Feature Story | February 11, 2022
By Megan Lowry
Imagine an ocean enabled to help solve one of society’s biggest threats: carbon dioxide. In one proposed scenario, a system of pipes and pumps would move water from the surface to the deep ocean. In another, massive seaweed farms would dot the coastlines. And in yet another, nutrients sprinkled on the ocean surface would encourage the growth of photosynthesizing plankton. Each of these are part of a set of proposed — albeit still largely theoretical — strategies to remove CO2 from the atmosphere using the ocean.
Covering 70 percent of the world’s surface, the ocean is what researchers call a natural carbon sink. Through photosynthesis, currents, and other natural processes, the ocean and its plants and marine life pull CO2 from the air, which is then eventually stored in the deepest parts of the sea. As the world seeks to meet net-zero emissions goals and avoid the worst impacts of climate change, some have proposed interventions like those described above to capture CO2.
A National Academies of Sciences, Engineering, and Medicine report released late last year calls for a $125 million research program to explore six different nascent ocean-based CO2 removal strategies — and to help society gain a greater understanding of their risks, benefits, and potential impacts.
But these proposals to change ocean processes are not without controversy and debate. A recent National Academies webinar explored the most pressing social questions around ocean CO2 removal.
“Messing about with the oceans” is something that always raises a strong public response, said Nick Pidgeon, professor of environmental psychology and risk and director of the Understanding Risk Research Group at Cardiff University. “They just don’t like the feel of this. It just doesn’t seem right.”
“People value the ocean. It’s often seen as a wild space,” added Holly Buck, assistant professor of environment and sustainability at the University at Buffalo and member of the committee that wrote the 2021 National Academies report. “People are concerned about it being industrialized or tampered with.”
Some of the potential risks of ocean-based CO2 removal identified in the National Academies report include unintended environmental effects — for example, mass seaweed farming could trigger unpredictable and unwanted changes to local ecosystems, and artificial upwelling and downwelling of water could change ocean surface temperatures. There’s also risk in these strategies failing to work after investing time and resources, risk in scaling them to the level needed to significantly impact atmospheric CO2, and the risk that any efficacy they could have won’t last.
One particular point of contention is the worry that developing the ability to remove carbon from the atmosphere on a mass scale might slow progress in reducing carbon emissions in the first place. “There’s opposition to carbon removal generally … because people are concerned that it might delay or deter mitigation,” said Pidgeon.
Ocean-based CO2 removal approaches explored in the National Academies’ report
“It’s absolutely clear that in order to meet our targets, we are likely to need some form of carbon removal.”
But even with significant reductions to carbon emissions, “it’s absolutely clear that in order to meet our targets, we are likely to need some form of carbon removal,” said Pidgeon.
“There may be a point in time where the harm from climate change may outweigh those risks [of ocean-based carbon removal],” added Buck. “It’s very hard to say anything about that, given our low level of information.”
Research recommended by the National Academies report could shed more light on these risks and trade-offs, and enable more informed decision-making in climate policy. Buck emphasized that now is the time for researchers to be creating this knowledge: “We should be finding this out sooner rather than later.”
Buck said that it’s important for the public to be involved in any research that moves forward. Pidgeon agreed. “You have to engage them very early,” he said. “That’s one of the lessons that have been learned from other technologies … that have encountered extreme opposition. If you don’t bring people in early, they’re likely to find out at the wrong time and get very frustrated.”
To incorporate community views and ethical considerations into their work, Pidgeon said researchers can look to parallel scientific issues in which there is public contention and debate, such as nuclear waste disposal or human health.
“A good example might be human embryo technology,” said Pidgeon. “In the U.K., we have a panel of ethicists and lay citizens and others who are given these particular conundrums to wrestle with, when the scientists come up with research proposals in potentially controversial areas.” He added, “We need to learn from some of those other experiences if we are to take forward this technology.”
Keeping the public involved in research also means “you may identify ways in which the science has to change.”
Bringing non-scientists into the research can also help illuminate which aspects of ocean-based carbon removal are truly relevant and most important to a community. “As scientists, we tend to think about an issue in a certain way,” said Pidgeon. “And that may not relate to what really matters to someone in a coastal community.” Keeping the public involved in research also means “you may identify ways in which the science has to change.”
Given the urgent and immediate impacts of climate change being felt around the world, one attendee asked if scientists truly have time for careful research that includes the public. Buck replied, “We do, and there’s huge risks to not doing it, because we want to set up a system that’s going to work.”
“You need a yes on all of those levels,” said Pidgeon. “You need your ethics board to say yes. You need the general conversation at the citizen level to say yes. And you need the local community’s consent as well.”