With little rain falling throughout the summer, water failed to wash pollutants like nitrogen and phosphorous from agricultural land and city streets into streams and rivers. Usually these pollutants end up in the oceans, feeding huge algae blooms. After the algae die, their decomposition consumes oxygen and creates hypoxic areas, or dead zones. This year, the size of the dead zone in the Chesapeake Bay was the smallest — and the dead zone in the Gulf of Mexico nearly the smallest – since record-keeping began in in 1985.
But extreme weather can expand dead zones as easily as this year’s drought reduced them. As an article published by the World Resources Institute points out, rising temperatures, changing patterns and increasingly frequent intense weather events will alter aquatic systems as well as agricultural practices and cause larger and longer-lasting hypoxic zones in the future.