The Science We Need to Assess Marine Carbon Dioxide Removal

https://eos.org/opinions/the-science-we-need-to-assess-marine-carbon-dioxide-removal

By Jaime B. Palter,  Jessica Cross,  Matthew C. Long,  Patrick A. Rafter and  Clare E. Reimers, Eos/AGU. Excerpt: As companies begin selling credits for marine carbon dioxide removal in largely unregulated marketplaces, scientists must develop standards for assessing the effectiveness of removal methods. ...Three categories of mCDR [marine CO₂ removal] approaches—ocean iron fertilization, artificial upwelling, and seaweed cultivation—aim to stimulate primary productivity at the ocean’s surface with the expectation that some of the additional biomass produced will sink into and remain in the deep ocean. In contrast, ocean alkalinity enhancement (OAE) involves intentionally dispersing alkaline materials such as lime on the ocean’s surface to shift the chemical equilibrium of the seawater carbon system and thereby increase uptake of atmospheric CO₂. Still another approach proposes to remove CO₂ directly from seawater through electrochemical reactions and then store it underground. ...At least half a dozen companies involved in mCDR, and more that are rapidly entering the space, are starting to market CO₂ removal services to potential buyers interested in purchasing credits to offset carbon emissions. To support verification of these services, there is an urgent need for methods that rigorously quantify net carbon removal rates and storage durability of different mCDR approaches....