The simple act of spreading rock dust on farms is an overlooked solution to helping capture carbon dioxide.
Sprinkling rock dust - an abundant byproduct of mining - on farmland could capture 45 percent of the carbon dioxide required to help the UK meet its 2050 net-zero targets. This new figure from a recent study adds to a growing body of evidence looking at the power of minerals to draw down carbon, while also replenishing agricultural soils.
Most people think that trees and bogs are the key absorbers of CO2, but rocks are also some of our planet’s greatest carbon sinks. This capture occurs through a process called chemical weathering, whereby atmospheric CO2 gets dissolved in raindrops, forming carbonic acid, which reacts with the rock minerals and causes them to break down and ‘weather’. During that process, carbon also changes form and gets locked into the sediment as bicarbonate: this effectively strips it from the atmosphere and keeps it circulating in terrestrial and ocean systems for long periods of time.
Chemical weathering occurs on naturally slow timescales but we can accelerate this process by crushing them, which exposes minerals and creates a larger surface area for weathering to occur and therefore for minerals to absorb CO2. This is the idea behind rock dust.
Sprinkling rock dust on farmland anywhere is now proven as a good idea but the new research paper focuses in on the UK, where they discover the unrecognized potential for this approach to meet the country’s net-zero goals.
Specifically, the researchers looked at basalt, a widely-available mining byproduct that contains rapidly-weathering minerals. Their model also incorporated the emissions costs of mining and then spreading this powdered rock over fields.
Despite this, the potential of rock dust to offset the country’s emissions was huge: by 2050, it could be removing up to 30 million tons of CO2 from the atmosphere each year, capturing almost half of the emissions the UK needs to vanquish from its atmosphere, if it hopes to reach its 2050 net zero targets. Let's hope that farmers think that this is a great idea too!