Global Warming Threatens Ocean Life
Excess carbon dioxide dissolves in the ocean and disturbs coral, shellfish growth.
Photo 1 of
Divers and snorkelers are all too familiar with one of the consequences of global warming: coral reef bleaching, which happens when rising sea temperatures drive out the symbiotic algae in corals, leaving the reefs colorless. But a new threat is creeping into our waters, also stemming from the same causes as global warming. It's called ocean acidification, and it affects the very foundation of how coral reefs and shellfish grow.
As with global warming, ocean acidification is related to the burning of coal, oil and other fossil fuels -- which pumps carbon dioxide into the air. Much of this carbon dioxide pollution hangs over the earth in a heat-trapping blanket, causing global warming; but some of it is sinking into the ocean, where it dissolves and reacts with water to form carbonic acid.
Carbonic acid interferes with the growth of coral, preventing reefs from growing fast enough to keep up with the natural rate of erosion. It also makes coral skeletons more brittle -- almost like osteoporosis in humans. The combined stress of warming and acidification has many coral reef biologists worried. When coral reefs suffer, the entire community of aquatic life that depends on them for food and shelter falters. In terms of fish alone, that's roughly a quarter of the species swimming in the oceans today.
Shellfish are also at direct risk from ocean acidification because carbonic acid reduces the levels of a critical raw material -- calcium carbonate -- they use to grow their shells. Many creatures at the base of the food chain rely on calcium carbonate. Depending on what our future carbon emissions are, in certain regions ocean life could shift dramatically toward the spineless -- as one scientist put it, to "the reign of jellyfish."
The good news is that the key to preventing the worst outcome is already on the world's to-do list: slashing global warming pollution. Carbon dioxide is the main global warming polluter. By cutting carbon dioxide emissions from cars and power plants, we can curb global warming as well as the acidification of our oceans.
