A 3-D global ocean model used previously to determine natural oceanic uptake of anthropogenic CO2 is used here to evaluate another proposed strategy for mitigation of rising atmospheric CO2. As a reference, this study bases itself on previous efforts with the same model to evaluate the potential of Fe fertilization as a means to enhance oceanic CO2 uptake. From that base, we test the feasibility of slowing the rise in atmospheric CO2 by enhancing growth of seaweed, a proposal resurrected from previous efforts considering it as a means to grow marine biomass as fuel for energy production. To determine its maximum potential, logistical and financial constraints are ignored. An enhanced growth of 1 GT C yr−1 is prescribed to be evenly distributed over a large ocean area such as the equatorial band from 18°S to 18°N and the northern and southern subtropics from 18° to 49° latitude. Results from these simulations clearly demonstrate that the CO2 invasion from the atmosphere is substantially less than C removed from the surface via enhanced growth. When enhanced growth is supported only by naturally available nutrients, the enhancement to the air to sea CO2 flux averages 0.2 GT C yr−1 for the first 100 yr. When nutrients are supplied artificially to support the enhanced growth, the mean enhanced air to sea flux is more (for the first 100 yr it averages 0.72 GT C yr−1 when all enhanced growth is harvested but only 0.44 GT C yr−1 without harvesting); however, generating enhanced marine growth at 1 GT C yr−1 requires an unreasonably large supply of nutrient—close to the world's current rate of fertilizer production for P and substantially more than that for N. Less nutrient is needed if the enhanced algal growth is not harvested and thus respired, but respiration increases demand for oxygen so that significant anoxia develops. We conclude that growth of macroalgae is an inefficient mechanism for sequestering anthropogenic CO2 and that the use of macroalgae as an additional fuel source will actually result in a net transfer of CO2 from ocean to atmosphere; however, there would be a reduction in the atmospheric CO2 increase rate if macroalgae were used as a partial replacement for fossil fuel.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Price excludes VAT (USA)
Tax calculation will be finalised during checkout.
Adey, W. H., 1984. Biomass from the sea: a new approach to obtain optimal solar energy conversion in the ocean, Bioenergy council, Washington, D.C., 21 pp.
Bacastow, R., and E. Maier-Reimer, 1990. Ocean-circulation model of the carbon cycle, Climate Dynamics, 4, 95–125.
Bacastow, R., and G. R. Stegen, 1991. Proc. OCEANS 91, 3, 1654–1657, Honolulu.
Bird, K. T., 1987. Cost analyses of energy from marine biomass, in K. T. Bird and P. H. Benson (eds.), Seaweed Cultivation for renewable resources, Elsevier, New York, pp. 327–350.
Bryan, K. 1969. A numerical method for the study of the circulation of the world ocean, J. Comput. Phys., 4, 347–376.
FAO, 1988. FAO Fertilizer Yearbook, FAO Statistics Series No. 89, Food and Agriculture Organization of the United Nations, Rome.
Glen, E. P., K. J. Kent, T. L. Thompson, and R. J. Frye, 1991, Seaweeds and halophytes to remove carbon from the atmosphere, Electric Power Res. Inst., ER/EN-7177, Palo Alto, CA, 71 pp.
Hellerman, S. and M. Rosenstein, 1983. Normal monthly wind stress over the world ocean with error estimates, J. Phys. Oceanogr., 13, 1093–1104.
Houghton, J. T., G. J. Jenkins, and J. J. Ephraums, 1990. Climate Change, The IPCC Scientific Assessment, Cambridge U. Press, Cambridge, 365 pp.
Joos, F., J. L. Sarmiento, and U. Siegenthaler, 1991a. Estimates of the effect of Southern Ocean iron fertilization on atmospheric CO2 concentrations, Nature, 349, 772–775.
Joos, F., U. Siegenthaler, and J. L. Sarmiento, 1991b. Possible effects of iron fertilization in the Southern Ocean on atmospheric CO2 concentrations, Global Biogeochem. Cycles, 5, 135–150.
Levitus, S., 1982. Climatological atlas of the World Ocean, NOAA Prof, Pap. 13, U.S. GPO., Washington, D.C., 173 pp.
