Adding volcanic rock dust to cropland could help the world reach a key carbon removal goal, a new study finds.
Rain absorbs carbon dioxide from the air as it falls, and it reacts with rocks on the ground to lock away that carbon. To speed this process, scientists have proposed spreading crushed volcanic rock on farmland. The new study is among the first to model the effect of this strategy, called enhanced rock weathering, at scale.
A simulation of more than 900 croplands spanning an area nearly the size of Australia suggests that enhanced rock weathering could scrub some 64 billion tons of carbon dioxide from the atmosphere by the end of this century.
The world currently produces around 37 billion tons of carbon dioxide yearly. To keep warming to 1.5 degrees C, the stated goal of the Paris Agreement, countries must not only slash emissions, but also remove at least 100 billion tons of carbon dioxide from the atmosphere.
Spreading rock dust across all of world’s croplands for the rest of this century, the study suggests, would draw down 215 billion tons of carbon dioxide. The findings were published in the journal Earth’s Future.
“There’s tremendous potential here,” study coauthor Noah Planavsky, a geochemist at Yale University, said in a statement. Enhanced rock weathering may even work better as the climate warms because weathering happens faster in hot and humid conditions. Rock dust could also help revive depleted farms and improve yields. And the low cost of crushed volcanic rock would potentially make this strategy attractive for farmers.