Rock dusting on farms could cool the climate, so let’s try it

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By Olive Heffernan

On the menu of geoengineering options, one has always stood out as a saner choice: enhanced weathering. No need to deploy giant mirrors in space to deflect sunlight or to risk food riots by converting crops to fuel. Just scatter crushed rock far and wide.

It sounds simple: rock mops up carbon dioxide – it’s a slow but significant part of the carbon cycle – so if we speed up natural weathering we could get enough of this greenhouse gas out of the atmosphere to dampen climate change.

Ordinarily, common silicate minerals react slowly …