Can Coral Reefs Survive Global Warming?

Corals house symbiotic algae that share their food while painting the reefs vivid colors. A bleached coral, such as this one, is either dead or dying.

There's bad news and good news. The bad news is that after the 1997-98 El Nino warmed waters four degrees Fahrenheit and raised the ocean's levels one inch above average, 60 percent of the globes coral reefs were severely damaged. The good news is that the world's coral reefs may survive past their predicted 2030 demise. When corals get stressed, they lose their symbiotic zooxanthelle, algae that share the food they create through photosynthesis with the corals. The death of the algae leads to bleaching since most of the coral's color comes from the algae. Without the food the light capturing algae provide, the corals die. While corals have survived for hundreds of millions of years by adapting to and recovering from major climate changes-such as ice ages, hurricanes and El Ninos-the question is now whether they are resilient enough to survive the additional stresses placed on them by humans. But researchers have found that some corals may be adapting to the warming waters with a living heat shield. The algae that typically live in corals-Symbiodinium C-have been extensively damaged by warming waters. However the few corals that bleached but didn't die were found to have another related algae called Symbiodinium D. This strategy may demonstrate how coral survived the previous warming trend 220 million years ago. For more information go to: www.nasa.gov/vision/earth/environment/coral.html