The ocean is a major player in determining global climate, partly because they regulate the amount of CO2in the atmosphere, and hence, strongly influence the greenhouse effect. However, since anthropogenic CO2 has altered the natural carbon cycle, a potential mitigation is to stimulate the ocean’s uptake of CO2. Ocean iron fertilization (OIF) is a particular method that has received much attention within the scientific community. Naqvi and Smetacek (2011) discussed previous OIF hypotheses and experiments, and analyzed results. They then addressed opposition to OIF and stated common arguments against the technique. Threats to OIF research were also discussed. Naqvi and Smetacek addressed their own proposal for an OIF experiment- LOHAFEX. Naqvi and Smetacek stated that their research allowed for significant findings about plankton ecology and that restrictions on it prevented important information from being discovered. The authors opposed commercialization of OIF and concluded that OIF research should not be highly regulated. —Michela Isono
Naqvi. S., Smetacek, V., 2011. Ocean Iron Fertilization. A Planet For Life 1, 197–205.
The Ocean’s Role in Combating Climate Change and Supporting Experiments
The oceans’ ability to absorb CO2is very important to combat global warming; oceans hold approximately 50 times more CO2 than the atmosphere. The amount of CO2 in the atmosphere now equals a third of the total carbon in all terrestrial vegetation, equivalent to about 100 parts per million/volume (ppm/v) higher than in preindustrial times. The authors support research for geoengineering methods to decrease the amount of CO2 in the atmosphere, particularly, the use of the biological carbon pump in the ocean. They introduced trace amounts of iron to nutrient-rich regions of the ocean in order to stimulate the growth of phytoplankton (microscopic organisms that consume carbon dioxide and release oxygen). Iron is used because it is the limiting nutrient for phytoplankton growth in some parts of the ocean. Phytoplankton die and sink after a bloom. Carbon is thus transferred to the deep ocean and sea floor.
Ocean iron fertilization experiments were first used in the mid 1900s to analyze ecological and biogeochemical phenomena in the ocean, explaining the inconsistency of low phytoplankton efficiency in three large, nutrient-rich regions: the sub-arctic Pacific, the Equatorial Pacific, and the Southern Ocean at both tropical and polar latitudes. It was hypothesized that low phytoplankton growth and productivity was due to low supply of iron. Additionally, in the last Ice Age in northern Europe and North America, the concentration of CO2 in the atmosphere was 100 ppm/v lower than that of the previous century. A large increase of iron to northern Europe and North America during the ice age would have increased phytoplankton productivity and removed more CO2 in the deep ocean compared to the warm, wet periods that followed. The introduction of iron to ocean surfaces to increase the removal of CO2from the atmosphere was termed the “iron hypothesis.”
Numerous studies confirmed parts of the iron hypothesis in regions with sufficient nutrients but low-productive phytoplankton. The studies increased the growth of phytoplankton most of which were diatoms (a major group of algae and the most common type of photoplankton). These diatoms had a protective shell made of silica, and died and sank as a group. The European Iron Fertilization Experiment (EIFEX) was done to confirm this natural diatom process. The experiment took place in an oceanic eddy (circular current) with a closed core that was 100 km wide and 3,500 km deep; oceanic eddies are important because they supply major areas of biological and physical activity. Iron was added to the eddy and a large bloom occurred that had the most diatom species in the ocean’s surface layer. Many phytoplankton cells then grouped together and sank to the deep ocean. Even with many zooplankton (small invertebres) that consume diatoms, the feeding on the diatoms was unexpectedly low. This experiment confirmed the diatom’s natural process.
Previous OIF studies were conducted in low-productive oceanic regions located away from natural sources of iron. These studies investigated large, spiny and thick-shelled diatoms. In 2005, India and Germany conducted a joint OIF experiment called LOHAFEX. The experiment focused on a different diatom population that lived in the Southwest Atlantic part of the Antarctic Circumpolar Current. These diatoms were smaller in size, had thinner shells, and grew faster. They also died and sank as a group after they bloomed. This region had productive phytoplankton and a significant amount of iron in its coastal waters. A study that focused specifically on the distribution of this particular diatom species found the diatoms extended eastward about 10˚W. Other sediments left during the previous glacial period proved an eastward allocation that spanned the Atlantic sector. This suggested that these diatoms seized the carbon missing from glaciers from the Ice Ages.
The authors turned in the LOHAFEX proposals in 2006. After other scientists in India and Germany reviewed the proposal, the authors were granted ship access and the equivalent of $4 million in funds. Afterwards, The Alfred Wegenger Institute in Germany and India’s National Institute of Oceanography created a memorandum of understanding (MoU) for their shared experiment. The leaders of each institute signed the MoU in October 2007. Other scientists from institutions in Italy, Spain, the United Kingdom, France, and Chile also joined the team. In total, the LOHAFEX team included 49 scientists. The National Institute of Oceanography (NIO) held a two-week training course in January and February 2008 and a preparation practicum in April 2008 that trained the people who measured these processes. These training sessions were important because open ocean experiments provide crucial information for developing models of ocean ecosystem functioning that help forecast how climate change will affect oceans and oceans’ organisms.
