Geologists map rocks to soak CO...( To slow global warming scientist...)

To slow global warming, scientists are exploring ways to pull carbon dioxide from the air and safely lock it away. Trees already do this naturally through photosynthesis; now, in a new report, geologists have mapped large rock formations in the United States that can also absorb CO₂, which they say might be artificially harnessed to do the task at a vastly increased pace.

The report, by scientists at Columbia University's Earth Institute and the U.S. Geological Survey, shows 6,000 square miles of ultramafic rocks at or near the surface. Originating deep in the earth, these rocks contain minerals that react naturally with carbon dioxide to form solid minerals. Earth Institute scientists are experimenting with ways to speed this natural process, called mineral carbonation. If the technology takes off, geologic formations around the world could provide a vast sink for heat-trapping carbon dioxide released by humans.

Lead author Sam Krevor, a graduate student working through the Earth Institute's Lenfest Center for Sustainable Energy, says the United States' ultramafic rocks could be enough to stash more than 500 years of U.S. CO₂ production. Conveniently, most of them are clustered in strips along the east and west coasts--some near major cities including New York, Baltimore and San Francisco. "We're trying to show that anyone within a reasonable distance of these rock formations could use this process to sequester as much carbon dioxide as possible," said Krevor.

So-called carbon sequestration has become a hot area of research, but so far, most work has focused on storing liquid or gaseous CO₂ underground where there is room: in saline aquifers, depleted oil wells and porous coal seams that are not commercially viable. However, concern about leaks has scientists pursuing natural chemical reactions within the earth to turn the carbon back into a solid.

Ultramafic rocks
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