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Rock dust that spreads over the planet's agricultural fields may be a climate solution with the potential to remove up to two billion tons of carbon dioxide (CO2) from the atmosphere, according to British researchers.
That's more than the global aviation and shipping industries combined, or about half of Europe's current emissions. Research published last week in the journal Nature looks at how the technique could be used in different countries, with optimism about how some of the world's highest CO2 emitters, including China, India and Brazil, benefit the most in terms of removal. of CO2.
The team of scientists, led by David Beerling of the Leverhulme Center for Climate Change Mitigation at the University of Sheffield, also included experts from institutions in the United States and Belgium, including world climate leader James Hansen of the Earth Institute. at Columbia University. They explain how rock weathering, as the technique is known, could also provide a circular economy use for mining by-products and recycled building materials.
The benefits come when farmers apply finely crushed basalt, which is naturally found in volcanic rock, in the fields. Basalt improves the ability of soils to extract CO2 from the air and sequester it in the soil. Beerling and the researchers say it is easy for farmers to do and would improve both soils and their income.
Basalt is made of lava that cools quickly and is compatible with existing standards for organic fertilizers. It dissolves in the soil, initiating a chemical reaction that increases the capacity to capture and store CO2. At the same time, it is safe for crops and provides at least six nutrients, potassium, phosphorus and calcium among them. It also changes the pH of the soil, making it less acidic, and that can even benefit increasingly acidic bodies of water if it gets into runoff from farmland.
Some recycled silicate products from the mining industry and iron and steel manufacturing, as well as waste cement from construction projects, could be processed and used in the same way. That's beneficial for both reducing climate impacts and creating new revenue streams, and these researchers are calling on global governments to develop rock dust resources and access to them.
There is a lot of work to be done before scientists are confident about how basalt dust will behave and what the broader impacts will be. That is why there is a 10-year project in Leverhulme to study the implications and field trials through the University of Illinois Urbana-Champaign in the USA, as well as at sites in Australia and Borneo, but at the same time scientists agree that there is no time to waste.
"Scalable carbon dioxide reduction strategies are urgently required to support existing land uses to combat climate change, along with deep and sustained emissions cuts," says Beerling. "Diffusion of rock dust on farmland is a direct and practical approach to CO2 reduction with the potential to boost soil health and food production."
His colleague Hansen, a former director of NASA's Goddard Institute for Space Studies who has lobbied for climate action for decades, echoed Beerling's hopes of rolling out rock weathering techniques.
"We have exceeded the safe level of greenhouse gases," Hansen said. "Reducing fossil fuel emissions is crucial, but we must also extract atmospheric CO2 with safe and scalable carbon dioxide removal strategies to bend the global CO2 curve and limit future climate change."