A new study found that global warming could have a more significant effect on dead zones in rivers, oceans and lakes all over the world than previously believed. The study also says that matters will only deteriorate.
A dead zone is the result of fertilizer runoff blocking the waterway with nitrogen, phosphorous and other nutrients, which results in a microbe eruption. These microbes then consume all the oxygen in the water, which in turn hurts aquatic life.
Scientists have been aware for a long time that the warmer the water is, the worse this problem gets. However, a new study that was published in the Global Change Biology journal by the Smithsonian Institute stated that scientists had found approximately twenty-four different biological, physical and chemical ways in which global warming is making oxygen depletion worse.
Andrew Altieri, the lead author for the study and a researcher in Panama at the tropical center of the Smithsonian, said that the effects of climate change on these dead zones had been underestimated.
Thus, the scientists studied 476 dead zones all over the world, of which 264 were in the United States. Using standard computer climate models to predict change, they found that the temperature of the surface in those regions would rise by approximately four degrees Fahrenheit by the end of the century from the temperatures registered in the 1980s and 1990s. The most significant change is expected in Canada, where the St. Lawrence River flows into the ocean, where a seven-degree increase has been predicted. The most significant dead zones in the US are Chesapeake Bay, which is expected to see temperatures higher by almost five degrees, and the Gulf of Mexico, which is predicted to register increases of four degrees.
According to the co-author of the study, Keryn Gedan from the Smithsonian and the University of Maryland, the problem is that the warmer the water is, the less oxygen it contains, which compounds the fertilizer runoff issue. Another effect warm water has in dead zones is that it makes it more difficult for the deeper waters, which contain less oxygen from the get-go, to mix with more oxygenated surface water.
Altieri likens it to Italian dressing that hasn’t been shaken, where you can clearly see the separation between the water and the oil.