Opposition to OIF
Naqvi and Smetacek acknowledged objections to OIF geoengineering. After the first successful OIF experiments in the mid-1990s, various companies publicized that they would use OIF to obtain carbon credits on the market through the Kyoto Protocol; The Kyoto Protocol is a set of rules to the United Nations Framework Convention on Climate Change (UNFCC) that combats global warming, and the UNFCC is an international environmental treaty that aims to achieve safe levels of greenhouse gas concentrations in the atmosphere. The media did not differentiate small-scale, scientific experiments and large-scale commercial enterprises. This caused a negative view of OIF within the public domain.
Other arguments against OIF were based on previous reports about heavy metal pollution (fertilizing the ocean with nitrogen and phosphorous) and eutrophication (excessive plant growth). The perceived consequences were damaged aquatic and terrestrial organisms, and lack of oxygen for local organisms, respectively. Additional concerns regarded animal deaths and human health resulting from worsened water quality and contaminated aquatic species. The authors confirmed these consequences. However, the authors did not validate the drawn comparison between heavy metal pollution and eutrophication (which consisted of constant, large doses of metals in coastal areas), with their idea (adding trace amounts of iron to the deep ocean). The authors argued that if the iron dose were small and sporadic it would not harm the environment.
The potential bloom of toxic species was another argument against OIF. The authors stated the majority of toxic species, dinoflagellates, usually arose in shallow waters and were absent in the open ocean. However, the authors stated that some toxic species, Pseudo-nitzchia, did arise in OIF experiments. These toxic species usually occurred in coastal upwelling regions. Negative effects to marine shellfish and animals were reported from the West and East Coasts of the United States and the province of Prince Edward Island in Canada. However, other accounts of toxic algal blooms in the Gulf of Mexico and the coast of Portugal did not have negative affects of marine mammals and birds. The authors stated further experiments were necessary to test the risks of toxic species in OIF conditions.
Threats to OIF Research and the LOHAFEX Experiment
The publicized statements of corporate OIF plans stimulated environmental groups, governmental organizations, and nongovernmental organizations to oppose implementing OIF plans. Consequently, in May 2008, the Conference of the Parties to the Convention of Biological Diversity (CBD) necessitated extensive prior research before implementing any ocean fertilization techniques. They also demanded that the techniques be heavily controlled. The CBD statement advised parties to follow the decision of the London Convention on the Prevention of Marine Pollution by Dumping Wastes and Other Matter. This CBD statement was very controversial. Thus, the Contracting parties to the London Convention and the London Protocol discussed ocean fertilization. In October 2008, they ruled that ocean fertilization is only permitted for scientific research, and each proposal will be reviewed on a case-by-case basis. The authors thus decided to proceed with their LOHAFEX experiment.
The LOHAFEX Experiment and Results
Despite significant protest from multiple German NGOs, the LOHAFEX experiment was deemed acceptable by the German government. The team received permission to use an oceanic eddy with a closed core in the Southwest Atlantic waters. Ten tons of granular iron sulphates dissolved in seawater were introduced to a 300 square kilometer area. The authors noted the amount of iron used was within the natural amount of iron in unpolluted coastal waters. The team tracked the iron-fertilized region for 38 days. The fertilized region remained within the eddy for 23 days and was then expelled. The region then spread and dissolved.
The results of the LOHAFEX experiment showed different results than the aforementioned OIF experiments conducted in regions with low productive phytoplankton. Six important results were found: 1) diatoms were absent and phytoplankton biomass was composed mainly by small flagellates; 2) strong grazing by zooplankton prevented phytoplankton’s biomass from exceeding 1.7 milligrams of chlorophyll a per cubic meter (chlorophyll is critical for plants to obtain energy from light and measuring the amount of chlorophyll a is a good measure of phytoplankton biomass); 3) bacterial biomass was low despite primary productivity being doubled; 4) the uptake of CO2 was moderate; 5) small amounts of organic substance went to the deep ocean, and 6) iron fertilization did not effect the making of other greenhouse gases that destroy the ozone (carbon and halogen compounds).
Two important inferences were drawn from these results. The first was that introducing iron to iron-deficient regions in the Southern ocean does not increase the size of the phytoplankton bloom; grazers controlled the size. The second implication was that OIF’s ability to remove anthropogenic CO2 was lower than expected. The authors stated that more issues with OIF methods must be addressed. These issues encompassed the role of trace elements, the relationship between phytoplankton and zooplankton during time periods when zooplankton supply is lower, and the effect on the food chain with long-term OIF methods. The authors recognized the importance of OIF research for the discovery of important benefits. They believed commercialization and misplaced concerns would limit scientific research. The authors opposed OIF commercialization and stated that future research should be funded by carbon taxes instead of a carbon credit market. They concluded that scientific research should not be highly regulated.