Comment & Debate
Iron fertilization is the intentional introduction of iron to the upper ocean to increase the marine food chain and to sequester carbon dioxide from the atmosphere. It involves encouraging the growth of marine phytoplankton blooms by physically distributing microscopic iron particles in otherwise nutrient-rich, but iron-deficient blue ocean waters. An increasing number of ocean labs, scientists and businesses are exploring it as a means to revive declining plankton populations, restore healthy levels of marine productivity and/or sequester millions of tons of CO2 to slow down global warming. Since 1993, ten international research teams have completed relatively small-scale ocean trials demonstrating the effect. In the context of strategies to combat global warming, iron fertilization is considered a form of geoengineering and mitigation. That is, it attempts to sequester and reduce carbon dioxide directly from the atmosphere. Clean-energy approaches attempt to reduce new additions of carbon dioxide and other greenhouse gas emissions into the atmosphere, so are a form of prevention. There are many questions surrounding iron fertilization that help frame the debate: Does iron fertilization and growing phytoplankton blooms help sequester significant quantities of carbon dioxide? Is it significant enough to have an impact in reducing global greenhouse gases and slowing global warming? Is this approach necessary at this stage in global warming? Are alternative forms of prevention, such as clean-energy, insufficient? Are phytoplankton populations above or below their ordinary levels currently? Is global warming killing-off phytoplankton, and would this contribute in a “positive feedback loop” to an acceleration of global warming? If so, is this further justification for iron fertilization? Are there negative effects on ocean ecosystems? Does iron fertilization risk growing harmful “red tides”, depleting deep water oxygen levels, and damaging fisheries? If so, are these potential costs worth trading for the benefits of combating global warming (an environmental threat in its own right)? How should the precautionary principle be applied to iron fertilization? What principles of environmental justice are involved in this debate? Finally, is iron fertilization economically feasible?
John Martin, former director of the Moss Landing Marine Laboratory, said in 1988, “Give me half a tanker of iron, and I’ll give you an ice age”. This famous statement has highlighted the power of iron fertilization in spawning massive algae blooms to draw large quantities of C02 from the atmosphere, in the process of photosynthesis, reducing the greenhouse gas effect and helping cool the planet.
All the main solutions to global warming entail cutting greenhouse gas emissions from future energy production. Yet, this does not reduce the amount of C02 currently in the atmosphere, nor does it promise to end C02 emissions any time soon. And, yet, global warming is occurring now from the existing quantities of C02 in the atmosphere. In other words, all plans to cut future emissions will not help actually reverse the current trajectory of global warming. The only real solution is to attempt to directly remove greenhouse gases from the atmosphere. Iron fertilization and algae blooms offer this kind of real solution to global warming, actually helping reverse it.
There is a good chance that global warming is irreversible. Global warming is already occurring and there are no plans toreduce greenhouse gases that are already in the atmosphere. Greenhouse gas levels will continue to rise, despite reductions in new emissions. Geoengineering, therefore, is the likely last resort.
While ocean science does traditionally define “sequestration” in terms of sea floor sediment that is isolated from the atmosphere for millions of years, modern climate scientists and Kyoto Protocol policy makers, however, define sequestration in much shorter time frames. They recognize trees and even grasslands, for instance, as important carbon sinks. Forest biomass only sequesters carbon for decades, but carbon that sinks below the marine thermocline (100~200 meters) is effectively removed from the atmosphere for hundreds or thousands of years, whether it is remineralized or not. Since deep ocean currents take so long to resurface, their carbon content is effectively “sequestered” by any terrestrial criterion in use today.
Timing – none of the ocean trials had enough boat time to monitor their blooms for more than 27 days, while blooms generally last 60~90 days; Scale – most trials used less than 1000 kg of iron and thus created small blooms that were quickly devoured by opportunistic zooplankton, krill and fish; Academic conservatism – with limited data sets, scientists have not been willing to (understandably) extrapolate upon their findings.
“Although fertilization can stimulate the growth of plankton and draw down atmospheric carbon dioxide, scientists do not know whether it would be effective in permanently keeping the carbon dioxide sequestered in the oceans.”
“With the scientific discovery that phytoplankton growth can be stimulated by the addition of iron to HNLC waters, some have proposed that the ‘biological pump’ could be enhanced by fertilizing the oceans with iron, as a way of drawing down more carbon dioxide from the atmosphere into the oceans and, in so doing, helping mitigate climate change. However, such proposals are founded on an incomplete understanding and highly simplified interpretation of current scientific knowledge. They have not taken properly into account the results of the 12 mesoscale iron enrichment scientific studies carried out to date which suggest that the amount of carbon sequestered in this way would be very small, nor the fundamental influence of hydrodynamics and large uncertainties and indeterminacies in ecosystem response which those studies highlight.”
“Beyond the inefficiency of carbon sequestration, iron fertilization would likely cause other changes “downstream” of the ocean patches where iron was added. The huge green phytoplankton blooms would take up not just iron but other nutrients, too—nitrate, phosphate, and silica—essentially depleting nearby waters of the building blocks needed for plankton growth.
“You might make some of the ocean greener by iron enrichment, but you’re going to make a lot of the ocean bluer,” said Robert Anderson, senior scholar at Lamont-Doherty Earth Observatory.”
