A coral reef ecosystem off the coast of West Papua, Indonesia | Getty Images

Expanding ‘Dead Zones’ Are Suffocating the World’s Oceans

Climate change, agricultural runoff, and human waste have quadrupled the size of oxygen-depleted areas of the oceans singe 1950, according to a new, comprehensive study.

Low-oxygen zones are spreading around the globe. Red dots mark places on the coast where oxygen has plummeted to 2 milligrams per liter or less, and blue areas mark zones with the same low-oxygen levels in the open ocean. | GO2NE working group. Data from World Ocean Atlas 2013 and provided by R. J. Diaz
Low oxygen caused the death of these corals and others in Bocas del Toro, Panama. The dead crabs pictured also succumbed to the loss of dissolved oxygen. | Arcadio Castillo/Smithsonian