Ocean Iron Fertilization

Policy recommendation

Trials of ocean iron fertilization (OIF) should urgently be carried out to learn whether it could be a significant tool to permanently sequester atmospheric carbon. Experiments must be carefully designed and executed to maximize the chance of success, avoid risk, provide the highest quality data, and avoid foreseeable methodological oversights. Journalists, environmental organizations, and government officials must be briefed on experiments in advance so they understand they are being carried out safely.

Why iron ocean fertilization?

For decades, scientists have known that fertilizing ocean water with iron increases the growth and reproduction of phytoplankton and other life. It is well understood that the oceans store large amounts of carbon in many different forms. Some carbon is stored semi-permanently, for centuries or even millennia, in ocean waters in several different forms. Some carbon is stored permanently, at the ocean floor through several processes. It is not known what portion of carbon absorbed into oceans is permanently sequestered, and the share is probably very small.

Some scientists have suggested that OIF could remove excess atmospheric carbon dioxide and store it permanently and semi-permanently. The activist and author Peter Fiekowsky even has suggested it could sequester enough to return atmospheric CO2 to the historically safe level of 300 parts per million. Most, however, believe that OIF is not well enough understood to make such claims, and that it likely cannot sequester sufficiently large amounts of additional carbon and could have harmful effects.

Nevertheless, available data suggest that there is at least some chance that OIF could safely remove large amounts of CO2 from the atmosphere. Given how important such an accomplishment would be, this possibility must be investigated. Experiments must be conducted as soon as possible because cooling the planet over the next decade could prevent the world from reaching dangerous global warming tipping points that could be unleashed if global temperatures keep rising according to current trends.

Potential risks

Experiments with iron ocean fertilization must be designed to both avoid and learn more about potential risks. Potential risks include:

Ecosystem Disruption: Artificially altering the nutrient balance in marine ecosystems can lead to unintended consequences. The rapid growth of phytoplankton can disrupt existing food webs and harm species that are not adapted to such changes.

Harmful Algal Blooms: While the goal is to stimulate beneficial phytoplankton, OIF could inadvertently promote the growth of harmful algal species. These harmful algal blooms (HABs) can produce toxins that affect marine life, human health, and fisheries.

Oxygen Depletion: When large amounts of phytoplankton die and decompose, it can lead to oxygen depletion in the water. This process, known as hypoxia, can create "dead zones" where most marine life cannot survive, leading to a loss of biodiversity.

Acidification: Increased phytoplankton activity can lead to higher levels of organic matter decomposition, which can release carbon dioxide and contribute to ocean acidification. This can further stress marine ecosystems, particularly organisms with calcium carbonate shells or skeletons.

Limited Understanding: The long-term impacts of OIF are not well understood. There are many unknowns about how such interventions might interact with complex marine systems over time, making it difficult to predict all potential outcomes.

Experiment design

To achieve the highest standards of safety and reliability, experiments on OIF must be meticulously planned and monitored. A robust experimental design should include detailed risk assessments, clearly defined objectives, and comprehensive baseline data collection. This foundation will help in distinguishing the effects of iron fertilization from natural variability. Deploying a range of sensors and autonomous vehicles can provide real-time data, allowing researchers to make adjustments as needed and ensure that the trials do not inadvertently cause harm to marine ecosystems.

While it is important to engage with the scientific community and regulatory bodies, there is a pressing need to move forward with large-scale experiments despite potential conservatism within the establishment. All attempts should be made to adhere to global standards and best practices, but an emphasis on the urgency of these studies is crucial. Transparent communication with the public and stakeholders remains essential. Regular updates and open access to research findings will foster trust and facilitate informed decision-making by policymakers and the public.

Post-experiment monitoring is as important as the trials themselves. Long-term observation of the fertilized areas is necessary to evaluate the durability of carbon sequestration and any delayed ecological impacts. This ongoing surveillance can provide critical insights into the effectiveness and sustainability of OIF as a carbon sequestration strategy. Additionally, it can help in identifying any unforeseen consequences, thereby contributing to the body of knowledge required to make informed decisions about the broader application of this technique.

