The main conversation about climate change focuses mainly on one thing: how much carbon is in the air — and, by extension, how to reduce it. However, what is talked about less but could become very important is the amount of carbon in our oceans. There is 50 times more carbon in the ocean than the atmosphere. Some climate researchers believe that if we could slightly increase the amount of carbon the oceans could absorb from the atmosphere, we could avoid some of the worst effects of climate change.
This may sound unusual when you first hear it, but think about it a little longer. The ocean covers roughly 70 percent of the Earth’s surface, and it naturally absorbs carbon dioxide — effectively dissolving it. Phytoplankton in the ocean, use carbon dioxide and sunlight to perform photosynthesis just like terrestrial plants. Oxygen is produced through this process — phytoplankton are actually responsible for about 50 percent of the oxygen in our atmosphere.
Some climate researchers have suggested that if we could increase the amount of phytoplankton in the ocean, we could pull more carbon from the atmosphere. The best-known method for producing phytoplankton blooms is to introduce iron, an important nutrient for the plankton community, into the water. Many parts of the ocean are low in iron, so even a relatively small iron addition could theoretically produce a lot of phytoplankton and thus remove a lot of carbon dioxide from the atmosphere.
“Give me an iron half, and I’ll give you an ice age,” John Martin, an oceanographer at Moss Landing Marine Laboratories, wrote in 1988. At the time, most people were just beginning to recognize the idea of climate change as we now know it. But that’s also at a time when people are beginning to think about how iron enrichment can affect phytoplankton growth, thus altering carbon levels in the atmosphere.
Although climate scientists have spent a significant amount of time discussing this strategy among themselves, there has been no concerted effort to explore it further and take it seriously. Ken Busseler, a marine radiochemist at Woods Hole Oceanographic Institution, a scientist who has done some research into iron enrichment in the ocean. He and his team looked at whether introducing iron could “alter the flow of carbon into the deep ocean” and found that there was a significant effect of carbon sequestration.
His research was conducted nearly 20 years ago, Buessseler told The Daily Beast, and there hasn’t been much since.
“What happened 20 years ago is that we started spinning and spreading a chemical form of iron and looking for phytoplankton — the plant response — and it really showed very clearly that if you improve iron, you can create more uptake from carbon dioxide,” Busseler said. “The difference between now and 20 years ago is that I think the climate crisis is more visible to the public.”
Phytoplankton bloom off the coast of Iceland, as observed from space.
NASA
Using the oceans to combat climate change has become a much-discussed topic among climate scientists in recent years, and Buesseler was part of the group of scientists that released a report through the National Academies of Sciences, Engineering, and Medicine late last year that looked at options, including increasing phytoplankton levels.
“We have a big tank. It already consumes a third of greenhouse gases. The question people are asking the most now is what can we do to enhance this? Buesseler said. “Let’s get out there. Let’s do experiments.”
The experiments themselves won’t cause any harm to the ocean’s natural ecosystem, Buesseler said, but they could tell us a lot about how introducing more iron into the ocean on a much larger scale will affect this ecosystem in the long run. He doesn’t think doing it on a large scale would cause much harm, but it’s important to do the research so we can find out for sure. He said the “very conservative” estimate is that up to gigatons of carbon dioxide could be sequestered each year if the process were carried out on a large scale.
“The difference between now and 20 years ago is that I think the climate crisis is more visible to the public.“
– Ken Busseler, Woods Hole Oceanographic Institution
“It’s going to change the types of plants and animals that grow, but that’s already happening with changes in temperature and acidity,” Busseler said.
Enriching with iron would also be very easy, David Siegel, professor of marine sciences at the University of California, Santa Barbara, told The Daily Beast. You can simply get a 120ft fishing boat and start spreading the iron as it will be most effective for stimulating the growth of phytoplankton.
This can be done relatively inexpensively. Every atom of iron you add in the right places can make tens of thousands of carbon atoms immobile, meaning water absorbs them. “It’s fairly effective,” Siegel said. “You can spread pots that release iron oxide into the water — even just iron ore in the water — and you can make flowers that you can see from space. We know that.”
The effects will happen fairly quickly. Scientists who have introduced iron into seawater in the past have noticed that phytoplankton blooms can begin to appear within the first 24 hours. The ideal place to introduce iron would be places that are less abundant, which would be parts of the ocean — primarily in the Southern Hemisphere — that are nowhere near land. The iron that ends up in the ocean usually comes from dust blowing into the ocean from land.
Both Buesseler and Siegel stressed that this should not be viewed as a substitute for ending the use of fossil fuels. This is still crucial when it comes to having a chance to beat climate change. But avoiding the worst effects of climate change will also require developing decarbonization strategies to reduce the burden of greenhouse gases in the air.
“Even if we remove carbon from our economies, there is still 20 gigatons or so of carbon dioxide that must be removed from the atmosphere to keep us anywhere near the Paris Agreement targets,” Siegel said.