The gigantic plan to ‘fertilize’ the Pacific and change the climate is no longer ‘crazy’

The amount of carbon dioxide (CO₂) present in the atmosphere has determined the temperature of the planet for millions of years and emissions of human origin are causing accelerated global warming. Therefore, the solution is almost obvious: we must reduce this gas to return to a normal situation. The question is how to do it. Stopping emissions is a very ambitious goal and, even if it is achieved, the climate will take decades to recover. Therefore, Some scientists are thinking of compelling alternatives and on a large scale.

One of them is based on the fact that the oceans act as large carbon sinksWhat does that mean? It’s something we’ve known for a long time: a study published in Science 20 years ago I calculated that the world’s seas are capable of swallowing almost one third of emissions from human sourcesThe main culprits of this are phytoplankton, the group of tiny plant organisms that live floating in the water. Just like trees, they use CO2 and sunlight to produce energy and grow. These tiny life forms absorb carbon and, when they die, sink to the depths.

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From there, an old idea speculates on the possibility of increase the amount of phytoplankton from the oceans to remove CO₂ more quickly. To achieve this, the waters would simply need to be fertilised with iron, an essential nutrient for phytoplankton. However, this proposal has never been put into practice. For various reasons, this and other geoengineering projects to combat climate change – techniques that are supposed to help slow down global warming on a large scale – have met with scepticism from the scientific community. However, some experts are ready to take it seriously once and for all.

Exploring Ocean Iron Solutions (ExOIS) it’s a international scientific research consortium The project is made up of institutions from various countries, mainly the US and several Asian countries, which plans to carry out a gigantic real test to check whether the idea is viable. The project, detailed by its promoters a few days ago in the scientific journal Frontiers in Climateshould start in 2026 and involves fertilizing with iron an area located in the northeast of the Pacific Ocean that would cover about 10,000 square kilometersan area equivalent to the average size of a Spanish province (approximately the surface area of ​​Huelva, Soria, Navarra or Zamora).

Phytoplankton seen under a microscope.

A very controversial route

The goal is to analyze the capacity to eliminate CO₂ in this way and see what effects it can have on marine ecosystems. At the moment, researchers are working with computer models and trying to raise public and private funds to achieve the goals. 160 million dollars they need for the gigantic trial. In addition, they must obtain the necessary permits: although the London Protocol prohibits actions that may contaminate or alter the marine environment; exceptions may be made for scientific research.

However, there is a precedent that sparked a great international controversy more than a decade ago, when the Canadian businessman Russ George dumped more than 100 tons of iron sulphate particles near the west coast of its country, with the aim of indirectly boosting (also, thanks to the increase in plankton) salmon fishing. At that time, some companies intended to use this route to be able to sell carbon credits (the mechanism by which emissions are offset through other projects), but the controversy ended in the prohibition of these practices when they were for commercial purposes. Now, scientists working in this field hope to give it a new approach.

Presentation of the initiative at a scientific forum. (ExOIS)

“It’s a small change in biology, compared to doing nothing and watch this planet crumble,” has explained Ken Buesseler, a researcher at the Woods Hole Oceanographic Institution (USA), one of the leaders of the initiative. The project aims to add nutrients to the waters and monitor what happens with all kinds of media, From satellite images to floating sensors or underwater drones. Scientists hope to overcome reluctance through public participation and transparency.

In general, all geoengineering projects have raised suspicions in recent years, as they seem to promise almost magical solutions without going to the root of the problem, the emission of greenhouse gases. The most famous and spectacular modality is solar geoengineering, which proposes, for example, injecting aerosols in the stratosphere to have a reflective effect and thus cool the atmosphere. The most sceptical scientists warn of the possible side effects that large-scale actions would have, since they could potentially alter the climate of some countries, with unforeseeable consequences.

Acting on the stratosphere, another geoengineering option against climate change.

The plan B we need?

From this point of view, boosting phytoplankton seems to be a somewhat more harmless way, but is it necessary? For many experts, this type of initiative represents a kind of plan B to save the planet. “A growing number of researchers are studying other courses of action to avoid the most pernicious effects of global warming,” Mariano Marzo Carpio, emeritus professor at the University of Barcelona and director of the Energy Transition Chair at the Repsol Foundation-University of Barcelona, ​​told El Confidencial. In his opinion, the rise of these studies is justified “in case the increasingly likely case were to arise that current mitigation and adaptation efforts were insufficient.”

In fact, in the United States, the National Academies of Science, Engineering, and Medicine published a report in 2021 urging not only to strengthen climate change mitigation and adaptation policies, but also to develop research on large-scale climate interventions in a coordinated manner with other countries, as the ExOIS project does. Decarbonizing the economy “it is not working as we expected”acknowledges the expert from the University of Barcelona, ​​so “it would be convenient if, from the middle of this century, we were in a position to apply geoengineering techniques.”

Air polluted by greenhouse gases. (EFE)

In any case, supporters and detractors of these grand plans agree on one thing: geoengineering should not replace current policies that seek to reduce emissions. That is, if any of the proposals were to prove effective, it should not become a carte blanche to continue emitting CO2 at an unbridled rate. “Rather, it is a tool that, backed by a great research effortcould become an option to cool the atmosphere,” says Marzo Carpio, “in the event that current efforts prove insufficient.”

Why is it so complicated?

However, the project to stimulate the growth of marine phytoplankton is not as simple as it seems, because the relationships between global warming and these tiny plants are really convoluted. For example, according to some studiesclimate change itself is causing its decline. The increase in water temperature is modifying ocean circulation, so that nutrients are less available to these microorganismswhich could decrease globally by 6% in the coming decades.

The ocean, from a boat. (EFE)

According to research by Canadian scientists published in the magazine Naturethis has already been happening for more than a century. On average, in all oceans, the decline in phytoplankton could be 1% each year and In the northern hemisphere it would have already dropped by 40% since 1950. These data raise many questions. On the one hand, they indicate that the effort to fertilise the seas so that they capture more CO2 should be much greater than expected. On the other hand, they increase doubts about the final result: would it represent a turning point in lowering the planet’s temperature or would we only be compensating for part of the loss?

And study published in Nature Geoscience The study, which involved the Autonomous University of Barcelona, ​​had already warned years ago that iron fertilisation of marine ecosystems could be less effective than initial calculations indicated. The research, in which the Autonomous University of Barcelona participated, focused on the South Pacific, and detected that the presence of iron also favoured the growth of small organisms with calcareous shells that feed on phytoplankton and, unlike phytoplankton, produce CO2. In the end, the balance was still positive, but the calculations on the effect of fertilisation would have to be corrected and reduced by at least 30%.

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On the other hand, experts are concerned about the collateral damage that could be caused by an excessive increase in phytoplankton. For example, increased oxygen consumption in the water could affect other forms of marine lifeincluding fish. Similarly, these microorganisms, in addition to iron, would also need nutrients such as phosphorus and nitrogen, taking them away from the rest of the ocean ecosystem.

To make matters worse, trying to get the oceans to store larger amounts of CO2 has a perverse effect, they say. some scientific worksCarbon dioxide makes the waters more acidic (they have a lower pH) and this, combined with higher temperatures, would harm a very abundant type of calcified phytoplankton (coccolithophores), which traps CO2 and sinks it to the bottom of the ocean. What is the final balance of all these imbalances? Is a major geoengineering project to try to turn the climate around really worth it? Only a large-scale test will likely provide the answers.