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The project’s scientists say the experiments would be a significant step toward proving a particularly novel idea to remove climate-warming carbon dioxide from the atmosphere by increasing the pH of the ocean, and thus allowing it to absorb even more carbon dioxide.
Sodium hydroxide, known in commercial products as caustic soda or lye, is a highly toxic chemical that can burn skin at high concentrations and will almost certainly kill or injure any marine life at the water’s surface when the mixture is released, marine biologists who criticized the project said.
The plume south of Martha’s Vineyard would initially span about 56 acres after about one hour, a surface area somewhat larger than that of Boston Common. The Woods Hole scientists acknowledge the impacts to marine life but say the plume would be highly toxic for only a minute or so and they’ll monitor any effects. A marine mammal observer would be on board and the release would only proceed if there are no mammals in the area.
“We don’t want there to be a prospect of a whale or something coming into contact with that,” said Daniel McCorkle, a co-principal investigator for the sodium hydroxide experiment and emeritus scientist in WHOI’s department of geology and geophysics.
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In late May, the Environmental Protection Agency gave tentative approval for both experiments and is expected to make a final determination this summer; if granted, it would mark the agency’s first permit for an “ocean alkalinity enhancement” project.
The experiments are among the many long-shot geoengineering ideas scientists are exploring in earnest as the planet approaches critical warming thresholds that, if exceeded, will likely bring worsened floods, heat waves, biodiversity loss, and more. Geoengineering aims to remove greenhouse gases from the atmosphere by deliberately changing the climate. The ideas range from brightening clouds, to spewing aerosols into the atmosphere to block the sun, to chemically altering the ocean.
“These experiments are absolutely sort of a next step in this scaling up process,” McCorkle said. “But they are still quite small and constrained, compared with any potential future application at scale.”
Oceans currently absorb about one quarter of human-made carbon dioxide emissions from the atmosphere every year. When seawater, which is very basic, interacts with air at the surface, it slowly absorbs carbon dioxide, which makes the water more acidic.
The “LOC-NESS” experiment (an acronym for Locking Away Ocean Carbon in the Northeast Shelf and Slope) would entail releasing a sodium hydroxide solution by boat. That would cause the pH level of the seawater to shoot up to very toxic levels, but the plume would dilute rapidly as it mixes with seawater.
“The immediate change in the chemistry is what drives the carbon dioxide uptake,” McCorkle said.
Related: One scientist's view on using the ocean as a carbon sink
The solution would be released with a red dye to allow scientists to track the plume. Within a few days, the seawater’s pH is expected to return to normal ranges, though more alkaline than usual, and continue taking up carbon dioxide. And the carbon dioxide would transform, locked away by chemical reactions as bicarbonate, which is typically stable for thousands of years.
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Up to 20 tons of carbon dioxide could be sequestered in the first experiment (a tiny amount compared to the tens of billions of tons emitted each year), according to the WHOI’s application.
But environmental groups are concerned the experiment poses far too many unknown threats to the ecosystem.
“We don’t know exactly what the risks are, because no one has been crazy enough to do this before,” said Ben Day, a Massachusetts-based senior campaign manager for Friends of the Earth. “It’s kind of like the thinking that got us here in the first place: Thinking that we can control Earth’s systems without unintended consequences.”
Geoengineering experiments frequently provoke strong opposition from environmental groups that argue tinkering with natural chemical, biological, or atmospheric processes on a global scale ought to be treated as a last resort in tackling climate change.
“The time to do this is, frankly, not when we still actually can solve the climate crisis,” said Brett Hartl, government affairs director for the Center for Biological Diversity. Geoengineering “takes away urgency from dealing with the underlying root causes of the problem.”
Hartl and other advocates are skeptical the experiment will work: It’s unclear if scientists will be able to verify how much carbon dioxide is sequestered in the sea. (It’s exceedingly difficult to measure carbon sequestered in the ocean; project scientists say they’ll be able to measure changes in water chemistry to prove efficacy, at least initially.)
The scientists, along with others working on geoengineering, say that it represents exactly the type of research necessary to understand the risks, and that they’ve learned what they can from the lab.
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“At some point you have to go out and deal with the complexities in the real ocean,” McCorkle said.
Some scientists caution, however, about the dangers to marine life. Even a relatively small amount of sodium hydroxide solution released in the ocean will kill “foundational” marine life, including phytoplankton, zooplankton, and fish larvae, and displace or injure other creatures due to the huge spikes in alkalinity, said James Kerry, an adjunct marine scientist at the James Cook University in Australia.
“I see it, essentially, as trying to address one form of marine pollution — carbon dioxide — with another” pollutant, said Kerry, who is also a senior marine and climate scientist for OceanCare, a marine conservation nonprofit organization based in Switzerland.
In a statement, EPA spokesperson Angela Hackel wrote the agency is consulting with the National Marine Fisheries Service and US Fish and Wildlife about potential impacts to fish habitats and endangered species as part of the permitting process.
Geoengineering research has attracted enthusiastic venture financing in recent years, yet it is often criticized by opposing groups as overly hyped. But the Cape scientists leading the project point out the experiment is not being pursued by a startup company with profit in mind, but by a research institution with a legitimate scientific question: Could this work?
Even if it does, both geoengineering researchers and critics agree that carbon dioxide removal technologies are alone not enough to combat climate change. While it may help on the margins, most agree it cannot be a replacement for the massive cuts needed to reduce greenhouse gas pollution.
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“We should not be doing [geoengineering] at a large scale now, instead of trying to change our energy system,” said Andrew Dickson, a marine chemist at the University of San Diego who has researched the subject. “But ... you’ve got to do a lot of this background science now to even have a chance of being there when you would say that it would be a good time to start.”
Erin Douglas can be reached at erin.douglas@globe.com. Follow her @erinmdouglas23.
