ocean Olivine

German researchers have concluded that the idea of “seeding” oceans to absorb more CO2 from the atmosphere is too inefficient a process to stop climate change from the ruining the world.

The research, published today in the journal Environmental Research Letters, analyses the idea of dispersing ground- up olivine into oceans to soak up CO2 and create plankton, which would then sink to the bottom of oceans along with the CO2.

Olivine is an abundant group of magnesium-silicate minerals found in the Earth’s upper mantle. The seeding of oceans with olivine is often discussed as a potential “quick fix” solution to climate change.

However the results of computer modelling conducted by researchers from the Alfred Wegener Insitute for Polar and Marine Research in Bremerhaven, Germany, indicate that the scale of the industrial processing and distribution necessary to implement the idea would make olivine ineffective at reducing atmospheric CO2 levels.

The olivine would have to be ground down to sizes of around one micrometre in order to be dissolved in oceans. This grinding process would consume energy and therefore emit varying amounts of CO2, depending on the sort of power plants used to provide the energy.

Lead author of the study, Peter Köhler, said: “Our estimates on the energy costs of grinding olivine suggest that with present day technology, around 30% of the CO2 taken out of the atmosphere and absorbed by the oceans would be re-emitted by the grinding process.”

Six different scenarios were analysed by the researchers. The results showed that if three gigatonnes of olivine were deposited into oceans each year, only nine per cent of present day man-made CO2 emissions would be absorbed.

Furthermore, if olivine was used to counteract the problem of ocean acidification, which is caused by CO2 emissions and continues to have a profound effect on marine life, around 40 gigatonnes would be needed annually.

Köhler said: “If this method of geoengineering was deployed, we would need an industry the size of the coal industry to obtain the necessary amounts of olivine. To distribute this, we estimate that 100 dedicated large ships with a commitment to distribute one gigatonne of olivine per year would be needed.

“Taking all our conclusions together – mainly the energy costs of the processing and the projected potential impact on marine biology – we assess this approach as rather inefficient. It certainly is not a simple solution against the global warming problem.”


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