Coral Reef Futures

Can corals adapt?

A recent modeling study shows that widespread bleaching events, like this one in Thailand in 2010, will become more common in the future. However, the study also found signs that corals may be adapting to warming—the question is if it can be fast enough to keep up with the rate humans are burning fossil fuels.

Coral reefs may be able to adapt to moderate climate warming and improve their chance of surviving through the end of this century, if there are large reductions in carbon dioxide emissions. This finding along with data to suggest that corals have already adapted to part of the warming that has occurred so far is part of a study funded by NOAA.

Warm water can contribute to a potentially fatal process known as coral bleaching, in which reef-building corals eject the algae living inside their tissues. Corals bleach when ocean waters warm just 1-2°C (2-4°F) above normal summertime temperatures. Because those algae supply the coral with most of its food, prolonged bleaching and associated disease often kills corals.

This study explored a range of possible coral adaptive responses to warming temperatures previously identified by the scientific community. The study projected that, through genetic adaptation, the reefs could reduce the currently projected rate of temperature-induced bleaching by 20 to 80 percent of levels expected by the year 2100, if there are large reductions in carbon dioxide emissions.

According to the Status of Coral Reefs of the World: 2000 report, coral reefs have been lost around the world in recent decades with almost 20 percent of reefs lost globally to high temperatures during the 1998-1999 El Niño and La Niña and an 80 percent percent loss of coral cover in the Caribbean was documented in a 2003 Science paper.