A team of researchers are calling for a new generation of carefully designed ocean iron fertilization (OIF) field trials to determine whether this marine carbon dioxide (CO2) removal method can safely and effectively leverage a natural ocean process to pull CO2 out of the atmosphere. Led by the Woods Hole Oceanographic Institution, the authors, including two from the University of Hawaiʻi at Mānoa, argue that larger, longer studies with rigorous monitoring and clear "go/no-go" safeguards, are needed to accurately assess OIF as a potential long-term CO2 storage solution. The paper was published in Dialogues on Climate Change .
"The ocean science community must explore all possible means for reducing atmospheric carbon dioxide levels, and identify any unintended ecological consequences," said David Karl, co-author, professor of oceanography and director of the Center for Microbial Oceanography: Research and Education in the UH Mānoa School of Ocean and Earth Science and Technology (SOEST). "Humans continue to pollute our planet; the time for bold action is now."
Past OIF field studies found that relatively tiny additions of iron in some parts of the ocean can stimulate the growth of small, plant-like organisms known as phytoplankton that live in the surface ocean. These organisms use sunlight and CO2 dissolved in seawater to grow and multiply, which in turn pulls more CO2 out of the atmosphere into the surface ocean in the process. However, those early experiments were not designed to assess the efficacy, durability and feasibility of OIF, nor did they specifically evaluate the broader ecological and biogeochemical impacts of large-scale additions of iron.
The next generation of trials would need to capture phytoplankton bloom development, and the process of bloom decay, the fate of newly produced carbon, and any potential ecosystem impacts. The authors propose experiments lasting more than 3–6 months and spanning an area of about 1,000 square kilometers, with an explicit requirement to document a return to natural conditions after iron additions end.
The authors suggested the Gulf of Alaska in the Northeast Pacific as a promising location based on the region's low-iron conditions, the availability of decades of research in the area at Ocean Station Papa, evidence of natural iron-driven blooms in the past, and physical characteristics that may help keep the iron-fertilized patch from dispersing too rapidly.
