Coral reefs may be protected by natural ocean ...( BOULDER--Natural processes may preve...)

BOULDER--Natural processes may prevent oceans from warming beyond a certain point, helping protect some coral reefs from the impacts of climate change, new research finds. The study, by scientists at the National Center for Atmospheric Research (NCAR) and Australian Institute of Marine Science (AIMS), finds evidence that an ocean "thermostat" appears to be helping to regulate sea-surface temperatures in a biologically diverse region of the western Pacific.

The research will be published online Saturday in Geophysical Research Letters. It was funded by the National Science Foundation, NCAR's primary sponsor, with support from the U.S. Department of Energy; the Japanese Ministry of Education, Culture, Sports, Science, and Technology; and AIMS.

The research team, led by NCAR scientist Joan Kleypas, looked at the Western Pacific Warm Pool, a region northeast of Australia where naturally warm sea-surface temperatures have risen little in recent decades. As a result, the reefs in that region appear to have suffered relatively few episodes of coral bleaching, a phenomenon that has damaged reefs in other areas where temperature increases have been more pronounced.

The study lends support to a much-debated theory that a natural ocean thermostat prevents sea-surface temperatures from exceeding about 88 degrees Fahrenheit (31 degrees Celsius) in open oceans. If so, this thermostat would protect reefs that have evolved in naturally warm waters that will not warm much further, as opposed to reefs that live in slightly cooler waters that face more significant warming.

"Global warming is damaging many corals, but it appears to be bypassing certain reefs that support some of the greatest diversity of life on the planet," Kleypas says. "In essence, reefs that are already in hot water may be more protected from warming than reefs that are not. This is some rare hopeful news for these important ecosystems."