Is Ocean Fertilization a Good Carbon Sequestration Option?

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Massachusetts Institute of Technology

2002

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EXECUTIVE SUMMARY

The Policy Issue

The proliferation of fossil fuel-based technologies in the face of a discernible impact of

anthropogenic “greenhouse gas” (GHG) emissions on global climate presents an urgent challenge to

develop other mechanisms for mitigation of the “greenhouse effect”. Much attention has focussed

upon ways to curtail the growing stock of atmospheric carbon dioxide (CO2), a major greenhouse

gas, by enhancing the natural “sinks” or processes that remove CO2 from the atmosphere. Among

the various approaches proposed, a set of controversial – and increasingly prominent – ideas

involve efforts to “short circuit” or “enhance” the natural transfer of atmospheric carbon dioxide into

the deep ocean. One such approach involves the addition of otherwise scarce (“limiting”) nutrients

to surface ocean waters to manipulate marine biological production, thus potentially changing the

flux of carbon dioxide between the atmosphere and ocean.

It has been hypothesized that releasing limiting nutrients into the euphotic (i.e., sunlit) surface layer

of the ocean on a large-scale could stimulate the growth of marine phytoplankton, thus increasing

the biologically-mediated uptake of atmospheric CO2 by the ocean and mitigating the greenhouse

effect. Results from four open ocean experiments have shown that dissolved iron limits primary

production in certain nutrient rich regions of the ocean. Results of these scientific experiments,

which were designed without specific applications in mind, have catalyzed a variety of commercial

interests in manipulating the biological carbon pump by varying the availability of nutrients. While

continuing scientific research effort addresses the many ecological uncertainties associated with

nutrient manipulation in the marine environment, entrepreneurs have been busy marketing different

methods for large-scale ocean fertilization (hereafter simply “fertilization”) to remove carbon dioxide

from the atmosphere. Seven US patents for fertilization methods have been issued during the past

seven years and an application for an eighth was filed in January 2001. Meanwhile, corporations

and governments have shown a growing interest in “early action” in order to hedge their bets with

respect to the adoption of some kind of GHG trading system in the future. Patented fertilization

methods are actively being marketed to such corporations and governments, and coastal nations

have also been propositioned to serve as “hosts” for the generation of potentially valuable carbon

credits by ocean fertilization in the prospective hosts’ territorial waters. Despite these remarkable

developments, the necessary dialogue on scientific evaluation criteria for large-scale ocean

fertilization is seriously lacking. As a result, most corporations, governments and other stakeholders

are ill equipped to properly assess the risks, benefits and true costs associated with proposals for

fertilization.