Iron Fertilization: Savior to Climate Change or Ocean Dumping?

Massive coccolithophore bloom in the Barents Sea. These blooms are caused by high levels of sunlight in the arctic summer, and the right combination of nutrients to allow growth. By Jeff Schmaltz (NASA Earth Observatory).

Unbeknownst to most scientists until a few days ago, two hundred thousand pounds of iron sulphate were dumped into North Pacific Ocean in July, with the aim to trigger a large plankton bloom. This experiment was conducted by the Haida Salmon Restoration Corporation, under the direction of businessman Russ George. Why dump this dirty brown powder into the ocean and why to trigger a plankton bloom? All in the name of reversing man-made climate change.

Phytoplankton is photosynthetic, needing sunlight and nutrients to grow, taking up carbon dioxide in the process and producing oxygen as a by-product. This phytoplankton then dies, falling to the bottom of the ocean, and taking that ‘sequestered’ carbon dioxide with it, trapping it at the bottom of the ocean. One of the major nutrients phytoplankton needs to grow is iron, an insoluble nutrient and often found in limited quantities, inhibiting large plankton blooms from occurring. So by adding iron to the ocean, we can increase the numbers of phytoplankton photosynthesizing, using up more carbon dioxide from the atmosphere and locking it up, deep in our oceans.

Or at least that’s the theory. Geoengineering is the term coined for deliberately modifying our environment to tackle man-made climatic changes on a global scale. It all sounds so simple – an easy route to solving our carbon emission crisis. The controversy comes that we don’t fully understand the consequences of manipulating our environment on a global scale, and we have to weigh up whether those consequences are better, or worse, than the problem we are trying to fix. We’ve seen what’s happened time after time when we’ve modified the food chain – fisheries collapses, extinction of species – we know well that connections that seem small can have drastic consequences we didn’t even consider. In addition, as that large bloom dies, decay will use up oxygen, potentially creating large anoxic zones, smothering important bottom habitats in the deep ocean.

The ‘experiment’ that was executed by George and colleagues is primarily under fire because it was done undercover, without scientific peer review or process, and without international collaboration, yet can have global consequences. It is also the largest iron fertilization experiment to have occurred anywhere – 200,000 pounds versus a few thousand pounds. Other smaller scale international experiments over the last fifteen-plus years have concluded that the sequestering efficiency is low (and sometimes no effect was seen) – the amount of iron you’d need to make even a slight dent in our carbon emissions is in the million tons per year, and even if you put in that amount, it may just not work. Unregulated iron fertilization on this scale could have dramatic consequences and goes against an international moratoria created by the UN to protect ocean environments. Far from being a savior, this experiment is being called a large scale dumping of waste into our oceans.

What do you think, was it a worthwhile test or badly handled? 

Changing Planet

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Meet the Author
Dr. Rhian Waller is a professor of Marine Sciences at the Darling Marine Center (University of Maine, USA) and specializes in the ecology of deep-sea and cold-water organisms, particularly corals. Rhian has led or participated in over 40 international research and exploration cruises and expeditions to some of the most remote parts of the planet, and has published over 30 scientific papers and book chapters in her 9 year career. She is passionate about educating the next generation of scientists, and conserving our little known deep-sea and polar ecosystems to be studied and enjoyed in the future.