A group of scientists from the non-profit consortium Exploring Ocean Iron Solutions (ExOIS) is revisiting the controversial technique of ocean iron fertilization (OIF). This method, detailed in a recent paper in Frontiers in Climate, involves adding iron to a section of the northeastern Pacific Ocean.
The scientists aim to start this effort by 2026, and their goal is to promote the growth of phytoplankton, tiny marine plants that can absorb carbon dioxide (CO2) from the air. Ocean iron fertilization is based on the idea that iron is a critical nutrient for the growth of phytoplankton.
“There are many potential approaches to marine carbon dioxide removal (mCDR), of which ocean iron fertilization (OIF) has the longest history of study,” said the scientists in an article.
However, in certain ocean areas, iron is scarce. By introducing iron to these regions, scientists can boost the growth of phytoplankton. As these plants thrive, they take in CO2 through photosynthesis.
Moreover, when they die or are consumed by marine animals, some of the carbon they captured sinks to the ocean floor, potentially keeping it out of the atmosphere for many years.
Controversies and commitment
Although the science behind ocean iron fertilization seems solid, the method has been debated for over a decade. Previous experiments have shown mixed outcomes and, at times, harmful side effects.
These have included the growth of toxic phytoplankton species, creation of oxygen-depleted zones where marine life struggles to survive, and disruptions in nutrients for other marine organisms . Such issues have led to skepticism and reduced activity in this area of research.
However, the researchers at ExOIS believe that the urgent need to address climate change means re-examining all possible solutions, even those with controversial pasts. They aim to tackle these concerns directly, with a commitment to transparency and careful scientific monitoring.
“OIF studies to date were not primarily designed to quantify the durability of carbon (C) storage, nor how wise OIF might be as an mCDR approach,” emphasized the scientists.
Their approach uses advanced computer models to predict the effects of their experiments, and they are open to discussing their work with the public.
Ocean’s potential
A collaborative research effort between British, American, and French scientists, utilizing computer modeling, has suggested that the annual introduction of one to two million metric tons of iron into the ocean could result in the removal of 45 billion metric tons of carbon by the year 2100.
Notably, the Intergovernmental Panel on Climate Change has already highlighted the urgent need to remove large amounts of CO2 from the atmosphere to keep global warming at manageable levels.
The ocean, which can hold vast quantities of carbon, offers a promising avenue for this. ExOIS believes that by enhancing the ocean’s ability to store carbon through iron fertilization, it can significantly contribute to this effort.
“To quantify C sequestration, we introduce a metric called the “centennial tonne,” defined as 1,000 kg of C isolated from atmospheric contact for on average at least 100 years,” highlighted the group.
ExOIS’s ambitious plans
ExOIS is actively seeking funding and working through regulatory processes. They plan to obtain permission for their trials under the London Protocol, an international agreement on ocean fertilization research.
Reportedly, ExOIS hopes to start trials across as much as 10,000 square kilometers of the northeastern Pacific Ocean as soon as 2026.
“We propose a much larger study area of >1,000 to 10,000 km2,” read the research article.
“Based on previous OIF experiments, the ocean systems quickly return to ambient conditions once iron infusions stop—a natural brake on such perturbations—so the field experimentation proposed here, in progressive steps with effective oversight and safeguards, is unlikely to lead to lasting impacts on the ocean systems,” it asserted.
The road ahead
As ExOIS proceeds with this ambitious project, global attention will be on their work. Their efforts might provide new tools in combating climate change.
Nevertheless, the long-term ecological impacts of large-scale iron fertilization are still uncertain. There are concerns about potential harm to deep-sea ecosystems and the risk of triggering unexpected changes in marine environments.
Critics worry that interest in such geoengineering could distract from efforts to reduce CO2 emissions at the source.
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