Marine ecosystems, essential for life on Earth, are under threat from a new set of high-risk technological interventions known as marine geoengineering, according to experts. These technologies, which include efforts to manipulate ocean conditions to combat climate change, could exacerbate existing environmental issues and harm the planet’s life-support systems.
The ocean plays a crucial role in sustaining life, producing around 50% of the oxygen we breathe and absorbing 30% of greenhouse gas emissions and nearly all the excess heat generated by human activities. However, climate change, pollution, habitat destruction, acidification, and overfishing have already placed immense pressure on these fragile ecosystems.
Now, marine geoengineering—techniques such as seeding the ocean with iron to stimulate carbon-absorbing phytoplankton growth and increasing cloud reflectivity by spraying saltwater mist—poses a new threat. While proponents argue these methods could help combat climate change, critics highlight that they do not address the root cause: the continued use of fossil fuels.
Experts argue that these technologies are either unworkable, unscalable or too dangerous to be deployed. For example, ocean liming, which involves adding alkaline substances to the ocean to enhance its carbon dioxide absorption, would require an enormous amount of resources. One analysis suggests it would necessitate the use of nearly all the world’s active large ships, powered by fossil fuels, thereby negating the effort’s potential benefits. Additionally, the mining and processing required to obtain the necessary alkaline substances would significantly increase pollution.
The potential ecological impacts of such interventions are also a major concern. Rapid changes in the ocean’s chemical composition could harm marine species adapted to stable environments, while the introduction of mineral particles could contaminate water, block sunlight, and disrupt the biological carbon pump critical for storing CO2 in the deep ocean.
Another controversial geoengineering technique, marine cloud brightening, involves pumping seawater into the atmosphere to increase cloud reflectivity. While this could potentially reduce temperatures, it might also shift rainfall and monsoon patterns, exacerbating droughts and hurricanes. The sudden termination of such a project could lead to rapid temperature increases with catastrophic consequences.
In light of these risks, the decision by Alameda, California, to refuse a marine-cloud-brightening experiment has been praised as a positive step. This move reflects growing public and governmental awareness of the dangers these technologies pose, even at the experimental stage.
Despite a de facto moratorium on marine geoengineering under the UN Convention on Biological Diversity since 2010, international efforts to regulate these technologies have been slow. Experts are calling for more effective global regulation, particularly as companies in this emerging field begin to sell carbon credits, potentially prioritizing profit over environmental protection.
As the oceans face increasing strain, experts argue that the focus should remain on reducing fossil fuel use rather than relying on unproven and potentially harmful geoengineering technologies. Protecting marine ecosystems is essential to sustaining life on Earth, and the risks associated with marine geoengineering are too great to ignore.