Ocean fertilization is a controversial method proposed for mitigating rising atmospheric CO2 levels and associated climate change by stimulating net phytoplankton through the release of nutrients, such as iron, into certain parts of the surface ocean. The oceans are currently responsible for removing a significant quantity of the CO2 added to the atmosphere by human activity each year, and this carbon may be sequestered in the ocean for hundreds of years.
Iron can be a limiting nutrient for phytoplankton growth, especially in certain high-nitrogen, low-chlorophyll areas found in parts of the Southern Ocean, the equatorial Pacific Ocean and the sub-Arctic Pacific Ocean. Ocean fertilization involves the addition of iron sulfate or other nutrients to surface waters in these areas from a ship or a pipeline, or the pumping of nutrient-rich waters from the deep ocean into sunlit waters. Research experiments fertilizing the ocean in this way resulted in phytoplankton blooms. The theory is that phytoplankton then take up carbon from sea-water, a portion of them sink to the deep sea and sequester carbon removed from the atmosphere. Increasing the sequestration of carbon in the ocean could assist in decreasing the CO2 concentration in the atmosphere until our global energy economy can make the transition to fewer CO2 emissions. Because so much carbon might be sequestered, ocean fertilization is an exciting prospect for the carbon trading market, but it requires a solid scientific basis to move forward. So far, information about sequestration potential and environmental impact is limited.
While several important studies of ocean fertilization have been undertaken, the efficacy by which it sequesters atmospheric CO2 to the deep sea remains poorly understood, and we do not understand the full range of biogeochemical and ecological impacts. Potential impacts include increased emissions of biogenic gases to the atmosphere, decreased oxygen content of the underlying waters, and alteration in the living marine community - from microbes to megafauna.
What IUCN is doing
The commercial sector is becoming interested in funding research to answer questions about ocean fertilization with a view to exploring its potential as an effective avenue for mitigating climate change. One way to fund such research is by selling carbon offsets. To do so, it will be necessary to demonstrate that ocean fertilization effectively and quantifiably removes CO2 from the atmosphere, retains that carbon in the deep ocean for at least 100 years and that the environmental impacts are predictable and acceptable.
Ocean fertilization projects must demonstrate that they do not pollute the marine environment, which would be contrary to the requirements of the UN Law of the Sea Convention. In the context of marine geo-engineering projects, Art. 195 of the UN Law of the Sea Convention requires countries not to transfer damage or hazards (e.g., excessive atmospheric greenhouse gases) from one area (the atmosphere) to another (the ocean) or transform one type of pollution (e.g., potentially harmful concentrations of greenhouse gases in the atmosphere) into another (e.g., potentially harmful concentrations of greenhouse gases in the ocean). Under the Convention marine geo-engineering projects, including those that involve ocean fertilization, might under certain circumstances constitute pollution of the marine environment, and if geo-engineering experiments cannot meet the legal requirements for the protection of the marine environment they should not be allowed to go forward.
Ocean fertilization also falls under the London Convention and London Protocol on Prevention of Marine Pollution by Dumping of Wastes and Other Matter. The 30th Meeting of Parties to the London Convention and Protocol in October 2008 proposed a politically binding resolution which, given the present state of knowledge, effectively prohibits all ocean fertilization activities other than ‘legitimate scientific research’ projects. Scientific research proposals should be assessed on a case-by-case basis and Contracting Parties are urged to use utmost caution to ensure protection of the marine environment.
What is at stake ?
Concerns have been raised about the potential environmental impacts of such research. The effects of large-scale marine geo-engineering involving ocean fertilization are presently unknown and may not be reversible. Given the uncertainties it is difficult to judge the relative magnitude of risks involved. Even individual ocean fertilization experiments could result in significant adverse impacts to the marine environment if conducted inappropriately or in proximity to particularly sensitive sea areas.
Another challenge lies in monitoring impacts of ocean fertilization experiments. Fertilized ‘patches’ move in three dimensions and currently monitoring does not provide information on the whole volume fertilized. Unintended impacts may occur beyond the fertilized patch and the area being monitored. Quantifying the amount of carbon sequestered is also difficult and carbon credits should not be issued if carbon sequestration cannot be persuasively quantified. There is also concern that research projects might be used for generating and selling carbon offsets, and that commercial interests in the scientific research might possibly bias the reported outcomes. To get fertilization credits on the voluntary carbon market, the public should have confidence that the technology is safe, effective and verifiable. Public perception is key. It is important to ensure that any research done to study ocean fertilization is of high quality, that the data are open and reviewed scientifically, and that environmental impact assessments are conducted. Distinctions must also be made between marine geo-engineering experiments and experiments involving fertilization designed to improve our knowledge of phytoplankton ecology and dynamics.
What is IUCN doing
IUCN organized a workshop on ocean fertilization at the World Conservation Congress in Barcelona in October 2008 bringing together key players in the field. The views expressed herein do not necessarily reflect those of any of the participants in the Barcelona workshop. IUCN plays an important role in discussions about ocean fertilization in the London Convention and other international fora such as the UN General Assembly, the UNICPOLOS (United Nations Informal Consultative Process on Oceans and Law of the Sea), the UNFCCC (United Nations Framework Convention on Climate Change) and the Convention on Biological Diversity (CBD). IUCN represents the environmental and ecological perspectives on this debate and urges extreme caution on proceeding with large-scale ocean fertilization activities before further environmentally-responsible studies are undertaken and improved understanding exists. IUCN considers that the sale of carbon offsets for such research is premature.