Sequestering carbon in the ocean is hard to do, and even harder to measure

A new paper by Wilmers et al. in Frontiers in Ecology and the Environment, which features a neat analysis of how carbon uptake in kelp forests is affected by the sea otter population, illustrates the likely folly of creating a carbon credit business through fertilizing the ocean with iron, the science and environment scandal of the month.

The proponent of the iron dumping off Haida Gwaii last month, Russ George, claims to be a hero who is trying to fight climate change. Most other observers see him as a businessman hoping to raise money selling carbon offsets or carbon credits.

It is hard to see how this could ever become a credible business. In order to sell carbon credits, you'd to:

a) need to prove fertilizing the ocean with iron does lead to long-term storage of carbon in the deep ocean, an open question discussed in my previous post,
b) be able to measure how much carbon was stored

Even if (a) is proven correct, the accounting problem (b) remains.

This is where the Willmers et al. paper comes in. Kelp forests, common on the west coast, are among the most productive marine ecosystems, sucking carbon out of the atmosphere at high rates. You haven't been diving until you've had to unravel yourself and your gear from metres long strings of kelp. Willmers et al. calculates that kelp forest store about ten times more carbon is sea otters are present, because without the otters eating the urchins, the urchins eat all the kelp. As such, there could be a carbon incentive, and potentially a market, to maintaining healthy otter and kelp populations (no easy feat).

The problem? Just as in the iron case, it's really hard to measure how much of the carbon taken up by the kelp gets exported to the deep ocean, where it would be sequestered long-term. Since there's no precise data, the authors provide estimates of carbon export over a range of 1% to 50% of the kelp carbon uptake. This no fault of the authors: deep carbon export from productivity on the surface is hard to measure and predict, so they've chosen an uncertainty range. The huge range is reasonable for the discussion section of a paper on carbon uptake in kelp forests. But it won't fly with accountants who need to sell the carbon credits.

(Photo credit: Monterey Bay Aquarium)

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Is the iron fertilization project off Haida Gwaii a science experiment, business opportunity, or uncontrolled geoengineering?

News outlets around the world are buzzing with evidence of a recent attempt to fertilize the ocean off the BC coast with iron pushed by a US businessman and funded in part by a group called the Haida Salmon Restoration Corporation.

The driving force behind the project, Russ George, is notorious in oceanography circles for the company Planktos, which tried and thus far has failed, to create a carbon credit business out of fertilizing the ocean with iron. The current project is like a bad movie script, complete with the a maverick businessman, international treaties, global environmental challenges, local environment costs, possible exploitation of innocent people, you name it.

From what I have learned so far, it looks like the only redeeming thing out of this event is it will give my biogeochemistry class something to discuss next week. I'll tackle my two science-based concerns, then discuss the two broader issues:

The science of fertilization 

Iron is limiting to algae growth in much of the open ocean, which means if you add iron to the ocean, algae will uptake more carbon from the atmosphere via photosynthesis. However, creating a plankton bloom does not necessarily permanently remove carbon from the atmosphere. For that, the organic carbon produced through photosynthesis needs to be sequestered in a some reservoir which, unlike algae or most plants, has a long-life time (otherwise, it could decompose and be returned to the atmosphere as carbon dioxide).

If you were trying to sequester carbon by fertilizing a grassland, the key would be getting that the organic carbon produced by the grasses into the deep soil, where it will stay for a reasonably long time. In the ocean, the organic carbon needs to be exported to the deep ocean, and stay there, ideally getting buried sediments. There it could conceivably remain for thousands of years, rather than returning to the atmosphere. So you need to track the sinking of carbon from the surface, through dead plankton, fecal pellets of things that eat plankton, etc. And, yes, I wrote fecal. If you want to do biogeochemistry, you do have to talk about feces, it is one of the most important mechanisms through which the planet recycles key nutrients.

The key question then is not "How big is plankton bloom?", but "How much carbon was exported into the deep ocean?". This has been the subject of a huge amount of research in the past 20 years. The scientists quoted in the news articles are extremely critical because they know iron fertilization is very complicated. This group does appear to be doing a suite of follow-up measurements, the details of which I do not. Without a huge investment in such measurements over very long periods of time - and I mean months to years, not days to weeks - it would be hard to take this project seriously.

The ancillary benefits 

One of project rationales appears to be that it might help the local ocean and ideally the salmon fishery. To use a popular word, this is a bunch of mularkey.  I'm not an expert on salmon, and I can't speak to the specific details of marine ecology off Haida Gwaii. The NW Pacific Ocean is not enclosed fish farm where adding some fertilizer means more algae for the fish to eat and thus more or bigger fish. In an open system with complex ecology, the long-term effect of the bloom on the fishery is highly uncertain.

The supposed salmon connection strikes me as a marketing cover story. It's no secret that the proprietor of Planktos who set up this organization with the Haida has been trying for years to create an business selling carbon credits or offsets through iron fertilization of the ocean. Even the current incarnation with the Haida has a clear carbon credit aim. The web-site lists a "sea" and "trees" side to the business. The trees side is directed towards forest restoration, clearly with the goals selling carbon credits for protecting or restoring the old growth in the region. Salmon is king here in B.C., slapping 'salmon restoration' onto a project gives it an air of nobility.

The media coverage has done a decent job representing these points about geo-engineering and marine ecology, thanks in part to the outrage among scientific experts who have been quoted. I'll close with a two non-scientific aspects of the coverage which I found a bit troubling:

The role of the Haida

Every story I've seen mentioned the possibility that Russ George is "taking advantage of the Haida". This claim may be well intentioned. Unfortunately, it is also rather paternalistic. It plays into some very old-fashioned racial assumptions, implying that the first nations people were bamboozled by some white man with money and fancy ideas. It may just be that the local people chose to be involved, not out of ignorance, but out of an understanding of the potential financial benefits of setting up a carbon offset business.

Is this geo-engineering?

Michael Tobis raises this important point. The existing geo-engineering treaty is non-binding, meaning the language in the treaty is aspirational and there are no penalties to ignoring the proposed ban on geo-engineering projects.

But we need to ask a broader question. If there were a legally-binding international ban on geo-engineering, would this stunt count? If every one-off dump of iron filings into the oceans counts as geo-engineering, shouldn't every tree planting project?

Definitions will really matter here. A binding treaty would need to set some minimum climate or carbon impact on projects, otherwise a lot of what people and companies do as a part of their everyday business will count at geoengineering. We need to, er, see the forest for the trees. A geo-engineering treaty should be there to control against dangerous large-scale experiments, like reducing the incoming solar radiation, not every carbon sequestration effort.


Given this last point, I think if we are to prosecute the organizers of this stunt off Haida Gwaii, it should be for the marine pollution, like an oil spill, rather than the attempt at geoengineering.

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Search trends show more interest in the Pacific garbage patch than other ocean threats

As I mentioned on Twitter yesterday, ocean acidification appears to be surpassing coral bleaching in the public imagination, at least according to a comparison of Google searches over the past few years.

Attention to ocean acidification and coral bleaching is now far surpassed by attention to the Pacific garbage patch.

Many factors may be at play here, including NGO and media focus on the Pacific garbage patch. Regardless, I can't help but wonder if the dominance of the garbage patch points to the power of the visceral, and the inherent struggle communicating "invisible" environmental changes, like ocean chemsitry changes, and in some ways, even climate. Sure, coral bleaching is visceral, but it is also foreign to most North Americans, and the causes of bleaching are invisible. But garbage? People can all relate to garbage. You can see it and smell it. Garbage is also a good metaphor; the ocean is literally our dumping ground.

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