CSUMB professor's research indicates the possibility of survival
A study by scientists at Cal State University Monterey Bay, the University of British Columbia and the National Oceanic and Atmospheric Administration provides evidence that coral reefs may be able to adapt to moderate climate warming, improving their chance of surviving through the end of this century.
Results suggest corals have already adapted to part of the warming that has already occurred.
Warm water can cause a potentially fatal process known as coral “bleaching,” in which the beautiful reef-building corals eject algae living inside their tissues. Corals bleach when oceans warm only 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.
“While earlier modeling work suggested that coral reefs would be gone by the middle of this century, our study shows that if corals can adapt to warming over the past 40-60 years some coral reefs may persist through the end of this century,” said study lead author Cheryl Logan, an assistant professor in CSUMB’s Department of Science and Environmental Policy.
The study, published online in the journal Global Change Biology, explores a range of possible coral adaptive responses proposed by the scientific community. It provides a more hopeful outlook for the future of coral reefs than past work that ignored adaptation – but with some important caveats.
“Not all species will be able to adapt fast enough or to the same extent, so coral communities will look and function differently than they do today,” said Logan.
The other authors of the paper were John Dunne from the NOAA Geophysical Fluid Dynamics Laboratory; Mark Eakin from NOAA’s Coral Reef Watch, and Simon Donner from the Department of Geography at the University of British Columbia. NOAA’s Coral Reef Conservation Program funded the study.
“The hope this work brings is only achieved if we significantly reduce our emission of heat-trapping gases,” said Mark Eakin, Ph.D., who serves as director of the NOAA Coral Reef Watch monitoring program which tracks bleaching events worldwide. “Adaptation provided no significant slowing in the loss of coral reefs at the rate we are now emitting carbon dioxide.”
Tropical coral reef ecosystems are among the most diverse in the world, and provide economic and social stability to many nations in the form of food security and economic revenue. Mass coral bleaching and death has increased around the world over the past three decades, raising questions about the future of coral-reef ecosystems.
In the study, researchers used global sea surface temperature output from the NOAA/GFDL Earth System Model-2 for the pre-industrial period though 2100 to project rates of coral bleaching.
Because initial results showed that past temperature increases should have bleached reefs more often than has actually occurred, researchers looked into ways that corals may be able to adapt to warming and delay the bleaching process. This would keep reefs healthier longer despite climate change.
The study projected that, through genetic adaptation, the reefs could reduce the currently projected rate of bleaching by 20 to 80 percent of levels expected by the year 2100 if there are large reductions in carbon dioxide emissions.
The article calls for further research to test the rate and limit of different adaptive responses for coral species across latitudes and ocean basins to determine if and how much corals can actually respond to increasing thermal stress.
The research article is available here.