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Other research groups also recently found that dissolving olivine in filtered and artificial seawater produced less of an increase in alkalinity than expected, the study noted. Still a recent preprinted paper found similar confounding results for other minerals thought to increase ocean alkalinity.
Meanwhile, several additional recent studies have cast doubt on another ocean-based approach: grow seaweed and sink It’s for carbon capture and storage.
Finding viable ways to reduce greenhouse gases will be vital in the coming decades. National Academy report in December on ocean carbon removal, noting that the world may need to suck in an additional 10 billion tons annually by mid-century to limit warming to 2 ˚C.
Increasing ocean alkalinity could theoretically remove tens of billions of tons per year, based on Ocean Visions research group. But the panel of the National Academies noted that it would require mining, grinding and transporting the rock on roughly the same scales, all of which would have significant environmental consequences.
New studies are yet to say definitively as to whether any of these approaches would be a viable way to help achieve those carbon removal goals.
But Michael Fuhr, one of the authors of the olivine study and a doctoral student at GEOMAR, says their findings suggest that the approach “has not been as easy as expected until now”. He adds that it may only work well in certain places where ocean chemistry is suitable. That could include areas of water that is low in salinity but rich in organic sediments, which would increase acidity.
Fuhr and others say that more laboratory experiments and field work will be needed to determine how well the method works in the real world, what ideal conditions are, or whether materials whether the other is more promising or not.
Maria-Elena Vorrath, a researcher at the Alfred Wegener Institute for Polar and Marine Research, said in an email that the study shows that the olivine process doesn’t work the way we had assumed. But she stressed that the mineral remains “one of the most enduring and promising methods nature has given us.”
