Nature: Ocean fertilization for geoengineering “should be abandoned”

In the face of seemingly accelerating climate change, some have proposed tackling the problem with geoengineering: intentionally altering the planet’s physical or biological systems to counteract global warming. One such strategy “” fertilizing the oceans with iron to stimulate phytoplankton blooms, absorb carbon dioxide from the atmosphere and export carbon to the deep sea “” should be abandoned.

So begins a recent Nature opinion piece, “Ocean fertilization: Time to move on” (subs. req’d, excerpted below) by four researchers and oceanographers.

The more you know about geo-engineering, the less sense it makes (see Science: “Optimism about a geoengineered ‘easy way out’ should be tempered by examination of currently observed climate changes”).  The most “plausible” approach, massive aerosol injection, has potentially catastrophic impacts of its own and can’t possibly substitute for the most aggressive mitigation — see Caldeira calls the vision of Lomborg’s Climate Consensus “a dystopic world out of a science fiction story.” And for the deniers, geo-engineering is mostly just a ploy — see British coal industry flack pushes geo-engineering “ploy” to give politicians “viable reason to do nothing” about global warming.

Geo-engineering is a “smoke and mirrors solution,” though most people understand that the “mirrors” strategy is prohibitively expensive and impractical.  One of the few remaining non-aerosol strategies still taken seriously by some is ocean fertilization.  This Nature piece explains why it should be abandoned:

It is already commonly accepted that ocean iron fertilization should not be rushed into as a mitigation strategy. The Intergovernmental Panel on Climate Change regards it as supported by neither appropriate assessment of environmental side effects nor a clear institutional framework for implementation. Similarly, last year, two United Nations conventions passed resolutions restricting large-scale ocean iron fertilization activities, citing concerns about the environmental risks and lack of a scientific basis on which to justify such activities “” concerns that have been recognized for some time. A Royal Society report released this month emphasized that the technique has a relatively small capacity to absorb carbon, and comes with “probably deleterious ecological consequences”.

Yet concerns about the profound consequences of global climate change have led to calls (see, for example, K. O. Buesseler et al. Science 319, 162; 2008) for field studies of iron fertilization on larger and longer scales. Although we agree that the kinds of experiments being promoted have more to teach us about ocean processes, we argue that they will not resolve any remaining debate about the risks of iron fertilization for geoengineering. Engaging in experiments with the explicit purpose of assessing iron fertilization for geoengineering is both unnecessary and potentially counterproductive, because it diverts scientific resources and encourages what we see as inappropriate commercial interest in the scheme.

Global impact

The intended effect of ocean iron fertilization for geoengineering is to significantly disrupt marine ecosystems. The explicit goal is to stimulate blooms of relatively large phytoplankton that are usually not abundant, because carbon produced by such species is more likely to sink eventually to the deep ocean. This shift at the base of the food web would propagate throughout the ocean ecosystem in unpredictable ways. Moreover, nutrients such as nitrogen and phosphorus would sink along with the carbon, altering biogeochemical and ecological relationships throughout the system. Some models predict that ocean fertilization on a global scale would result in large regions of the ocean being starved of oxygen, dramatically affecting marine organisms from microbes to fish. Ecological disruption is the very mechanism by which iron fertilization would sequester carbon.

The specific effects of global-scale ocean fertilization are hard to predict, because the ocean’s response is dependant on the scale at which such fertilization is done. Small-scale experiments are inherently inadequate to verify model predictions of the long-term side effects of global fertilization. Large-scale alteration of the ocean would be needed to resolve fundamental uncertainties about environmental risks.

Ocean fertilization for climate mitigation would have to be widespread and cumulative over decades. Thus, properly field testing its geoengineering potential would entail fertilizing and sampling an enormous swath of ocean. Assessment would be needed for between decades and a century or so to demonstrate sequestration, and to document the downstream effects on ecosystem productivity “” “nutrient robbing” as described in the Royal Society report “” and oxygen depletion. Such a test would have to be implemented against the background of a dynamic ocean that would remain exposed to unprecedented climate change, making the impacts of iron fertilization difficult to extract from other ongoing effects. In such a global experiment, there could be no ‘control patch’.

