Ocean Fertilization Geoengineering: Time to Stop?

The drumbeats for geoengineering responses to climate change are getting louder, evinced recently by the first U.S. Congressional hearings on the subject in November, with more to follow this year. An interesting reading on one of the most prominent so called “long-wave engineering” methods, ocean iron fertilization, is Aaron Strong, et al., Ocean Fertilization: Time to Move On, 461 Nature 347-48 (Sept. 2009).

Among the takeaways from the article are the following

  1. If iron fertilization is successful, nutrients such as phosphorus and nitrogen would sink along with carbon, “altering biogeochemical and ecological relationships throughout the system.” This could result in anoxia in large swaths of the ocean, with potentially dramatic impacts on marine organisms from microbes to fish;
  2. Unlike some other geoengineering techniques that might be effectively tested on a small scale, ocean fertilization would require field testing that encompassed large swaths of ocean, and an assessment would require decades to a century. Moreover, the assessment might be bedeviled by the ongoing impacts of climate change. The authors advocate allowing small-scale experiments, of which there have been 11 since 1993, to continue, but to ban larger projects aimed at exploring fertilization’s  geoengineering potential because we cannot resolve critical issues about ocean fertilization as a mitgiation strategy;
  3. Ocean fertilization is by no means a magic bullet. Even if the entire Southern Ocean were fertilized forever with iron to overcome macronutient  limitations, less than 1 gigaton of carbon annually could be sequestered, compared to probable future emissions of 8 gigatons annually;
  4. While companies conducting fertilization experiments currently, e.g. the San Francisco-based CLIMOS, might contemplate selling carbon offsets from such activities, the Kyoto Protocol’s Clean Development Mechanism doesn’t recognize credits from geoengineering, so such credits would presumably have to be sold on the voluntary carbon market;
  5. The London Convention has developed an assessment framework for ocean fertilization, which seeks to limit such experiments to those that constitute “legitimate scientific research,” though it hasn’t yet made a determination as to whether experiments that seek to lay the framework for generation of carbon credits would fall under this rubric.

Beyond the themes developed in the article, some relevant discussion questions for students might include the following:

1. Given the potentially profound impacts that climate change under a business as usual scenario will visit upon the oceans, might a comparative assessment of the impacts of ocean fertilization determine that it is ultimately cost beneficial despite the potential negative ramifications? If this were the case, should we allow research in this context to continue, including large-scale field trials?;

2. If it were to be determined that ocean fertilization would, on balance, be beneficial on a global scale, should we ban such operations if it produces negative regional results?;

3. What legal regimes beyond the London Convention might be relevant to ocean fertilization geoengineering?

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