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    Review of 'An Assessment of the Potential Value for Climate Remediation of Ocean Calcifiers in Sequestration of Atmospheric Carbon'

    An Assessment of the Potential Value for Climate Remediation of Ocean Calcifiers in Sequestration of Atmospheric CarbonCrossref
    The review proposed by Moore and colleagues is timely and delves into the arguments in detail
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    An Assessment of the Potential Value for Climate Remediation of Ocean Calcifiers in Sequestration of Atmospheric Carbon

    Today’s marine calcifiers (coccolithophore algae, Foraminifera [protists], Mollusca, Crustacea, Anthozoa [corals], Echinodermata) remove carbon dioxide (CO 2 ) from the atmosphere, converting it into solid calcium carbonate (CaCO 3 ) which is stable for geological periods of time. These organisms could serve as a biotechnological carbon capture and storage mechanism to control climate change. Two criticisms made about this are: (i) ocean acidification has allegedly been shown to cause reduced shell formation in calcifiers; (ii) the calcification reaction that precipitates CaCO 3 crystals into the shells is alleged to return CO 2 to the atmosphere. In this review we assess the evidence concerning such criticisms and find reasons to doubt both. Experiments showing that ocean acidification is damaging to calcifiers have all used experimental pH levels that are not projected to be reached in the oceans until the next century or later; today’s oceans, despite recent changes, are alkaline in pH. Claiming precipitation of CaCO 3 during calcification as a net source of CO 2 to the atmosphere is an oversimplification of ocean chemistry that is true only in open water environments. Living calcifiers do not carry out the calcification reaction in an open water environment in equilibrium with the atmosphere. The chemistry that we know as life takes place on the surfaces of enzymatic polypeptides, within organelles that have phospholipid membranes, contained in a cell enclosed within another phospholipid bilayer membrane specifically to isolate the chemistry of life from the open water environment. Ignoring what is known about the biology, physiology, and molecular cell biology of living organisms, calcifiers of all types especially, leads to erroneous conclusions and deficient advice about the potential for biotechnology to contribute to atmosphere remediation. We conclude that the world’s aquaculture industries already operate the biotechnology that, with massive and immediate global expansion, can contribute to sustainably controlling atmospheric CO 2 levels at reasonable cost and with several positive benefits in addition to carbon sequestration.

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      This work has been published open access under Creative Commons Attribution License CC BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Conditions, terms of use and publishing policy can be found at www.scienceopen.com.

      Earth & Environmental sciences,Life sciences
      biotechnology,carbon sequestration,carbonate chemistry,aquaculture,carbonate biology,remediation.,climate change
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      Review text

      The review proposed by Moore and colleagues is timely and thoroughly delves into the arguments. After introducing the problem of recognising the carbon sink role played by the shells of bivalve molluscs and other calcifying organisms, it addresses and argues, point by point, the criticisms raised, providing appropriate bibliographic references and examples. The authors range from describing the chemistry in open waters vs what happens in coastal marine contexts, where the farms are located, describing the processes of calcium carbonate formation. Then they describe aspects such as the physiological mechanisms that regulate the formation of calcium carbonate and the release of CO2 resulting from the process, which does not take place in an aquatic environment but within the organism and its membranes, and ends by describing how multiple disciplines and tools (e.g. LCA) support their arguments. A minor shortcoming that may be noted is that the work perhaps fails to mention the importance of the dependence of environmental conditions (pH, CO2 partial pressure, salinity and temperature) for the conversion efficiency of hydrogen carbonate and calcium ion to calcium carbonate. However, overall, the work is really significant for the fervent scientific debate on this topic. 



      Thank you for your supportive review. I can easily incorporate comments about dependence on environmental conditions as you suggest. I will delay producing a revised manuscript until we have the necessary SECOND review, so that the revision incorporates responses to both reviews.

      Best regards, David Moore

      2022-08-22 08:38 UTC

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