Guest essay by Eric Worrall
A new study suggests spreading crushed volcanic rock across the world’s farmland would absorb enough CO2 to curb global warming, so long as a cost effective means to crush all that rock can be discovered.
How Crushed Volcanic Rock in Farm Soil Could Help Slow Global Warming — and Boost Crops
A new study explores how planet-warming carbon dioxide could be absorbed using ‘enhanced rock weathering,’ a natural process sped up to fight climate change.
BY GEORGINA GUSTIN
Pulverizing volcanic rock and spreading the dust like fertilizer on farm soils could suck billions of tons of carbon from the atmosphere and boost crop yields on a warming planet with a growing population.
In a paper published this week in the scientific journal Nature Plants, an international team of researchers lays out the prospects for “enhanced rock weathering”—a process that uses pulverized silicate rocks, like basalt, to speed the ability of minerals to store carbon in soil.
This could happen fairly quickly. “Conceivably, roll-out could take place within a decade or two,” said David Beerling, director of the Leverhulme Centre for Climate Change Mitigation at the University of Sheffield and the lead author of the study.
The abstract of the study;
Farming with crops and rocks to address global climate, food and soil security
David J. Beerling, Jonathan R. Leake, Stephen P. Long, Julie D. Scholes, Jurriaan Ton, Paul N. Nelson, Michael Bird, Euripides Kantzas, Lyla L. Taylor, Binoy Sarkar, Mike Kelland, Evan DeLucia, Ilsa Kantola, Christoph Müller, Greg Rau & James Hansen
The magnitude of future climate change could be moderated by immediately reducing the amount of CO2 entering the atmosphere as a result of energy generation and by adopting strategies that actively remove CO2 from it. Biogeochemical improvement of soils by adding crushed, fast-reacting silicate rocks to croplands is one such CO2-removal strategy. This approach has the potential to improve crop production, increase protection from pests and diseases, and restore soil fertility and structure. Managed croplands worldwide are already equipped for frequent rock dust additions to soils, making rapid adoption at scale feasible, and the potential benefits could generate financial incentives for widespread adoption in the agricultural sector. However, there are still obstacles to be surmounted. Audited field-scale assessments of the efficacy of CO2 capture are urgently required together with detailed environmental monitoring. A cost-effective way to meet the rock requirements for CO2 removal must be found, possibly involving the recycling of silicate waste materials. Finally, issues of public perception, trust and acceptance must also be addressed.
Read more (paywalled): https://www.nature.com/articles/s41477-018-0108-y
In my opinion this is one of the most terrifying geo-engineering schemes I’ve ever seen.
Leaving aside the hopefully insurmountable issue of finding affordable means to crush and distribute all that volcanic rock, imagine the consequences if the scheme went too far, if CO2 levels undershot the desired target range.
In the last ice age, CO2 may have dropped as low as 180ppm. Life on Earth was almost extinguished by lack of CO2.
Assuming the scheme worked, it wouldn’t take much of an undershoot to bring life on Earth back to the brink of CO2 starvation. Even if the undershoot didn’t kill everything, it would almost certainly trigger widespread famine as global agriculture collapsed for lack of CO2 to fertilise the crops.
Higher CO2 levels are nowhere near as hazardous as lower CO2 levels. If CO2 climbs by 200ppm, or even 1000ppm, so what? Life would still flourish across most of the Earth, just as life flourished in past epochs when CO2 levels were high. But if CO2 levels dropped for whatever reason, by 200ppm or more, the world might end.