected in half of the more than 600 national waterways analyzed by the National Oceanic Atmospheric Administration, the U.S. Geological Survey, the U.S. Environmental Protection Agency, and the U.S. Department of Agriculture.

Hypoxia is often caused by increased nutrients such as phosphorous and nitrogen. These common components of fertilizer often enter lakes and streams with runoff from farms and lawns. Nitrogen released into the atmosphere from fossil fuel combustion can also settle onto the water’s surface.

“What we do affects the amount of nutrients that wash off the land and are ultimately carried by rivers to the coast,” said report co-author Herb Buxton, coordinator of the Geological Survey’s program on toxic substances hydrology. “Runoff is the conveyer belt for moving nutrients from the landscape to our coastal systems.”