Ultimately, the goal of these carefully designed and executed experiments is to gather comprehensive, high-quality data that can inform future policies and strategies for mitigating climate change. By thoroughly understanding the potential benefits and risks of OIF, scientists and policymakers can make evidence-based decisions on its viability as a tool for atmospheric carbon reduction. This approach ensures that any actions taken are grounded in rigorous scientific research, thereby maximizing the likelihood of successful and safe carbon sequestration.

Public communication

The history of OIF experiments is marked by significant public scrutiny and controversy. In past instances, such as the LOHAFEX and the Haida Salmon Restoration Corporation experiments, public and environmental organizations raised concerns about the potential risks and unintended consequences of OIF. These concerns were often exacerbated by a lack of transparent communication and inadequate stakeholder engagement, leading to widespread public blowback and calls for regulatory intervention.

To prevent such backlash and foster a supportive environment for future experiments, it is crucial to proactively engage journalists, environmental organizations, and government officials well in advance of any planned OIF activities. Detailed briefings should be provided to these key stakeholders, explaining the scientific rationale, safety measures, and expected outcomes of the experiments. Clear and transparent communication will help demystify the process, address any misconceptions, and build public trust in the research efforts.

Additionally, establishing open channels for dialogue and feedback with these groups can help identify and address concerns before they escalate. By involving stakeholders in the planning and execution phases, researchers can ensure that the experiments are carried out responsibly and with broad societal support. This collaborative approach will not only enhance the credibility and acceptance of OIF research but also contribute to more robust and inclusive decision-making processes.

Understanding iron ocean fertilization

Oceans, life and photosynthesis

The ocean is home to every branch of life. Only 1% of the earth’s life (by mass) lives in the oceans. Yet approximately half of all photosynthesis in the world takes place in the oceans.Phytoplankton are responsible for the vast majority of photosynthesis in the ocean and almost half in the world. Photosynthesis in the ocean removes CO2 from water. This indirectly removes CO2 from the atmosphere, since CO2 in the surface waters is replaced from the atmosphere through the process of diffusion. Photosynthesis uses carbon from CO2 as the basic building block of life and energy storage. Photosynthesis releases oxygen into the oceans and indirectly back into the atmosphere. Photosynthesis is essential for maintaining stable levels of oxygen in the atmosphere and the world’s water. Photosynthesis only occurs in the top layer of ocean water that light penetrates — called the euphotic zone. The depth of the euphotic zone varies with water clarity and other factors.

Despite making up a tiny percentage of the world’s total biomass, phytoplankton are responsible for drawing down a huge share of the new CO2 released into the atmosphere by ecosystems and human activities. It can seem unbelievable that such a small amount of biomass can really be responsible for processing such huge amounts of CO2 through photosynthesis. This is explained by the short life cycles of phytoplankton and their incredible efficiency as photosynthesizers. Phytoplankton are the base of the food chain that feeds most other life in the oceans — so their mass is constantly being absorbed into higher trophic levels and quickly decomposing due to their short life cycles.

The carbon cycle and carbon export

The vast majority of the carbon that makes up life is released back into the water, and indirectly into the atmosphere. This happens primarily through the related processes of respiration and decomposition. Carbon from ocean biomass that isn’t permanently or semi-permanently sequestered in the ways described below remains active in the carbon cycle, being released as a gas during decomposition of dead organisms, or going into new living biomass. OIF is said to increase biomass in the oceans — by increasing phytoplankton and all the life at higher trophic levels that depend on phytoplankton. This raises the idea that perhaps more carbon could be stored in the oceans as a result of an overall increase in biomass. It is not known how much additional carbon can be stored by a total increase in the living biomass of the oceans — but all the oceans currently only contain about 6 GtC in the form of living biomass, whereas more than 190 GtC must be sequestered to get back to historically safe atmospheric CO2 levels. Therefore, increasing the total stock of ocean biomass is not a viable pathway to sequestering significant levels of carbon.

Some carbon is sequestered semi-permanently when it is “exported” to the lower levels of the ocean. This happens when dead organisms and fecal matter sink instead of decomposing in the top layers of the oceans — a process sometimes referred to as “marine snow.” Carbon in that form is known as particulate organic carbon (POC). Eventually POC is decomposed into CO2 and carbonic acids. In those forms, carbon can remain very deep in the oceans for hundreds — even thousands — of years before finally being resurfaced by ocean currents. It remains unknown how much carbon from the top layer of the ocean is sequestered for a long period in the depths of the ocean. Many different poorly understood or unknown factors influence the rate of carbon export to the lower depths of the ocean. It is also unknown how much additional carbon could be safely added to the deep oceans. Additional CO2 and carbonic acids raise the acidity level of the ocean and can cause other problems.

