Coral reefs may start dissolving when CO2 doubles

Washington, March 10 (ANI): In a new study, scientists have determined that if carbon dioxide (CO2) reaches double pre-industrial levels, coral reefs can be expected to not just stop growing, but also to begin dissolving all over the world.

The study, by researchers at the Carnegie Institution and the Hebrew University of Jerusalem, points out that the impact on reefs is a consequence of both ocean acidification caused by the absorption of CO2 into seawater and rising water temperatures.

"Globally, each second, we dump over 1000 tons of carbon dioxide into the atmosphere and, each second, about 300 tons of that carbon dioxide is going into the oceans," said co-author Ken Caldeira of the Carnegie Institution's Department of Global Ecology.

"We can say with a high degree of certainty that all of this CO2 will make the oceans more acidic," he added.

The study was designed to determine the impact of this acidification on coral reefs.

The research team used field data from coral reefs to determine the effects of temperature and water chemistry on coral calcification rates.

Armed with this information, they plugged the data into a computer model that calculated global seawater temperature and chemistry at different atmospheric levels of CO2 ranging from the pre-industrial value of 280 ppm (parts per million) to 750 ppm.

Based on the model results for more than 9,000 reef locations, the researchers determined that at the highest concentration studied, 750 ppm, acidification of seawater would reduce calcification rates of three quarters of the world's reefs to less than 20 percent of pre-industrial rates.

Field studies suggest that at such low rates, coral growth would not be able to keep up with dissolution and other natural as well as manmade destructive processes attacking reefs.

Prospects for reefs are even gloomier when the effects of coral bleaching are included in the model.

Coral bleaching refers to the loss of symbiotic algae that are essential for healthy growth of coral colonies.

According to their model, the researchers calculated that under present conditions, 30 percent of reefs have already undergone bleaching and that at CO2 levels of 560 ppm, the combined effects of acidification and bleaching will reduce the calcification rates of all the world's reefs by 80 percent or more.

This lowered calcification rate will render all reefs vulnerable to dissolution, without even considering other threats to reefs, such as pollution.

"Our fossil-fueled lifestyle is killing off coral reefs," said Caldeira. "If we don't change our ways soon, in the next few decades we will destroy what took millions of years to create," he added. (ANI)