Given that the efficacy and indirect effects of ocean fertilization for geoengineering cannot be tested directly without altering the ocean on unprecedented scales, we must resort to using global-ecosystem models to predict its promise and pitfalls. Many modelling analyses have shown that iron fertilization cannot reduce atmospheric CO2 enough to significantly alter the course of climate change. A model published in 2008 (K. Zahariev et al. Prog. Oceanogr. 77, 56-82; 2008), which is as convincing as any available, found that even if the entire Southern Ocean were fertilized forever with iron sufficient to eliminate its limitation of phytoplankton production, less than 1 gigatonne of carbon a year of CO2 of probable future emissions (currently about 8 gigatonnes a year) would be sequestered, and that amount for only a few years at best. This level of effort is simply not going to happen.

We think the idea of geoengineering by iron fertilization persists because of the blurry line between it and small-scale ocean fertilization experiments that address specific hypotheses.

The original goal of iron fertilization experiments was to answer fundamental questions about how iron and carbon are used and cycled in marine ecosystems. They began with a project called IronEx I in 1993. Since then, 11 experiments have been conducted in regions of the equatorial Pacific, subarctic Pacific, and Southern Ocean that have high levels of most nutrients but a relatively low phytoplankton biomass. The experiments confirmed the testable hypothesis that iron is the crucial limiting nutrient in these regions, and they provided insights into plankton community dynamics. They were conducted on a relatively small scale (less than 300 square kilometres) and over relatively short periods of time (less than 40 days), and had ephemeral effects on surface ocean ecosystems. These experiments fuelled the idea that iron fertilization, scaled up, might be used for geoengineering “” even though they were not designed to investigate that possibility. This in turn prompted commercial interest in fertilizing the ocean to sell ‘carbon credits’.

Setting rules

In response to concerns about the ecological impact of large-scale commercial iron fertilization, the UN Convention on Biological Diversity issued a decision in May 2008 requesting member states to restrict ocean iron fertilization activities, with the exception of small-scale studies. Several months later, the London Convention on Marine Pollution issued a resolution stating that, given the present state of knowledge, ocean fertilization activities other than “legitimate scientific research” should not be allowed. These recommendations are a good start, but they are subject to interpretation. They do not resolve the blurred line between scientific hypothesis testing, and experiments focused on demonstrating geoengineering potential.

In January this year, for example, an experiment called LOHAFEX, which was designed to fertilize a small patch of the Southern Ocean with iron sulphate, was delayed for two weeks by the German government while it dealt with accusations from various environmental groups. The charge was that LOHAFEX was a dangerous ‘geoengineering project’ that violated the recent UN restrictions. It was allowed to proceed, after the scientists submitted environmental impact statements and the German government determined that it fell within UN regulations. But the episode illustrates the persistent ambiguity that surrounds these types of experiments.

It is time to disentangle the science of small-scale ocean fertilization from geoengineering. In our view, small-scale projects addressing testable hypotheses should proceed unimpeded by unnecessary controversy or regulation, whereas larger projects aimed at exploring the geoengineering potential of ocean fertilization should not be allowed, as they cannot resolve crucial issues about this mitigation strategy. Differentiating between these two types of experiments requires regulatory clarity.

Working groups from the London convention met in February 2009 to develop an assessment framework for ocean fertilization that will define what constitutes “legitimate scientific research” under their rules. The framework drafted at that meeting requested rigorous environmental risk assessments and mandated that all legitimate research must be driven by predefined hypotheses. The scientific group of the London convention has also started the process of defining the parameters for assessing the environmental impact of small-scale iron fertilization. Although the details, scope and enforcement mechanisms of these provisions are yet to be developed, this type of structured framework could help to avoid the kind of controversy that surrounded LOHAFEX.

Such exacting regulation is particularly important given the continuing interest in commercial iron fertilization for the sale of carbon offset credits. CLIMOS, a company based in San Francisco, California, has plans to conduct its first moderate-scale (40,000 square kilometres) ‘demonstration experiment’ in the Southern Ocean. Although it remains unclear where, when or if actual commercial iron fertilization might eventually take place, CLIMOS has attracted substantial initial investment on the prospect of selling carbon offsets from activities such as iron fertilization activities. CLIMOS has publicly agreed that all ocean iron fertilization activities should proceed only where there is an adequate scientific basis to justify them, and has promised to obtain any necessary permits. But there remains a lack of clarity over what might constitute an adequate scientific basis for such activities, given the scale-dependency of the ecosystem response to fertilization.