“There is a risk that iron fertilization could result in increased production of nitrous oxide, a greenhouse gas far more powerful than carbon dioxide. It is of great concern that one modelling study predicted that any benefits of carbon sequestration by commercial iron fertilization could be outweighed by nitrous oxide production. In two mesoscale studies which tested for the production of nitrous oxide, one found a small but significant increase in nitrous oxide while the other did not detect the gas.”
Some ocean trials did indeed report remarkable results. According to IronEx II reports, their thousand kilogram iron contribution to the equatorial Pacific generated a carbonaceous biomass equivalent to one hundred full-grown redwoods within the first two weeks. Researchers on Wegener Institute’s 2004 Eifex experiment recorded carbon dioxide to iron fixation ratios of nearly 300,000 to 1. Current estimates of the amount of iron required to restore all the lost plankton and sequester 3 gigatons/year of CO2 range widely, from approximately two hundred thousand tons/year to over 4 million tons/year. Even in the latter worst case scenario, this only represents about 16 supertanker loads of iron and a projected cost of less than €20 billion ($27 Billion). Considering EU penalties for Kyoto non-compliance will reach €100/ton CO2e ($135/ton CO2e) in 2010 and the annual value of the global carbon credit market is projected to exceed €1 trillion by 2012, even the most conservative estimate still portrays a very feasible and inexpensive strategy to offset half of all industrial emissions.
“Twelve oceanographic expeditions were carried out between 1993 and 2005 is the North Pacific, the Equatorial Pacific and the Southern Ocean to test the iron fertilization hypothesis. However, as pointed out by Hein de Baar, from the Netherlands Institut voor Onderzoek der Zee (NIOZ, Texel, The Netherlands), today after all those experiments we know that they are many losses and that this manipulation is not a real efficient way to capture and store CO2 into the deep ocean. Much more iron is needed that had originally been suggested for algae to bring down a certain amount of CO2 from the atmosphere.”
“such schemes would be virtually impossible to carry out in practice because of the colossal areas that would have to be fertilized to result in significant atmospheric carbon removal.”
“Verifying the quantity of carbon sequestered from iron fertilization is also likely to be difficult (if not impossible) because of the large spatial and temporal scales involved.”
“While it is true that OIF produces ecological changes, as we will show, there is no a priori evidence from literature that OIF experiments projects might result in widespread deleterious ecological changes. The preponderance of evidence suggests that OIF experimentation and study, even if done at scales of 200 x 200 km, will not harm ecosystems.”
Iron fertilization main be a central solution to the greatest modern environmental crisis; global warming. While it may cause some other problems in ocean ecosystems, these problems are outweighed by the environmental priority of combating global warming.
Algae blooms last between 90 and 120 days. They never take root in an ocean ecosystem, so cannot permanently and dramatically alter or harm an ecosystem.
Algae are food for fish such as krill, which are food for larger fish, which are food for even larger fish. In this way, algae blooms can help feed and grow fisheries and cetacean populations. This is a compelling human interests, given the extent to which fisheries have been depleted in the last century.
Depending upon the composition and timing of delivery, iron infusions could preferentially favor certain species and alter surface ecosystems to unknown effect. Population explosions of jellyfish, disturbance of the food chain with a huge impact on whale populations or fisheries are cited as potential dangers.
“Iron fertilization results in other essential nutrients, such as nitrates, phosphates ad silicates, being used up as the phytoplankton bloom progresses. Consequently, this could result in a reduction of these nutrients down-current from an iron- fertilized area. In turn, a lack of nutrients would cause a negative impact on phytoplankton down-current resulting in a reduction in overall biological productivity. This would be likely to have a knock-on negative impact on all other marine life because phytoplankton underpin the marine food web. Indeed, because of this phenomenon, modeling studies have predicted that commercial-scale iron fertilization of the oceans could have a significant detrimental impact on important fisheries.”
Iron fertilization and algae blooms can increase particulate organic export and remineralization, reducing oxygen levels, which negatively impacts many marine organisms.
Iron fertilization would help to reverse what some believe to be a decline in phytoplankton. One study (Gregg and Conkright, 2002) reported a decline in ocean phytoplankton productivity between the period 1979–1986 and 1997–2000. If phytoplankton populations are down by natural standards, there should be not environmental argument against helping these populations rebuild. And, it could be argued that the decline of these phytoplankton are partly responsible for global warming, since it would reduce the capture of C02 in the process of photosynthesis.
“The microscopic plants that underpin all life in the oceans are likely to be destroyed by global warming, a study has found…Scientists have discovered a way that the vital plankton of the oceans can be starved of nutrients as a result of the seas getting warmer. They believe the findings have catastrophic implications for the entire marine habitat, which ultimately relies on plankton at the base of the food chain.”
One study (Antoine et al., 2005) found a 22% increase of phytoplankton populations between 1979–1986 and 1998–2002. Gregg et al. 2005 also reported a recent increase in phytoplankton. If phytoplankton are actually up compared to natural averages, it cannot be argued that iron fertilization can help re-stabilize the natural size of phytoplankton populations. In fact, iron fertilization would only accentuate the problem of currently over-sized phytoplankton populations.
“Global warming of the surface layers of the oceans reduces the upward transport of nutrients. Computer simulations predict that plankton growth will become unstable when the supply of nutrients is reduced. This may have a negative impact on the food chains of the oceans and on uptake of the greenhouse gas carbon dioxide into the oceans. Scientists of the Universiteit van Amsterdam and CWI (the Netherlands) and the University of Hawaii (USA) presented their results in Nature of 19 January 2006.”
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