On the basis of available scientific information, we cannot dismiss ocean fertilization with iron as a mitigation option. However, computer models predict that it would at the very best reduce the expected increase of atmospheric CO₂ by a small percentage¹. Achieving this degree of sequestration would entail major alterations of the ecosystem ¾ such as changes in food web structure and biogeochemical cycles ¾ as has been demonstrated in several research experiments to date. These changes will have unknown consequences, some of which will be inherently unpredictable.

There is commercial interest in small-scale fertilization experiments to better understand the ocean carbon cycle and to take advantage of anticipated carbon credits. Given the present state of knowledge and technology, it is premature to justify carbon credits for ocean fertilization.

For example:

• There is no current capability to verify the amount and time scales of CO₂ sequestration resulting from ocean fertilization.
• It is difficult to assess biogeochemical and ecological consequences of fertilization in patches.² Far-field, long-term and cumulative effects of nutrient applications must be described. This will require computer models validated through observations and process studies.
• Fertilization will very likely result in increased marine emissions of atmospherically important substances, with unknown consequences. These emissions include the potent greenhouse gases nitrous oxide and methane, as well as dimethyl sulfide (which influences cloud formation) and halogenated compounds that are important for the oxidation (cleansing) capacity of the atmosphere.

More fundamentally, there are profound deficiencies in our understanding of a broad range of ocean-atmosphere processes that must be addressed in order to assess the role of the oceans in climate regulation both through natural (via atmospheric mineral matter) and intentional iron enrichment.

Recognizing that the global ocean common requires special governance, and that both private and public resources will be used for carrying out the necessary scientific and policy research, partnerships should be created among academic scientists, industry, and government.

Examples for partnerships may come from the biomedical field, as well as other agreements governing the use of the sea.

No appropriate intergovernmental governance structure has been identified with specific authority for ocean fertilization, although many elements of existing treaties and conventions may be applicable to some portion of the ocean fertilization issue. International agreements on activities in the high seas have, for example, advanced the principles of a precautionary approach, the liability of polluters ("polluter pays"), transgenerational equity, and sharing knowledge and benefits.