As for producing ‘carbon credits’ from experimental studies at any scale, the Kyoto Protocol’s Clean Development Mechanism does not recognize ocean fertilization as a way to create carbon credits for regulated international trade. Thus, carbon credits generated from such activities, however they might be quantified, would presumably have to be sold on the voluntary carbon market. The London convention process cannot regulate the generation of carbon credits, but it could determine that experiments that are used to generate credits would not be considered ‘legitimate scientific experiments’. The London convention has not yet addressed this issue. Given continued commercial interest in conducting moderate-scale demonstration experiments, which may or may not be considered ‘legitimate scientific experiments’, it seems essential to answer this question explicitly.

We already know enough about how ocean systems function to say that iron fertilization on large scales will be disruptive to ocean ecosystems and is unlikely to be effective for climate mitigation. Continuing to justify small-scale iron fertilization experiments in the context of global-scale geoengineering distorts the focus of oceanographic science, and encourages for-profit companies to continue pursuit of this strategy. It is time to move on.


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18 Responses to Nature: Ocean fertilization for geoengineering “should be abandoned”

  1. ecostew says:

    GAO Report:
    The GAO report specifically recommends that Congress consider biofuels’ impact on soil, air, water and wildlife, something that goes beyond the 2007 Energy Security and Independence Act, which sets targets for biofuels production. The law currently defines a biofuel based only on its greenhouse gas emissions, stipulating that a conventional biofuel like corn-based ethanol must produce 20 percent less greenhouse gasses compared with petroleum.

  2. BBHY says:

    So far we have put almost no effort at all into CO2 emissions reduction, and there is a huge amount of reductions possible with only a small effort.

    Ok, we need a little more than new light bulbs, but opponents (and some proponents) talk like we have to go back living in the 18th century.

    It would actually take relatively minor changes to our industries and improvements in efficiency with minimal impact on our lifestyles to far surpass the current 2020 reduction targets.

    Instead people propose these massive mitigation efforts that would be very expensive and extremely risky, and the only so-called advantage I can see is that we get to keep our coal plants with all of the other pollution and environmental problems they cause.

    I don’t get it.

  3. Rick Covert says:

    Will iron fertilization of the oceans for carbon credits based on no scientific basis as a way of generating the sale of carbon credits gain traction? Only if Wall Street has its way.

  4. I think that any mention of mimicking volcanic cooling ought to always be accompanied by the qualification that it does nothing for the other head of the two-headed CO2 monster, ocean acidification.

    Geoengineering via the oceans remains a candidate but, as the article does note, iron fertilization in iron-poor regions of ocean cannot scale up because it would soon deplete other nutrients.

    That still leaves two significant ocean possibilities, not discussed.
    1. Pumping up nutrients to mimick upwellings (that’s where the fisheries of the world are)could be done (see Lovelock’s ocean pipes in Nature 2008 or my chapter in GLOBAL FEVER: How to Treat Climate Change, Univ of Chicago Press 2008). This does not require exotic algal species but it still presumes that settling biomass below the thermocline (normally 11 GtC/yr) is the method for taking the CO2 production out of the wind-mixed layer and thus sequestering circulating excess carbon for a thousand years. Best suited for open ocean, it would have to be done with care in the shallower continental shelf waters to avoid hypoxia in the limited deeper waters of the shelf. However, this won’t do the job by itself as it would require fertilizing too much ocean to make a dent on our 600 GtC cleanup job to relieve both overheating and acidification.

    2. Building on up-pumps for nutrients would be mimicking natural ocean downwellings via down-pumps nearby. This sinks far more than just the debris and fecal pellets that are large enough to sink below the thermocline before decomposing into CO2 that soon returns to the air. One can now sink a huge amount of dissolved organic carbon (from dissolved feces and decomposition in the wind-mixed layer) and the algae, bacteria, and zooplankton–all in addition to that which sinks in the settle-out-only route utilized by iron fertilization.

    We haven’t exactly exhausted the negative-emissions possibilities. And we have the additional problem of a clean-up of CO2 to back out of the climate crisis. Mere emissions reduction, even to zero emissions, will not relieve things during our lifetimes–and we need that quick action to avoid more sudden climate shifts.

  5. Adam Sacks says:

    “It would actually take relatively minor changes to our industries and improvements in efficiency with minimal impact on our lifestyles to far surpass the current 2020 reduction targets.”

    Energy Smackdown (, a non-profit in the Boston area, has held friendly competitions among families and towns to see who could reduce household carbon emissions the most. The first year (it’s now in year four, I think), the winning family reduced by 63%, the “losing” family by “only” 51%. Most payback periods were relatively short.

    It’s not that difficult, but we have to tackle an insane, consumption crazy, nobody-can-tell-me-what-to-do culture.

