Science

Artificially inducing phytoplankton blooms could lower carbon dioxide levels and combat climate change

Artificially inducing phytoplankton blooms could lower carbon dioxide levels and combat climate change
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The main talk of climate change is mostly focused on one thing: how much carbon is in the air — and more broadly, how to reduce it. However, what is less talked about, but could become incredibly important, is how much carbon is in our oceans. There is 50 times more carbon in the ocean than in the atmosphere. Some climate scientists believe that if we could only slightly increase the amount of carbon the oceans can absorb from the atmosphere, we could avoid some of the worst effects of climate change.

This may seem unusual at first, but think about it a little longer. The ocean covers about 70 percent the Earth’s surface, and it naturally absorbs – and effectively dissipates – carbon dioxide. phytoplankton in the ocean, they use carbon dioxide and sunlight to carry out photosynthesis, just like plants on land. This process produces oxygen – phytoplankton is actually responsible for about 50 percent of oxygen in our atmosphere.

Some climate scientists have suggested that if we could only increase the amount of phytoplankton in the ocean, we could remove more carbon from the atmosphere. A well-known method of creating a phytoplankton bloom is to insert iron, an important nutrient for the plankton community, into the water. Many parts of the ocean are little ironso even a relatively small addition of iron could theoretically produce a lot of phytoplankton and thereby remove a lot of carbon dioxide from the atmosphere.

“Give me half a tanker of iron and I’ll give you an ice age,” said John Martin, an oceanographer at Moss Landing Marine Laboratories. wrote in 1988. Back then, most people were just beginning to get comfortable with the idea of ​​climate change as we know it today. But that was also around the time people started thinking about how iron fertilization might affect the growth of phytoplankton and thereby change the carbon content of the atmosphere.

Although climate scientists have spent much time discussing this strategy among themselves, there has been no concerted effort to investigate it further and take it seriously. Ken Buesseler, a marine radiochemist at the Woods Hole Oceanographic Institution, is one scientist who has done this some research into the iron fertilization in the ocean. He and his team investigated whether introducing iron could “change the flow of carbon into the deep sea” and found that there was a significant carbon sequestration effect.

Buesseler told The Daily Beast that his research was done almost 20 years ago and not much has happened since.

“What happened 20 years ago is that we started taking a chemical form of iron and looking for this phytoplankton – the plant response – and actually it really showed very clearly that by increasing iron levels you get better absorption of carbon dioxide,” Buesseler said. “The difference between now and 20 years ago is that I think the climate crisis is so much more obvious to the public.”

A phytoplankton bloom off the coast of Iceland observed from space.

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Using the oceans to combat climate change has become a hotly debated topic among climate scientists in recent years, and Buesseler was part of a group of scientists who published a report Late last year by the National Academies of Sciences, Engineering, and Medicine, which looked at the options available, including increasing phytoplankton levels.

“We have a large reservoir. It already absorbs a third of the greenhouse gases. The question people are asking more often now is: What can we do to improve this?” said Büsseler. “Let’s get out of there. Let’s do experiments.”

The experiments themselves wouldn’t harm the ocean’s natural ecosystem, Buesseler said, but they could tell us a lot about how dumping more iron into the ocean on a much larger scale might affect that ecosystem in the long term. He doesn’t think this would do much harm on a large scale, but it’s important that the research is done so we can know for sure. He said a “very conservative” estimate would be that up to a gigatonne of carbon dioxide could be sequestered each year if this process were scaled up.

The difference between now and 20 years ago is that I think the climate crisis is much more obvious to the public.

Ken Buesseler, Woods Hole Oceanographic Institution

“It will change the types of plants and animals that grow, but that’s already happening with the changes in temperature and acidity,” Buesseler said.

David Siegel, a professor of marine sciences at the University of California, Santa Barbara, told The Daily Beast that iron fertilization would also be fairly easy to do. You could just get a 120 foot fishing boat and start putting the iron where it is most effective to stimulate phytoplankton growth.

“It can be done relatively cheaply. Each iron atom you add in the right places can result in tens of thousands of carbon atoms being fixed, meaning they are absorbed by the water. “It’s pretty efficient,” Siegel said. “You can use vessels that release iron oxide into the water – even just iron ore into the water – and you can create blooms that you can see from space. We know that.”

The effects would kick in fairly quickly. Scientists who have historically incorporated iron into seawater have found that phytoplankton blooms can become visible within the first 24 hours. The ideal place to introduce the iron would be where it is least available, i.e. parts of the ocean – mainly in the southern hemisphere – that are not close to land. Iron that ends up in the ocean usually occurs from dust blowing from land to sea.

Both Buesseler and Siegel stressed that this should not be seen as an alternative to ending the use of fossil fuels. This is still crucial when it comes to beating climate change. But to avoid the worst impacts of climate change, carbon removal strategies must also be developed to reduce airborne greenhouse gas loads.

“Even if we decarbonize our economies, we still need to remove about 20 gigatons of carbon dioxide from the atmosphere to keep us close to the Paris Agreement goals,” Siegel said.

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