STOP PRESS: It appears that the main proposition of this website—that the augmented cultivation of bivalve molluscs and the proper disposal of their shells would provide a means of removing large amounts of CO2 from the atmosphere—is not valid! When CaCO3 is removed from seawater, its pH shifts toward the acidic, and the CO2 concentration and pCO2 of the water increases, leading to increased concentrations of CO2 in the atmosphere. A diagram showing the effects of various ocean biogeochemistry processes on CO2 and pH can be found in Figure 1.1.3 of CO2 in Seawater: Equilibrium, Kinetics, Isotopes, Richard E. Zeebe and Dieter Wolf-Gladrow, Amsterdam: Elsevier, 2001.
This website is about the concept of shellfish sequestration and how it may remove substantial quantities of carbon dioxide from the atmosphere. In this proposal, the cultivation of mussels and other bivalve molluscs would be expanded around the world and the shells of those molluscs would be disposed of in a manner that would ensure long term sequestration of the CO2 that is embodied in them.
Given that there is rapid equilibration of CO2 concentrations
between the atmosphere and surface layers of the sea, shellfish sequestration
should have the effect of reducing concentrations of CO2 in the
Potential problems that are considered include the possibility that the availability of calcium might be a limiting factor, that the growth of shellfish might be stalled by acidification of the oceans, that there might be an unacceptable impact on the environment, that there might be a net release of CO2 into the atmosphere, and that shellfish farmers have to contend with problems such as disease and predation. It appears that none of these potential problems are showstoppers that should inhibit further investigation and development.
Using shellfish sequestration, it appears to be feasible to remove from circulation
as much as 21 gigatonnes of CO2 each year, possibly more. At that
rate, it would be possible, within one human lifetime, to take as much of CO2
out of circulation as has been released into the atmosphere since the beginning
of the industrial revolution by the burning of fossil fuels and the production
of cement. Even at a fifth of that rate, shellfish sequestration could make a substantial
contribution to the stabilisation of the earth’s climate.
Costs would be substantial but affordable. There would be several potential spin-off benefits including a reduction in acidification of the oceans or its rate of increase, the creation of jobs and earnings for many people around the world, the creation of a substantial, protein-rich addition to world food supplies, providing incentives to control pollution and, by excluding industrial-scale fishing from large areas of the sea, the creation of new marine nature reserves.
Much more detail may be found in the draft of an article, below. But, as noted above, it appears that the central proposition is not valid!
We did have some doubts that the mechanism would work as we anticipated, and we did seek advice from someone with specialist knowledge of marine chemistry. But it turned out that the advice we were given was, very likely, wrong!
Shellfish sequestration: the augmented cultivation of molluscs, and the preservation of their shells, as a means of sequestering carbon dioxide (PDF, 401 KB).