Scientists are conducting experiments on the ocean by increasing its iron content to encourage the growth of organisms that absorb carbon dioxide. While the studies are initially promising, some researchers argue that ocean iron fertilization will have little effect on reversing climate change.
Ocean iron fertilization context
The world’s oceans are partially responsible for maintaining atmospheric carbon levels, primarily through phytoplankton activity. These organisms take atmospheric carbon dioxide from plants and photosynthesis; those that aren’t eaten, preserve carbon and sink to the ocean floor. Phytoplankton can lie on the ocean floor for hundreds or thousands of years. However, phytoplankton needs iron, phosphate, and nitrate to grow. Iron is the second most common mineral on Earth, and it enters the ocean from dust on the continents. Similarly, iron sinks to the seafloor, so some parts of the ocean have less of this mineral than others. For example, the Southern Ocean has a lower iron level and phytoplankton population than other oceans, even though it is rich in other macronutrients.
Some scientists believe that encouraging the availability of iron underwater can lead to more marine micro-organisms that can absorb carbon dioxide. Studies in ocean iron fertilization have been around since the 1980s when marine biogeochemist John Martin conducted bottle-based studies demonstrating that adding iron to high-nutrient oceans rapidly increased phytoplankton populations. Of the 13 large-scale iron fertilization experiments conducted due to Martin’s hypothesis, only two resulted in removing carbon lost to deep sea algae growth. The remaining failed to show an impact or had vague results.
According to the Smithsonian Magazine, in the 2000s, decades after Martin’s radical concept, researchers are debating how much of an impact iron dust had on the Ice Age and whether geoengineering oceans could be a viable solution. For example, although iron fertilization in the Southern Ocean increased during the Ice Age, scientists argue that it reduced carbon dioxide levels in the atmosphere.
Pulling carbon from the atmosphere by encouraging the growth of marine micro-organisms, although a promising concept, a study released in 2020 by the Massachusetts Institute of Technology (MIT) argued that ocean iron fertilization was unlikely to slow down climate change. Lead author of the report and oceanographer Jonathan Lauderdale said in a press release that iron fertilization could not significantly affect carbon levels in the ocean because there are already enough marine carbon-eating microbes in the first place. Additionally, researchers found that the relationship between microbes and minerals is not one-sided by simulating mineral concentrations and circulation patterns in different parts of the ocean. According to Lauderdale, the microbes have the self-regulating capacity to alter ocean chemistry to suit their needs better.
Implications of ocean iron fertilization
Wider implications of ocean iron fertilization may include:
- Scientists continuing to conduct iron fertilization experiments to test if it can revitalize fisheries or work on other endangered marine micro-organisms.
- Some companies and research organizations continuing to collaborate on experiments that attempt to carry out ocean iron fertilization schemes to collect carbon credits.
- Raising public awareness and concern of the environmental hazards of ocean iron fertilization experiments (e.g., algae blooms).
- Pressure from marine conservationists to permanently ban all large-scale iron fertilization projects.
- The United Nations creating stricter guidelines on what experiments will be allowed on the ocean and their duration.
Questions to comment on
- What other repercussions might result from conducting iron fertilization in various oceans?
- How else might iron fertilization affect marine life?