“CO 2 drawdown strategies that can scale up and are compatible with existing land uses are urgently required to combat climate change, alongside deep emissions cuts,” said Prof David Beerling, of the University of Sheffield, a lead author of the study. The cost depends on local labour rates and varies from $80 per tonne in India to $160 in the US, and is in line with the $100-150 carbon price forecast by the World Bank for 2050, the date by which emissions must reach net zero to avoid catastrophic climate breakdown. The analysis, published in the journal Nature, estimates that treating about half of farmland could capture 2bn tonnes of CO 2 each year, equivalent to the combined emissions of Germany and Japan. The researchers also found that the world’s biggest polluters, China, the US and India, have the greatest potential for ERW, as they have large areas of cropland and relatively warm weather, which speeds up the chemical reactions. First, many farmers already add limestone dust to soils to reduce acidification, and adding other rock dust improves fertility and crop yields, meaning application could be routine and desirable.īasalt is the best rock for capturing CO 2, and many mines already produce dust as a byproduct, so stockpiles already exist.
The rock dust approach, called enhanced rock weathering (ERW), has several advantages, the researchers say. But climate scientists also agree that, in addition, massive amounts of CO 2 need to be removed from the air to meet the Paris agreement goals of keeping global temperature rise below 2C. The researchers are clear that cutting the fossil fuel burning that releases CO 2 is the most important action needed to tackle the climate emergency.
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