Researchers are taking a look at an often underestimated technique for carbon dioxide removal. A new study shows adding rock dust to UK agricultural soils – a process known as enhanced weathering could absorb up to 45% of the atmospheric carbon dioxide needed for the country to reach its net zero target by 2050.
According to the research led by scientists at the University of Sheffield, enhanced weathering has a carbon removal potential of 6-30 million tons of carbon dioxide annually by 2050.
“It’s got overlooked potential to help with the UK net-zero-by-2050 commitment… And it has a number of co-benefits that industrial processes don’t have and it’s highly [cost] competitive,” said David Beerling from the University of Sheffield.
Adding rock dust to agricultural lands speeds up a natural process that locks in carbon dioxide in the soil. If applied to croplands globally, rock dust could theoretically help suck an estimated 2 to 4 billion tons of carbon dioxide from the air every year.
That is between 34% and 68% of global greenhouse gas emissions produced by agriculture annually. According to IPCC, rocks naturally remove 1 gigaton of CO2 a year from the atmosphere.
The findings of the Beerling’s team show that the technique is more expensive than tree planting, but is about half the cost of the direct air capture method. The deployment is also straightforward as the approach uses existing infrastructure.
Spreading rock dust in the soil also acts as a fertilizer, boosting crop yields which is an additional benefit of the approach. Some other side effects could include lowering the emissions of nitrous oxide, reversing soil acidification that limits yields, and reducing demands for imported fertilizers.
The study also highlights that societal acceptance for enhanced weathering is required from national politics through to local community and farm scales. Additionally, mining operations for producing the basalt rock dust could bring in additional employment.
This new study provides much-needed detail on the carbon removal potential of adding rock dust to the soil. It is often overlooked natural carbon sink as more attention is given to technological solutions like carbon capture and storage, however, it is worth taking a closer look into more affordable approaches.