Map of Dead Zones: climate change is killing marine life | Illustration: Smithsonian Institution

A study led by the Smithsonian Institution concluded that nearly all ocean dead zones will increase by the end of the century because of climate change.

Dead zones are areas in the ocean where oxygen levels are so low that marine life either dies or leaves the area. In other words, they are healthy marine environments that became uninhabitable.

Global warming plays a critical role in the development of dead zones because, as temperatures increase, marine life needs more oxygen to survive. Scientists believe dead zones have doubled every ten years, since the 1960s.

"Climate change will drive expansion of dead zones, and has likely contributed to the observed spread of dead zones over recent decades," confirm Andrew Altieri and Keryn Gedan, researchers of the Smithsonian Tropical Research Institute, in Panama and Maryland.

Dead zones often occur when runoff drains into the ocean and loads up the water with excess nutrients such as nitrogen and phosphorus. Those nutrients kill organisms. The following decomposition sucks up oxygen from the water, leaving little available for fish and marine life.

Scientists studied a database of more than 400 dead zones worldwide. Some 94 percent of these hypoxic areas will experience warming of 3.6 degrees Fahrenheit or more by the end of the century.