A bold plan to protect the planet turns carbon dioxide into stone

The tired and crumbling peak of Mount Hajar was slowly crumbling down like a plate of rotting flesh. Thin traces of decay were everywhere. Groundwater sometimes contains bubbles of flammable hydrogen gas. Water from natural springs is often soggy with minerals. This water leaves a stretch of frozen white crystals as it flows on the ground. Only some plant species can grow in such foreign lands.

Here in the desert state of Oman, east of Saudi Arabia, mountains harbor exotic minerals not usually found on Earth's surface. They form tens of kilometers (miles) deep - deeper than humans have ever dug for oil or gold. Now exposed to air and water at the Earth's surface, this mineral is chemically unstable.

It flows into rock crevices when it rains, carrying gas from the air. Water and gases react with rocks to form new, colored minerals. The jagged veins of this black, white, and blue-green gem are pushed deeper and deeper into the bedrock. Like a slow but powerful finger, the minerals widen the cracks and tear the rock.

Peter Kelemen believes these crumbling rocks can help humans solve a central problem: climate change.

He noted that the white veins of carbonate in rainwater form as carbon dioxide (CO2) bonded to magnesium and calcium atoms in rock. In other words, this new mineral captures the same gases that humans give off when they burn fossil fuels. These are the same greenhouse gases that warm our planet.

This unusual rock is commonly found in an area of ​​Oman the size of Maryland. They naturally petrify 50,000 to 100,000 tonnes of CO2 per year, Kelemen said. That's a meager amount compared to the 30 billion tons of CO2 humans emit each year. But Kelemen and his colleagues believe that these rocks could one day harden to a billion tons of CO2 per year. Other rock formations scattered around the world can bind 10 to 20 billion tons of CO2 every year. "You're looking at something that has the potential to affect humanity's global carbon budget," he told me one afternoon in Oman.