Thursday 9 July 2020
Adding rock dust to crops ‘could trap two billion tonnes of carbon dioxide every year’
Adding crushed rock dust to crops could help trap two billion tonnes of carbon dioxide from the air per year and help meet key global climate targets
A new study led by the University of Sheffield suggests spreading powdered basalt on fields can boost the soil’s ability to extract greenhouse gases from the air - known as enhanced rock weathering, the technique of spreading the natural volcanic rock would be relatively straightforward to implement for farmers, many of whom already add agricultural lime to their soils.
Researchers highlight limiting global temperature increases to below 2C above pre-industrial levels and reaching net zero by 2050 will not only require "drastic cuts in emissions", but also the active removal of between two and 10 billion tonnes of carbon dioxide from the atmosphere each year.
They say China, the United States and India have the potential to remove approximately one billion tonnes of the greenhouse gas annually, at a cost comparable to that of other proposed carbon dioxide removal strategies, and note Indonesia and Brazil also have relatively high carbon dioxide removal potential due to the presence of "extensive" agricultural lands in these nations.
The research adds silicate rock dust left over from the mining industry could be used in this process and calls on governments around the world to start developing stockpiles.
Professor James Hansen, a partner in the study and Director of the Climate Science, Awareness and Solutions Program at Columbia University’s Earth Institute, said: “We have passed the safe level of greenhouse gases. Cutting fossil fuel emissions is crucial, but we must also extract atmospheric carbon dioxide with safe, secure and scalable carbon dioxide removal strategies to bend the global carbon dioxide curve and limit future climate change.
"The advantage of carbon dioxide removal with crushed silicate rocks is that it could restore deteriorating top-soils, which underpin food security for billions of people, thereby incentivising deployment."
