Ocean Iron Fertilization - the next big . . . ?

Recently at the Intersection, Chris Money reported on current efforts to get permission for iron fertilization of the ocean. He was using this specific example to spark a larger debate about the efficacy of geoengineering – essentially human manipulation of Earth systems to meet human needs and “right” human wrongs. As a science fiction fan, I'm very familiar with geoengineering's close cousin terra forming. I understand the processes very well, and I'm actually intrigued by any such activity.

Now, a disclaimer – I work for one of the federal agencies that are considering whether to permit this scheme. I don’t work in the office handling it, nor have I seen the application. I have read a lot of scientific, peer reviewed literature on ocean iron fertilization, and I have encountered a number of views on the subject. So what I’m about to write is NOT the official position of any government agency I am or have worked for. It’s my own synthesis. Period.

The idea behind ocean iron fertilization is that iron is a limiting nutrient for phytoplankton in the ocean. That means the microscopic plants that live in the first few inches of the ocean can’t grow because there isn’t enough iron for them to grow from. Iron, along with nitrogen and phosphorous, is a key fertilizer for all plants, and an iron deficiency can in fact limit plant growth. So the idea is to add a lot of elemental iron to several open ocean spots to cause huge phytoplankton blooms. The proponents of this idea say the big blooms will soak up atmospheric carbon dioxide, thus lowering levels of a significant green house/ climate change inducing gas.

As a scientist, I have to ask – what is the science behind this? Are there peer reviewed studies that argue for or against the idea? And are there existing examples of similar activities that might guide an analysis of this idea?

There is lots of literature on Ocean Iron Fertilization. What seems to be missing from these analyses, however, is reference to unintentional but persistent existing ocean features that might mimic this process, and can offer what I think are significant insights.

Every year, the Northern Gulf of Mexico goes, biologically, dead. This death is due to a significant load of nutrients – including phosphorous, nitrogen and iron – washing down the Mississippi River each spring. Since the Mighty Muddy drain about 2/3rds of the nation, it’s no wonder it would have a huge nutrient load when it exits the continental US at Venice, Louisiana. The Gulf Dead zone was first documented in 1972, and the Louisiana Universities Marine Consortium (LUMCON) has lead research on it every since.

The Gulf Dead Zone reaches between 6,000 and 7,000 square miles per year. It results when all the nutrients power a huge phytoplankton bloom. Once the plankton run of food, they begin to die, sinking to the bottom. On the way down, and on the bottom, they cause serious oxygen depletion as they decompose. This hypoxic zone has periodic fish kills, and all sorts of marine animals are known to run from it, literally for their lives. And sadly, while the Northern Gulf Dead Zone is the largest, it’s not the only one.

So what does this mean for ocean iron fertilization? I think it means we need to proceed with extreme caution. If run-off fed blooms can pull oxygen out of the water on the continental shelf and continental slope, what will an iron created bloom do to open ocean ecology? Will the cost to marine life through out the water column be worth the pay off in carbon dioxide reduction? And should we really alter natural phytoplankton systems because our modern economy won’t (yet) adjust to a more carbon limited model?

My own gut tells me we’ve done enough damage to the Earth already. I don’t think there needs to be a large scale ocean iron fertilization action. But I’m still open to the science, and if there are good, peer-reviewed papers that show how this might actually work, and what the water column impacts would be – I would be open to where that science led me.