As the earth keeps warming, many geoengineering solutions are being put forward, such as dropping iron in the ocean or desalinating massive quantities of seawater. A recent study looked at one idea – grinding up olivine and dumping it into the sea – and found it would be extremely inefficient.
Olivine is made of magnesium silicate. It is plentiful and easy to find. Crushing the olivine and distributing it across the world in the oceans would make the seas more alkaline and better able to absorb carbon dioxide from the atmosphere, thus cooling the earth.
The study, published in Environment Research Letters, calculated that it would take more than three billion tons of olivine dumped into the ocean every year to make up for just nine percent of humanity’s annual carbon emissions. An amount of CO2 equivalent to one-third of the sequestered carbon dioxide would be emitted when the rock was ground up, so the olivine would only make up for six percent of our annual carbon emissions.
Not only that, but the fleet of ships required to distribute the material would be prohibitive. The scientists estimated one hundred large ships, working full-time year-round to spread the olivine over the oceans, would be needed.
The high cost of the geoengineering scheme compared to the small payoff makes this an unlikely avenue to mitigate the effects of climate change.
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