Rocks could save the world (Yes, rocks) - Elise Cutts

The Canary Islands are home to Mount Teide,

one of the world’s largest active volcanoes.

Capable of spewing tens of millions of cubic meters of lava in a single eruption,

Teide’s destructive power is nothing to scoff at.

But there may be a way to use the basalt rock inside Teide to save humanity.

That’s right— blowing up this volcano could offset Earth’s emissions

for the foreseeable future.

Obviously, destroying an ancient volcano is not a good idea.

The ecological fallout would be catastrophic and unpredictable.

But even if we harvested some of that basalt,

could we really use it to stop climate change?

This theoretical scheme is a dramatic way to enhance

one of Earth’s least dramatic natural processes:

rock weathering.

Rock weathering occurs whenever it rains.

As falling rainwater mixes with atmospheric carbon dioxide,

it becomes a weak acid that can eat away at minerals called silicates.

And since silicates are in over 90% of Earth’s exposed rock,

this happens pretty much anywhere rain hits stone.

As this acid reacts with the stone,

this dissolved carbon dioxide in the rainwater

turns into a new form called bicarbonate,

which trickles downstream alongside the rain to the ocean.

Here marine critters use it to create structures like shells.

And when they die, those shells sink to the seafloor,

trapping that carbon dioxide in the ocean for millennia.

This process has a massive impact on Earth's climate.

When it's warm and wet, the rock weathering speeds up,

tempering greenhouse warming.

When it's cold and dry, the process slows down,

building up atmospheric carbon dioxide.

But these effects take time—

natural rock weathering balances Earth’s climate over millions of years.

Thankfully, experts working to sequester atmospheric carbon

have plans to speed things up.

Two major factors determine the pace of this process:

the types of rock exposed to weather and the amount of rock that’s exposed.

Silicates that form at higher temperatures tend to weather faster

due to their chemical composition.

These rocks include those from Earth’s deep mantle

and volcanic rocks like basalt.

But piled up in a mountain, not very much rock is exposed.

So, some climate experts believe we should harvest that fast-weathering rock,

crush it, and spread it out to weather more rock in less time.

This sped up process is called enhanced rock weathering,

and it’s among the most practical plans we have for drawing down carbon.

Rather than needing to invent all-new technology,

we can rely on existing systems for mining and processing rock.

And since agricultural communities have long known that volcanic rocks and soils

can improve crop yield,

farmlands could be the perfect dispersal sites.

But for this approach to have impact, it needs to be deployed globally.

And even without demolishing any volcanoes,

large-scale solutions always come with large-scale problems.

First off, rock weathering— enhanced or otherwise—

runs through the entire global water cycle.

Since this open system has more variables than we could ever account for,

it’s difficult to measure enhanced rock weathering’s precise impact.

Second, despite existing mining technology,

it would be a massive ecological and engineering challenge

to quarry, crush, transport, and spread this much rock.

The logistical difficulty of distributing this material

would be similarly demanding.

And unless the energy used for both tasks came from mostly clean sources,

it would undermine the project's net carbon impact.

Finally, any endeavor that impacts Earth’s natural systems at this scale

might have unpredictable side effects.

For example, quarried rocks might contain dangerous heavy metals

or other unknown elements.

But these challenges aren’t reasons to abandon enhanced rock weathering—

they’re just the first obstacles to implementing this promising strategy.

Simulations suggest a global enhanced rock weathering program

that spreads 10 tons of basalt dust on every hectare of global farmland

could sequester over 200 gigatons of CO2 over a 75-year period.

Those are remarkable figures for an approach this cheap and practical,

and they prove you don't need to blow up a mountain to have big impact.