Part IV of “What . . . About Geoengineering” discussed a plan for reducing concentrations of carbon dioxide in the atmosphere by fertilizing the ocean with iron. According to the plan, the iron would promote the growth of algae, which would diminish the ranks of carbon-dioxide molecules by absorbing the carbon. Ultimately, the heroic little algae would die and carry the absorbed carbon to its final resting place on the ocean floor, where it would remain (with any luck) for eternity.
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And now, with that brief recap of Part IV, we’re back up to speed, so let’s talk about some reasons why ocean iron fertilization (OIF) might not be such a great idea.
Let’s start with what happened when the “Lohafex project” fertilized a 116-square-mile (300-square-kilometer) patch of the Southern Ocean with six metric tons of iron. Initially, the fertilization appeared to be a success. Just as in previous experiments, a floating green carpet of algae quickly covered the undulating waters. Before two weeks had passed, however, the algae (not being the brightest of creatures) had forgotten that the scientists had only created this hospitable environment for the sake of carbon-dioxide absorption. And the little green dickens, instead of focusing on the job at hand, had taken it upon themselves to act out their autotrophic, bottom-of-the-food-chain role! As you might imagine, the scientists were more than a little dismayed when they discovered that a herd of copepods (tiny crustaceans) were gobbling up their algae. Due to the copepods’ gobbling, few of the algae lived long enough to die from natural causes and drop to the ocean floor. Professor Victor Smetacek explained the significance of the experiment’s outcome, saying: “What it means is the Southern Ocean cannot sequester the amount of carbon dioxide that one had hoped.” Alas and alack.
So one problem with ocean iron fertilization is that it depends on algae remembering that they’ve only been bred to absorb CO2: Any extra-curricular oceanic activities are strictly verboten. To put it another way, OIF is ineffective if various sea critters gulp up the algae before the algae have had a chance to gulp up the carbon and deposit it on the ocean floor. That’s Problem #1. Problem #2 is the actual—as opposed to theoretical—cost. The actual cost would depend on the effectiveness of each voyage. If the first voyage failed to produce significant results, then another or perhaps several subsequent voyages would be required, raising the cost substantially. Said seagoing scientist Ken Buesseler: “You would have to keep doing it over, and if you wanted to have a big impact the size of the area required is bigger than the Southern Ocean.” OIF is unlikely to be cheap, in other words.
A third potential problem: Successful algal blooms could deplete the water of vital nutrients, such as nitrate, phosphate, and silica. Which brings us to Problem #4. If the fertilization were to work as planned, and each little alga, plumped up with carbon, found its way to the bottom of the sea, the decomposition of the sunken algae’s organic matter could deprive the deep ocean—and the life therein—of oxygen; or, Problem #5, the decomposition could release methane and nitrous oxide, both of which are more potent greenhouse gases than CO2. (Phew!)
But that’s not all. Problem #6: Studies have shown that enriching ocean waters with iron stimulates the growth of a diatom, Pseudonitzschia, which produces a neurotoxin, domoic acid. That’s bad news for us because we can sustain permanent brain damage (from amnesic shellfish poisoning) if we eat seafood contaminated by the neurotoxin. Problem #7: Dumping iron in any sizeable amount violates an international treaty, the UN Convention on Biological Diversity, so parties to the treaty would have to agree to amend it for full-scale OIT to take place. Problem #8: If we make this our strategy for counteracting the impact of ongoing CO2 emissions, we’re going to have to commit ourselves to managing the oceans indefinitely. Field tests have already shown us some side effects of OIF, but who the heck knows what all the unintended consequences—biological, ecological, and geopolitical—would be?
So maybe ocean iron fertilization does have a few flaws. But, prithee, me hearty, and shiver me timbers; do not discouraged be, for geoengineers have come up with another ocean-centered, carbon-dioxide-removal proposal. They call this one: “liming the ocean.” (Blimey, limey!) Liming is a bit like OIF. You sail out to sea, but when you reach your destination, instead of adding iron, “you put the lime in the coconut,” I mean, you stir a bit of lime (derived from limestone) into the water, and the lime, which is alkaline, makes the saltwater less acidic, and that enables the water to absorb more carbon dioxide. Problems? Yes. Some known; others yet to be discovered. One of the known problems is that the lime-producing process is energy intensive. It requires heating limestone carbonate rocks to “drive off” the carbon dioxide and then finding somewhere to sequester the driven-off CO2.
And that’s a bit of a problem because, in the words of Robert Bryce of the Manhattan Institute, “carbon dioxide is a worthless waste product.” We might get rid of a bit of it by injecting it into oilfields or selling some of it for use in chemicals and soda pop as China does, but, currently, there really isn’t much of a market for the stuff. So if we decide to get into the carbon-capture-and-sequestration business, taxpayers will likely be on the hook for transporting and storing the CO2, and we would have to commit to keeping it safely in storage for a very long time, if not forever.
So now that you’ve read the above, which of the following makes more sense to you: (a) deploying one of these (#?%&*!!) plans to geoengineer the ocean or (b) acting as individuals to lessen our greenhouse-gas emissions by reducing our consumption of resources and production of wastes?
While you’re pondering that question, I’ll be busy preparing Part VI. So please join me for the next installment of “What You Always Wanted to Know About Geoengineering but Were Afraid to Ask,” which will (most likely) discuss the thrilling topic of carbon sequestration. In the meantime, rest up and prepare yourself for our next rip-roaring adventure!
 Dawicki, Shelley. “News Release: Effects of Ocean Fertilization with Iron to Remove Carbon Dioxide from the Atmosphere Reported.” Woods Hole Oceanographic Institution. April 16, 2004. http://www.whoi.edu/page.do?cid=886&ct=162&pid=9779&tid=282 (Accessed December 4, 2013.)
 Powell, Hugh. “Fertilizing the Ocean with Iron.” Oceanus. Woods Hole Oceanographic Institution. November 13, 2007. http://www.whoi.edu/oceanus/viewArticle.do?id=34167 (Accessed December 4, 2013.)
 Trick, Charles G., Brian D. Bill, William P. Cochlan, Mark L. Wells, Vera L. Trainer, and Lisa D. Pickell. “Iron Enrichment Stimulates Toxic Diatom Production in High-Nitrate, Low-Chlorophyll Areas.” Proceedings of the National Academy of Sciences. Vol. 107, no. 13, pp. 5887-5892. http://www.pnas.org/content/107/13/5887.full.pdf+html (Accessed November 30, 2013.)
 Fehling, Johanna, David H. Green, Keith Davidson, Christopher J. Bolch, and Stephen S. Bates. 2004. “Domoic Acid Production by Pseudo-Nitzschia Seriata (Bacillariophyceae) in Scottish Waters.” Journal of Phycology. Vol. 40, no. 4, pp. 622-630.
 Webersik, Christian. 2010. Climate Change and Security: A Gathering Storm of Global Challenges. Santa Barbara, CA: Praeger; Black, Richard. “Setback for Climate Technical Fix.” BBC News. March 23, 2009. http://news.bbc.co.uk/2/hi/7959570.stm (Accessed November 30, 2013.)
 Society of Chemical Industry. “Adding Lime to Seawater May Cut Carbon Dioxide Levels Back to Pre-Industrial Levels.” Science Daily. July 21, 2008. http://www.sciencedaily.com/releases/2008/07/080721001742.htm (Accessed November 30, 2013.)
 The Royal Society. 2009. Geoengineering the Climate: Science, Governance and Uncertainty. RS Policy Document 10/09. London: Royal Society, p. 14.
 Bryce, Robert. “A Bad Bet on Carbon.” New York Times. May 12, 2010.