Carbon from marine snow and other falling biomass and POC can be sequestered permanently when it is buried and remains under the ocean floor, stored in shells formed by living creatures that are ultimately buried, or in other ways. Though it has been studied for decades, it is still unclear how much of the carbon in ocean biomass is permanently sequestered in these ways. Some estimates are as low as 1%, but that rate is probably much higher under particular conditions and locations. Different types of currents, nutrient availability, sunlight, and probably many unknown factors influence the rate of permanent sequestration of carbon from ocean biomass.

Iron and other nutrients

Some parts of the ocean hold far more plant and animal life than other parts. The primary reason for denser concentrations of life in some parts of the ocean is access to nutrients. In most places, iron is a unique missing nutrient whose scarcity limits the growth and reproduction of life at every level of the food chain. The population size and total mass of many types of organisms increase even when iron is the only nutrient to be increased. When iron levels in the ocean increase, many forms of life in the ocean grow and reproduce to increase their total collective mass.

Iron availability for oceanic organisms in many locations can vary dramatically over time — even up to a factor of five. When iron availability in a region increases, the quantity of photosynthesis and total biomass can increase rapidly and dramatically. Populations of phytoplankton have been observed to double in mass in a single day.

Iron that settles on the surfaces of oceans comes in many forms, from many sources, with different levels of usefulness for life.

Other nutrients — such as phosphorus, silica and many others — have a significant impact on the reproduction and growth of life in oceans. If fertilization with iron alone can not accomplish desired levels of carbon sequestration, it’s possible that better results could be achieved by fertilization with iron plus other nutrients.

Iron fertilization

[Over the past several decades, scientists have conducted many experiments in Iron Ocean Fertilization. Initial experiments demonstrated that adding iron to iron-deficient ocean regions could stimulate significant phytoplankton blooms. These blooms were characterized by increased chlorophyll concentrations, indicating higher photosynthetic activity.

The addition of iron successfully triggered phytoplankton blooms in several experiments, confirming the hypothesis that iron is a limiting nutrient in certain oceanic regions. The response was most noticeable in high-nutrient, low-chlorophyll (HNLC) areas, where the availability of other nutrients was not a limiting factor.](facts/iron-ocean-fertilization-phytoplankton-growth.md)

While initial results were promising in terms of phytoplankton growth, the effectiveness of OIF in sequestering carbon was more complex. It was found that only a small fraction of the carbon fixed by the phytoplankton was transported to the deep ocean. The vast bulk of the new organic matter decomposed in the upper layers of the ocean, releasing CO2 back into the oceans and indirectly to the atmosphere. The actual amount of carbon sequestration was therefore lower than initially hoped.

One finding from these experiments was the potentially significant role of diatoms in carbon export, a group of phytoplankton that form silica-based shells. Diatoms dominated iron-induced blooms in some experiments, and their heavy, silica-rich shells facilitated the sinking of organic carbon to the ocean floor. This enhanced the carbon sequestration potential compared to other types of phytoplankton. However, the availability of silica is a limiting factor influencing the extent of diatom growth and the overall effectiveness of iron fertilization.

Experiments over the years have highlighted potential ecological impacts, including alterations to local food webs and the risk of harmful algal blooms. These unintended consequences underscored the need for careful consideration of the broader ecological effects of OIF.

Conclusion

Overall, IOF experiments have provided valuable insights into the potential and limitations of iron fertilization as a strategy for carbon sequestration. While the addition of iron can enhance phytoplankton growth and has the potential to sequester carbon, the effectiveness is limited by factors such as the remineralization of organic matter and the availability of other nutrients like silica. The dominance of diatoms in these blooms offered some promise for increased carbon sequestration, but the broader environmental impacts and complexities suggest that OIF is not a straightforward solution to climate change. Future research continues to explore these dynamics, aiming to balance carbon sequestration goals with ecological sustainability.