"In a quiet patch of forest in Nova Scotia, a company is building a machine designed to help slow global warming by transforming Earth’s rivers and oceans into giant sponges that absorb carbon dioxide from the air.

When switched on later this year, the machine will grind up limestone inside a tall green silo and release the powder into the nearby West River Pictou, creating a chalky plume that should dissolve within minutes.

The effect could be potent, scientists say. Rivers contain carbon dioxide that is constantly escaping into the air, where it traps heat and warms the planet. But adding limestone converts some of that carbon dioxide into a stable molecule that instead stays underwater and washes into the sea, where it should remain trapped for thousands of years."

Brad Plumer and Raymond Zhong report for the New York Times with photographs by Greta Rybus September 23, 2024. [2]