James Temple writes:

On a scorching day this August, Caleb Woodall wielded his shovel like a spear, stabbing it into the hardened crust of an asbestos-filled pit near Coalinga, California.

Woodall, a graduate student at Worcester Polytechnic Institute in Massachusetts, was digging out samples from an asbestos mine that’s been shuttered since 1980, a Superfund site on the highest peak in the state’s Diablo Range. He extracted pounds of the material from several locations across San Benito Mountain, shoveled them into Ziploc bags, and shipped them to a pair of labs for analysis.

He and his colleagues are trying to determine the makeup and structure of the materials pulled from the pits, and to answer two critical questions: How much carbon dioxide do they contain—and how much more could they store?

The vast surface area of certain types of fibrous asbestos, a class of carcinogenic compounds once heavily used in heat-resistant building materials, makes them particularly good at grabbing hold of the carbon dioxide molecules dissolved in rainwater or floating through the air.

That includes the most common form of asbestos, chrysotile, a serpentine mineral laced throughout the mountain (serpentine is California’s state rock). The reaction with carbon dioxide mainly produces magnesium carbonate minerals like magnesite, a stable material that could lock away the greenhouse gas for millennia.

Woodall and his advisor Jennifer Wilcox, a carbon removal researcher, are among a growing number of scientists exploring ways to accelerate these otherwise slow reactions in hopes of using mining waste to fight climate change. It’s a handy carbon-capturing trick that may also work with the calcium- and magnesium-rich by-products of nickel, copper, diamond, and platinum mining.

The initial hope is to offset the ample carbon emissions from mining itself using these minerals already extracted in the process. But the real hope is that this early work allows them to figure out how to effectively and affordably dig up minerals, potentially including asbestos, specifically for the purpose of drawing down vast amounts of greenhouse gas from the atmosphere.

“Decarbonizing mines in the next decade is just helping us to build confidence and know-how to actually mine for the purpose of negative emissions,” says Gregory Dipple, a professor at the University of British Columbia and one of the leading researchers in this emerging field.

The UN’s climate panel found that any scenario that doesn’t warm the planet by more than 1.5 ˚C will require nearly eliminating emissions by midcentury, as well as removing 100 billion to 1 trillion metric tons of carbon dioxide from the air this century. Keeping warming below 2˚ C could necessitate sucking out 10 billion tons a year by 2050 and 20 billion annually by 2100, a study by the National Academies found.

That’s such a giant amount that we’ll almost certainly need to use a variety of methods to get anywhere close, including planting trees and increasing carbon uptake in agricultural soils. The particular promise of using minerals to pull down carbon dioxide is that it can be done on a massive scale—and would effectively store it away forever. [Continue reading…]