Maier-Reimer, E., 1991a. in M. Latif (ed.), Strategies for future climate research, Max-Planck-Institut fur meteorologie, Hamburg, pp. 319–339.
Maier-Reimer, E., 1991b, private communication.
Maier-Reimer, E., and K. Hasselmann, 1987. Transport and storage of CO2 in the ocean — an inorganic ocean-circulation cycle model, Climate Dynamics, 2, 63–90.
Marchetti, C., 1977. On geoengineering and the CO2 problem, Climatic change, 1, 59–68.
Martin, J. H., 1990. Glacial-interglacial CO2 change: the iron hypothesis, Paleoceanogr., 5, 1–13.
Martin, J. H., S. E. Fitzwater, and R. M. Gordon, 1990. Iron deficiency limits phytoplankton growth in Antarctic waters, Global Biogeochem. Cycles, 4, 5–12.
McKay, L. B., 1983. Seaweed raft and farm design in the United States and China, NTIS Report PB84-163864, NOAA, Sea Grant, Rockville, MD, 108 pp.
Najjar, R. G., 1990. Simulations of the phosphorus and oxygen cycles in the world ocean using a general circulation model, Ph.D. thesis, Princeton Univ., 190 pp.
North, W, 1987, Ocean farming of Macrocyctis, the problems and non-problems, in K. T. Bird and P. H. Benson (eds.), Seaweed cultivation for renewable resources, Elsevier, New York, pp. 39–68.
Oeschger, H., U. Siegenthaler, U. Schotterer, and A. Gugelmann, 1975. A box diffusion model to study the carbon dioxide exchange in nature, Tellus, 27, 168–192.
Oltman, R.E., 1968, Reconnaissance investigations of the discharge and water quality of the Amazon River, Geol. Surv. Circ. U.S., 552, 16pp.
Peng, T.-H., and W. S. Broecker, 1991a. Dynamic limitations on the Antarctic iron fertilization strategy, Nature, 349, 227–229.
Peng, T.-H., and W. S. Broecker, 1991b. Factors limiting the reduction of atmospheric CO2 by iron fertilization, Limnol. Oceanogr., in press.
Ritschard, R. 1992, Marine Algae as a CO2 sink, Water, Air, and Soil Pollution, this issue.
Ryther, J. H., 1984, Technology for the commercial production of macroalgae, in M. Z. Lowenstein (ed.), Energy applications of biomass, Elsevier, London, pp. 39–68.
Sarmiento, J. L., and J. C. Orr, 1991. Three dimensional ocean model simulations of the impact of Southern Ocean nutrient depletion on atmospheric CO2 and ocean chemistry, Limnol. Oceanogr., in press.
Sarmiento, J. L., and E. Sundquist, 1991. Oceanic uptake of anthropogenic CO2: a new budget, Nature, submitted.
Sarmiento, J. L., J. C. Orr, and U. Siegenthaler, 1992. A perturbation simulation of CO2 uptake in an ocean general circulation model, J. Geophys. Res., 97, in press.
Siegenthaler, U., 1983. Uptake of excess CO2 by an outcrop-diffusion model of the ocean, J. Geophys. Res., 88, 3599–3608.
Stegen, G. R., K. H. Cole, and R. Bacastow, 1991. in Proc. IEA international conference on technology responses to global environmental challenges, Kyoto, Japan.
Tans, P. P., I. Y. Fung, and T. Takahashi, 1990. Observational constraints on the global atmospheric CO2 budget, Science, 247, 1431–1438.
Toggweiler, J. R., K. Dixon, and K. Bryan. 1989a. Simulations of radiocarbon in a course-resolution world ocean model. L Steady state pre-bomb distributions, J. Geophys. Res., 94, 8217–8242.
Toggweiler, J. R., K. Dixon, and K. Bryan. 1989b. Simulations of radiocarbon in a course-resolution world ocean model. 2. Distributions of bomb-produced 14C, J. Geophys. Res., 94, 8243–8264.
About this article
Cite this article
Orr, J.C., Sarmiento, J.L. Potential of marine macroalgae as a sink for CO2: Constraints from a 3-D general circulation model of the global ocean. Water Air Soil Pollut 64, 405–421 (1992). https://doi.org/10.1007/BF00477113