What eats Carbon dioxide ?

There is a type of rock with a voracious appetite for carbon dioxide.

 The rock is peridotite, which is one of the main rocks in the upper mantle, an area that provides a girth below the Earth’s crust. The rock occurs some 20km or more down, although in areas where plate tectonics have forced up some of the mantle, peridotite reaches the surface. This happens in part of the Omani desert which Peter Kelemen and Juerg Matter, both from Columbia University, New York, have studied for years. Geologists have long known that when peridotite is exposed to the air it can react quickly with carbon dioxide to form carbonates like limestone or marble.

In a research a team have shown that Omani peridotite can absorbs tens of thousands of tonnes of carbon dioxide a year, far more than anyone had thought. By drilling and fracturing the rock they believe they can start a process to increase the absorption rate by 100,000 times or more. They estimate this would allow the Omani outcrop, which extends down some 5km, alone to absorb some 4 billion tonnes of carbon dioxide a year, which is a substantial part of the annual 30 billion or so tonnes of the gas that humans send into the atmosphere, mostly by burning fossil fuels.

Peridotite can also be found at the surface in other parts of the world, including some Pacific islands, along the coasts of Greece and Croatia, and in smaller deposits in America. Nor is it the only rock with carbon-eating potential. The researchers are now looking at volcanic basalt in a new project in Iceland. 

The research has proved useful in depleting the Green house effect.