Washington, July 23 (IANS): The coral reefs that have protected Pacific islanders from storm waves for thousands of years could grow rapidly enough to keep up with escalating sea levels if ocean temperatures do not rise too quickly, says a new study.

Coral reefs are diverse underwater ecosystems held together by calcium carbonate structures secreted by corals.

The study provides the first evidence that well-managed reefs will be able to keep up with sea-level rise through vertical growth. But that can happen only if carbon dioxide levels in the atmosphere stay below 670 parts-per million (ppm).

"Reefs will continue to keep up with sea-level rise if we reduce our emission of greenhouse gases," said Rob van Woesik, a professor in the department of biological sciences, Florida Institute of Technology.

"If reefs lose their capacity to keep up with sea-level rise they will drown," Woesik said in Royal Society Open Science.

Carbon dioxide is the key greenhouse gas responsible for most of global warming, which in turn increases ocean temperatures.

Today, the level of carbon dioxide is 400 ppm and if it crosses 670 ppm even healthy reefs will not be able keep up. Coral reefs are an intricate part of island culture, and they are considered a precious resource in the Pacific Ocean.

If global temperatures continue to rise and thus retard the growth of these natural storm barriers, the homelands of millions of people on lands throughout the Pacific Ocean will be in jeopardy.