Ocean Urea Fertilization: A High Risk Plan and A Unified International Response
The Plan: The idea of stimulating the oceanic biological pump via increased primary production with the aim of ultimately increasing carbon sequestration as a means to offset climate change is not new. What is relatively new in the “prime the pump” schemes is the plan to use urea for this fertilization. Most carbon sequestration plans heretofore have suggested iron enrichment (e.g., Martin 1990), or direct injection of CO2 at depth.
|There is much that we still do not understand about how the oceans respond to large-scale enrichments, whether from urea, iron, or other compounds, and the scientific community can contribute in several ways… The current collective insight of the scientific community is sufficient to suggest that the environmental impacts may be large in some locales.|
Commercial enterprises are suggesting new approaches and new sites where nitrogen enrichment would presumably be effective.
The Ocean Nourishment Corporation of Sydney, Australia, has recently proposed several candidate sites for urea enrichment. One such site is the Sulu Sea, off the Philippines, and another is the Arabian Gulf. This report briefly summarizes how the international scientific community has responded, and why such a plan is of real concern environmentally. The plan for the Sulu Sea has been halted, at least at this point in time. Whether this plan proceeds in the Arabian Gulf or elsewhere is not yet resolved.
International Response: The international community has responded to the plans for ocean fertilization in a number of ways. Several position statements, which underscore the need for caution in ocean fertilization, have been issued by scientific groups, such as the Scientific Committee on Ocean Research (SCOR) and the Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP), an independent international advisory body of the United Nations (Urban and Haag 2008), as well as international projects, such as the Surface Ocean Lower Atmosphere Study (SOLAS) and the Global Ecology and Oceanography of Harmful Algal Blooms (GEOHAB). The London Convention, under the auspices of the International Maritime Organization, the body that oversees the dumping of wastes at sea, is examining the scientific and regulatory aspects of large-scale open-ocean fertilization experiments through a scientific working group. Last November, the parties of the Convention stated that such fertilization schemes were, “…not scientifically justified and they urged governments to exercise utmost caution when considering such proposals” (www.etcgroup.org, 9 Nov 2007); the Convention reaffirmed their concern in a report on ocean fertilization issued during their May 2008 meeting in Ecuador.
The Convention on Biological Diversity, to which 191 countries have signed (the US has signed but not ratified, and therefore is not a party to this Convention), meeting in Germany in May 2008, took the view that given the uncertainities in the outcomes of ocean fertilization, such efforts should not take place until there was a better assessment of the potential risks, and should not be used for the selling of carbon offsets (www.etcgroup.org, 30 May 2008). In effect, they proposed a moratorium on ocean fertilization.
There is much that we still do not understand about how the oceans respond to large-scale enrichments, whether from urea, iron, or other compounds, and the scientific community can contribute in several ways. Through carefully controlled, small-scale in situ, mesocosm, and laboratory experiments, and peer-reviewed reporting, new understanding can be gained about the biological and biogechemical response to fertilization (e.g., de Baar et al. 2005, Boyd et al. 2007, Buessler et al. 2008). The current collective insight of the scientific community is sufficient to suggest that the environmental impacts may be large in some locales. In the specific case of the plan to fertilize the Sulu Sea with urea, a group of 57 scientists from the US, South Pacific rim (Philippines, Malaysia, Australia, Vietnam, Indonesia), East Asia (China, Japan, Korea), Europe (France, Germany, Sweden, Denmark), Ireland, the Mid East (Oman, Kuwait), and South Africa, combined their expertise on urea metabolism, algal physiology, harmful algal blooms, eutrophication, hypoxia , local and regional oceanography, and carbon cap- and- trade economics, to outline the concerns over this plan, which were subsequently published in Marine Pollution Bulletin (Glibert et al. 2008).
Other organizations, such as the World Wildlife Fund for Nature, also raised their concerns. These concerns were heard, and the Philippine government declined permission for the Ocean Nourishment Corporation to proceed with their plan (although preliminary trials were apparently conducted). Without the strong voice of scientists, politicians and governmental organizations have little objective input on which to base decisions with respect to ocean fertilization; they have only the promises of the corporations that hope to profit from the endeavor. Such promises, which have included improved coastal fisheries and reductions on global warming, are enticing indeed.
Carbon Sequestration Plans and Urea: Urea enrichment shares many of the concerns that have been expressed for other carbon sequestration plans, such as iron fertilization (e.g., Chisholm and Morel , 1991, Buessler et al., 2008). The effectiveness of carbon sequestration is difficult to predict, interactions with other biological and biogeochemical processes are not well understood, and verification of the fate of fixed carbon particualry with respect to sequestration is very difficult. Methodology such as satellite imagery is not sufficient; such a method may only verify that a near-surface bloom has occurred, not its composition or its fate, including its extent of sinking.
Urea enrichment is of particular concern for several reasons. Worldwide use of urea as a nitrogen fertilizer and feed additive has increased more than 100-fold in the past 4 decades, including a doubling in just the past decade (Glibert et al. 2006), and there is considerable information about its commercial production, transport and fate. In many regions of the world where urea dominates the agricultural use of nitrogen fertilizer, increasing frequency and duration of toxin-producing dinoflagellates have occurred (Glibert et al. 2006). In the Sulu Sea, where urea fertilization was proposed, known toxic dinoflagellates include Pyrodinium bahamense and Gymnodinium catenatum, both of which cause paralytic shellfish poisoning, as well as Cochlodinium sp. which causes fish kills (Bajarias et al. 2006, Azanza et al. 2008). Harmful algae are also increasing in the Arabian Gulf, another site under consideration for urea fertilization. Moreover, there is some evidence that the toxin content of some harmful algae increases under urea enrichment (e.g., Shimizu et al. 1993, Leong et al. 2004). Many dinoflagellates also produce resting cycts during their life cycle, leading to the potential for new blooms even after the initial urea enrichment has ended.
If nutrients are added to a nutrient impoverished region of the ocean, new biomass will be produced. Although we know much about primary production, the relative rates of use and preferences for different nitrogen forms, and the biogeochemical pathways of nutrient cycling, there is much that is unknown about the fate of such added nitrogen. Whether fish are produced, whether carbon is sequestered to the deep sea, or whether much of the newly produced carbon is respired by way of an enhanced microbial loop, or denitrified leading to other greenhouse gases such as N20, will depend on where and when the enrichment is made, how much nitrogen (or iron) is added, whether the enrichment is pulsed or sustained, and the existing species composition. Promises of enhanced fish production, or the selling of carbon credits based on expected long-term sequestration, are premature at best. The positions of the London Convention and the Convention on Biological Diversity are to be applauded.
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