  6. Leif says:

    An obvious “geoengineering project” should be jumped on as we speak, it has only good outcomes, approved by all and cheap to implment. REFORESTRATION.
    A second that even has the advantage of putting money in the pockets of at least the folks who already have money is energy efficency. Helps the poor as well, just not as fast.

  7. paulm says:

    CO2 concentrations have to come down, not just for temperate….

    Carbon-dioxide emissions are turning the waters of the Arctic Ocean into acid at an unprecedented rate,

    many regions around the north pole seawater is likely to reach corrosive levels within 10 years. The water will then start to dissolve the shells of mussels and other shellfish and cause major disruption to the food chain.

    “This is extremely worrying,” Professor Jean-Pierre Gattuso, of France’s Centre National de la Recherche Scientifique

  8. BBHY says:

    “And we have the additional problem of a clean-up of CO2 to back out of the climate crisis. Mere emissions reduction, even to zero emissions, will not relieve things during our lifetimes–and we need that quick action to avoid more sudden climate shifts.”

    Ok, I basically agree with you, but the global CO2 level is still going up dramatically, so it seems premature to start making elaborate plans at level reductions before making emissions reductions.

    It’s a bit like treating the patient’s burns while he’s still on fire, and the fire is actually accelerating. Step one should be to put our the fire, then work on mitigating the damage caused.

  9. Apropos REFORESTATION above (and Freeman Dyson’s similar point): the trees and other surface plants off the world total about 610 Gt of carbon. By 2030 we will have emitted about 600 GtC via fossil fuels and cement manufacture.

    Doubling forests, even if the land and water could somehow be spared from competing uses like feeding us all, there would still be a serious drawback: The climate forecast is for hotter summers, more droughts, and stronger winds. In some years, Amazonia already releases more CO2 than it absorbs.

    Planting trees does not qualify as either a climate fix or an emissions offset; trees are insufficiently secure against fire and rot.

  10. David B. Benson says:

    William H. Calvin (9) — Seriously consider

    Irrigated afforestation of the Sahara and Australian Outback to end global warming

    with, of course, wide fire breaks. When trees mature in about a century, convert to biochar and bury deeply.

  11. K Nockels says:

    #5 Adam I couldn’t agree more. When is enough, enough. How much is enough? It really is not hard to live within natures limits. If it is something you do because of love, love of our children, love of our Home (Earth), for the love of life, it really is not hard to do. We started nine years ago and it gets easier every year and more fun, finding new ways to conserve. Our kids call us the Consevringist People on planet earth. We aren’t of course but the thought is nice.

  12. Dorothy says:

    BBHY, when you write, “It’s a bit like treating the patient’s burns while he’s still on fire,” you are missing an important point. If you were a doctor in the emergency room, this is certainly something you wouldn’t want to try. But humanity’s problem is that we must concurrently treat for planetary burns and concurrently begin quickly to develop treatments for removal of excess CO2. Finding a safe way to do this will probably take a lot of time and certainly a lot of money, hence the rush.

    We have so much too much carbon in our atmosphere that we must do everything at once. We have to bring CO2 emissions to zero before our carbon budget runs out (as early as 2015) AND fund and develop methods remove excess carbon. How much excess carbon? Professor William describes its mass as the equivalent of four Mount Rainiers.
    I do agree with Joe and all the excellent comments on this post that the idea of ocean fertilization is a very bad one. To use a popular medical analogy, “first, do no harm.” But we have to do something and do it fast.

    An International Climate Conference on 4 degrees just took place:
    Some of the conclusions are truly frightening. If you click on this site, you can get abstracts, audio and visual of the presenters, among them Professor John Schellnhuber of the Potsdam Institute for Climate Impact.

    From the statement of the conference rationale, “Despite 17 years of negotiations since the 1992 Rio Earth Summit, global greenhouse gas emissions have continued to rise. Since 2000 the rates of annual emissions growth have increased at rates at the upper end of the IPCC scenarios, presenting the global community with a stark challenge: either instigate an immediate and radical reversal in existing emission trends or accept global temperature rises well beyond 4°.

    “The immediacy and scale of the reductions necessary to avoid anything below 4°C, and indeed the human and ecosystem implications of living with 4°C, are beyond anything we have been prepared to countenance. Understanding the implications of 4°C and higher temperatures is essential if global society is to make informed choices about the balance between “extreme” rates of mitigation and “extreme” impacts and adaptation costs.”

