Global Warming

Scientists turn chief global warming gas into harmless stone

Scientists have a found a quick way but not a cheap one to turn heat-trapping carbon dioxide gas into harmless rock.

Experts say the results of a two-year, $10 million experiment called CarbFix, conducted about one-third of a mile (540 meters) deep in the rocks of Iceland, offer new hope for an effective weapon to help fight man-made global warming.

When an international team of scientists pumped a carbon dioxide and water mix into underground basalt rocks, basic chemistry took over. The acidic mixture dissolved the rocks' calcium magnesium and formed limestone, a permanent natural jail for the heat-trapping gas, according to Juerg Matter of the University of Southampton in England. He is the lead author of a study detailing the experiment published Thursday in the journal Science.

"It's no longer a gas," Matter said. "Basically carbon dioxide is converted into stone."

Scientists, who had done this before in the lab, thought the process could take thousands or even hundreds of thousands of years. But after just two years, 95 percent of the gas was captured and converted, the study said.