[World Ocean Nitrate Distribution via NOAA’s handy dandy Ferret]
For the first time, a group of scientists (oceanographers) have written a letter to one of the top tier science research journals, Science, warning against the use of ocean iron fertilization as a viable method to sell carbon credits. The group includes a number of highly accoladed researchers in the field, many of whom have themselves organized such enrichment experiments for research purposes (including UBC alumnus, Phil Boyd). According to the authors (subscription required):
The consequences of global climate change are profound, and the scientific community has an obligation to assess the ramifications of policy options for reducing greenhouse gas emissions and enhancing CO2 sinks in reservoirs other than the atmosphere[…]
[…]The efficacy by which OIF sequesters atmospheric CO2 to the deep sea remains poorly constrained, and we do not understand the intended and unintended biogeochemical and ecological impacts. Environmental perturbations from [ocean enrichment experiments] OIF are nonlocal and are spread over a large area by ocean circulation, which makes long-term verification and assessment very difficult. Modeling studies have addressed sequestration more directly and have suggested that OIF […] would be unlikely to sequester more than several hundred million tons of carbon per year. Thus, OIF could make only a partial contribution to mitigation of global CO2 increases.
Despite these uncertainties in the science, private organizations are making plans to conduct larger-scale iron releases to generate carbon offsets. We are convinced that, as yet, there is no scientific basis for issuing such carbon credits for OIF.
What is Geoengineering Anyway?
According to Wiki, geoengineering is the, “deliberate modification of Earth’s environment on a large scale “to suit human needs and promote habitability”” In a climate change context, it involves purposely altering the Earth’s surface to help mitigate climate change. There have been a number of proposed geoengineering projects over the last few decades (yea…decades, this isn’t new), but only within the last 10 years have OIFs come into popularity among business types.
Why Iron Enrichment?
In the 1980’s, scientists were trying to determine why there were large expanses of the global ocean that had excess plant nutrients (think about nitrates and phosphates in fertilizers; see above image). This indicated that a particular variable was preventing the single celled plant-like cells (phytoplankton) that grew there from using it all up as in other areas of the world. After a dozen or so large-scale experiments in these regions, and nearly 15 years of research later, oceanographers are confident that these areas of the ocean lack a very important nutrient: iron.
Iron is required by nearly all living things. It’s a member of the transition element family on the periodic table, and, like many of its brethren, has the capacity to pass electrons between different molecules. This atribute is invaluable when it comes to organismal metabolism, since electron transfer reactions lie at the heart of how our cells produce energy everyday. In fact, some estimates put greater than 90% of the total iron of a phytoplankton cell inside the chloroplast, the intracellular subcompartment whose molecular machinery turns carbon dioxide, with the help of light, into sugars.
So, when you don’t have enough iron (like a human anemic), you don’t do very well, do you? In the case of phytoplankton, they aren’t able to produce the sugars they require to grow, as well as a number of other very important metabolic processes iron is involved in.
Why Is Iron Limiting?
This is a complex question to answer, but the short version is: there isn’t enough iron reaching the afflicted areas, and what is present in the water is in a chemical form that is more difficult to use than areas where there is a larger input of iron. The result: growth limitation.
Why Carbon Credits?
As I said above, phytoplankton turn carbon dioxide into sugars. This process, often referred to as “carbon fixation” (i.e. “fixing” carbon from a gaseous state into non-gaseous state), draws CO2 out of the water. Now, if phytoplankton cells happen to sink below the surface layer of the ocean that is in constant contact with the atmosphere (via wind mixing), then the CO2 that was fixed is now effectively removed from the atmosphere, or “sequestered”. The removal of CO2 as a gas in the surface to the deep waters as a non-gas results in the transfer, or “biological pumping” as its often referred, of carbon away from the atmosphere. Thusly, the idea is, if you add iron to iron-limited areas of the ocean, and you can pump more CO2 out of the atmosphere and into the deep water where it is likely stored for a few hundred years.
What’s The Problem?
Carbon-credit companies propose to use this sequestering phenomenon as a way to sell carbon credits to polluting companies that want to offset their carbon imprint on the planet. The problem is, we don’t know nearly enough about the phenomenon and the implications of larger scale (both spatially and temporally) “dumpings” of iron into the ocean.
There are a number of potentially disastrous impacts OIFs could have, many of which, without going into detail, are real and not the result of wild speculation (i.e. large-scale anoxic bottom water events that could kill all the fauna present, the biological production of other, nastier greenhouse gases as a byproduct of the enrichment, no significant effect at all on carbon sequestration from the atmosphere). In fact, OIFs could do much more harm than good on a global scale, especially if left to companies whose bottom line might supersede science.
I encourage anyone who is interested in more of the science to read the the letter linked to above (if you’re on the UBC or any other university network, you should have access to it). Also, here’s a fairly recent and very thorough series of articles in Oceanus, WHOI‘s oceanography publication (link.)