  13. Leif says:

    A recent study by a Russian scientist, (no link), hypothesized that mature forest help move rain inland. His feelings were that the increased surface area of the wet forest as opposed to just flat ground allowed more of the water to re-evaporate and fall again further inland than would be the case had the rain just fallen on the ground and be absorbed. This increased evaporation also serves to spread the moisture over far larger areas thus minimizing localized flooding. Think of the Amazon area recently, along with other intense floods thru out the world. Once I read the report it seamed like a “no brainer” to me.

  14. David B. Benson says:

    Leif (13) — That certainly works in the tropics. Not so sure for temperate zone forests.

  15. anders says:

    Iron fertilization problematical I agree, read an idea of using wave driven pumps to bring up nutrient rich deep water to surface where you have enough sunlight that the plankton can use the nutrients more interesting. We are not adding anything and the indications are that the natural pumps in many places are working less well as surface waters heated up.
    We need some way to remove CO2 from oceans as the pH getting dangerously low.

  16. Leif says:

    Anderes, 15. Here in the Pacific North West we have been having our own “dead zone” off the Washington and Oregon coast during the summers. I do not believe that this has been covered very well in the national media. The “cause” has not been established but appears to be shifting of the summer wind pattern not bringing the up-welling that is needed for circulation. This has had a detrimental effect on sea bird hatching and survival, as well as the salmon returns. All this is a new phenomena and lots of hair pulling. Killer whales that feed on king salmon have been dying. It is all very sad. I have fished the coast and the thought of putting wave pumps in a high enough density to amount to more than a fart in a gale of wind out there does not seam feasible.
    Not sure why I wrote this, perhaps just getting over whelmed by it all. So it goes…

  17. Leland Palmer says:

    [JR: This is important and it’s on my list, hopefully for this week.]

    Hi all-

    Don’t know if this has been covered here on Climate Progress, but it really is a kind of “smoking cannon” in the whole climate debate:

    NASA Ice Satellite Maps Profound Polar Thinning

    Researchers have used NASA’s Ice, Cloud and Land Elevation Satellite (ICESat) to compose the most comprehensive picture of changing glaciers along the coast of the Greenland and Antarctic ice sheets.

    The new elevation maps show that all latitudes of the Greenland ice sheet are affected by dynamic thinning — the loss of ice due to accelerated ice flow to the ocean. The maps also show surprising, extensive thinning in Antarctica, affecting the ice sheet far inland. The study, led by Hamish Pritchard of the British Antarctic Survey in Cambridge, England, was published September 24 in Nature.

    These changes in the Greenland and Antarctic ice sheets show rapid and continuing acceleration of glaciers in areas long known to be weak points in these ice sheets, and constitute evidence that warming is indeed occurring, and is a global phenomenon.

    We don’t have time to fool around.

    We need to nationalize the coal fired power plants, and convert them into enhanced efficiency biomass/biochar burning “carbon negative” power plants. Such power plants would combine oxyfuel combustion with an external gas turbine topping cycle, and would pay for their carbon capture and storage with increased combustion efficiency.

    Most coal fired power plants are located on major rivers or lakes to provide cooling water. These waterways constitute natural biomass or biochar transport networks, to bring these fuels to the power plants. We should also immediately start planting biomass plantations upstream from the coal fired power plants, on a massive scale, and then float biomass or biochar from these plantations down to the power plants on river barges.

    Download the CARMA (Carbon Monitoring for Action) power plant database into Google Earth to see visually where the power plants are, and see where the biomass resources are. The entire Mississippi basin, including especially the Ohio river, could be relatively easily turned into a giant carbon negative power project. Deep saline aquifers for deep injection of CO2 lie under most of these power plants, and pipelines for captured CO2 could be easily constructed for the rest.

    Time’s up. We’re out of time.

    Carbon neutral “green” sources of energy are good, but we need carbon negative power plants, we need all of the currently existing coal fired power plants to be transformed into carbon negative power plants, and we need them now.

    Of course we need “green” energy, and reforestation, and so on. But we need to start putting billions of tons of carbon per year back underground, too.

  18. DN says:

    A recent study by a Russian scientist, (no link), hypothesized that mature forest help move rain inland. His feelings were that the increased surface area of the wet forest as opposed to just flat ground allowed more of the water to re-evaporate and fall again further inland than would be the case had the rain just fallen on the ground and be absorbed. This increased evaporation also serves to spread the moisture over far larger areas thus minimizing localized flooding. Think of the Amazon area recently, along with other intense floods thru out the world. Once I read the report it seamed like a “no brainer” to me.