In a recent paper published in Nature, an international group of scientists from universities and research institutes in the United Kingdom, Belgium, and the United States embrace a geoengineering response to climate change: the spreading of crushed silicate rocks on cropland to remove carbon dioxide from the atmosphere.
As rain weathers rocks, it exposes minerals that naturally bind with carbon dioxide, transforming it into new chemicals. The research paper suggests we accelerate the process by grinding up millions of tons of rock each year and spreading the dust on farmers’ fields around the world. The researchers estimate such “enhanced weathering” could remove two billion tons of carbon dioxide from the atmosphere every year, approximately one-third of what the United States emits annually.
The costs of using enhanced weathering to capture carbon dioxide would be lower in tropical, developing countries with good weathering conditions: “(warm, seasonally wet weather), and low labor and energy costs.” In such locations the costs could be as low as $60 per ton of carbon dioxide stored—comparable to or lower than many of the carbon tax proposals proposed in various countries in recent years. In countries like the United States, the costs could top $176 per ton of carbon dioxide removed, equaling about $225 per American annually, the scientists estimate. Some of those costs would be offset by the rock dust improving soil health and helping to fertilize crops, which would reduce the amount of other fertilizers farmers have to apply to their fields and would improve crop yields, which should lower food costs.
James Hansen, among the most prominent climate alarmists, has embraced enhanced weathering as a response to climate change. Hanson is a coauthor of the paper. In an e-mail, Hansen told Grist he endorses enhanced weathering because it can store carbon dioxide for thousands of years without continuous active management: you just spread the rock dust and let weathering do the rest. “Hansen said other approaches, ‘such as reforestation, are important, but require management to assure that the carbon sink is maintained,’” Grist reports.
OCTOBER 9, 2020