The report reads like the basis for a science fiction novel.
In one scenario, humanity fights climate change by fertilizing the ocean, boosting the growth of tiny photosynthetic creatures that pull carbon out of the atmosphere. In another, scientists change the chemistry of seawater so it can absorb more planet-warming gases. There is even a proposal for sending electrical currents through the waves, breaking apart molecules and enhancing their ability to take up carbon dioxide.
It’s not yet clear whether these tactics would meaningfully slow the warming of the planet, a panel of experts writes in a new study from the National Academies of Sciences, Engineering and Medicine. Many of their potential side effects are still unknown.
But the 300-page report from one of the country’s top research organizations argues that the United States should at least investigate whether ocean-based carbon-removal strategies are worthwhile.
After all, said University of Virginia marine scientist Scott Doney, who led the report, the toll of climate change is already staggering. Greenhouse gas emissions are continuing to rise. There may come a time when averting catastrophic warming depends on sucking up carbon dioxide that has already been unleashed. In that case, Doney said, “the goal is to have a research strategy that could inform societal decisions.”
The idea of hacking the planet to counteract climate change — a practice called “geoengineering” — is controversial in environmental circles. Many activists worry that the distant promise of unproven technological fixes distracts people from the emissions cuts that need to happen today.
Others point out that large-scale interventions in the ocean, land or atmosphere could have devastating unintended consequences: altering weather patterns or ocean currents, disrupting farms and fisheries, contaminating systems people and animals depend on to survive. The Earth is vast, complex and ancient, critics argue; it is the height of hubris for humans to think we can safely interfere with a system that’s been evolving for more than 4 billion years.
But a previous study from the National Academies found that humanity is unlikely to meet its most ambitious climate goal of limiting warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) without some form of carbon-dioxide removal (CDR). By the middle of the century, that study said, people should be taking at least 10 gigatons of carbon out of the atmosphere every year — equal to roughly a quarter of current annual global emissions.
The new report — released Wednesday and sponsored by ClimateWorks, a San Francisco-based nonprofit — is adamant that carbon-dioxide removal is not a substitute for immediately eliminating fossil fuel use and curbing greenhouse gas pollution. It does not endorse any of the six strategies it considers or even advocate for CDR to be deployed.
Instead, it outlines a 10-year, $1.1 billion research program that would fill in crucial knowledge gaps about each technology.
Some of the questions are purely scientific, Doney said: “Does it actually work? Does it store carbon for sufficiently long periods of time? What are the environmental impacts?”
Many more questions are legal, economic or ethical: “How would you govern this? What are the dimensions of social acceptability?” Doney said. “If you could slow climate change or stabilize climate at a lower warming level, is that worth the trade-offs of these deliberate changes to the ocean? … These are things society needs to decide.”
The report also recommends the development of a research code of conduct for ocean-based CDR, with stipulations that the experiments be tightly regulated and involve experts from Indigenous groups and other vulnerable communities. The scientists say the $125 million foundational research agenda must include surveys, legal analyses and in-depth interviews with the people whose lives and livelihoods will be affected by the projects.
Experiments should be “co-produced with communities,” said Holly Buck, a sociologist at the University at Buffalo and a contributor to the report. Including locals in the design and deployment of projects will make them more equitable and could reveal insights scientists had never considered.
And researchers must be willing to change course, Doney said, if their work turns out to be ineffective or dangerous, or if more powerful methods come to light.
“This is the kind of deep dive we need,” said Kim Cobb, a climate scientist and oceanographer at the Georgia Institute of Technology who was not involved in the National Academies study. “It helps us to understand the potential benefits and downside risks and all the warts that you don’t get in the battles that are waged on op-ed pages.”
Cobb knows those battles well. This October she co-wrote a piece for the Hill arguing that geoengineering amounts to “playing dice with the planet.”
In an interview, she noted that fossil fuel companies often tout their investments in carbon-dioxide removal as evidence of their commitment to climate action, even as they earn far more from the extraction and use of planet-warming fossil fuels.
Yet Cobb applauded the research strategy laid out in the National Academies report. “If we’re going to blunt that very large and well-funded publicity campaign … we have to take those black-box talking points out of the board rooms of big fossil fuel companies and into the public awareness in a way that is auditable and accountable and transparent,” she said.
And not all of the carbon-dioxide removal strategies examined by the National Academies are high-tech geoengineering tactics.
The ocean already absorbs about a quarter of all carbon dioxide emitted by human activities, the report notes. Restoring crucial ecosystems to their preindustrial glory could boost their CO2-uptake and deliver a host of other benefits: providing habitat for endangered species, for instance, and protecting fisheries people depend on for food.
One study estimates that protecting just eight whale species could save as much as 8.7 megatons of carbon — equal to about 6,000 wind turbines running for a year. That’s because whales’ massive frames contain huge amounts of organic material, which all sinks to the seafloor when the animal dies.
But it’s not yet known how much carbon ecosystem restoration would actually remove from the atmosphere or which projects are the most cost-effective. At the same time, communities will have to weigh the value of habitat protection against other potential ocean activities — such as fishing for food or generating clean electricity from offshore wind farms.
One of the most well-known and divisive ocean-based CDR strategies is known as “ocean fertilization.” The technique involves sprinkling the sea surface with nutrients, such as iron or phosphorous, that could bolster the growth of carbon-munching photosynthetic plankton. Theoretically, these plankton would be eaten up by other animals, and the carbon within them would eventually end up on the seafloor when the animals defecate or die.
But researchers haven’t firmly established that ocean fertilization really does result in lasting carbon removal. And it may lead to toxic algae blooms that deplete the sea surface of oxygen. A history of rogue experiments with uncertain outcomes has also given the practice a bad reputation; since 2008, the United Nations Convention on Biological Diversity has barred ocean fertilization projects in international waters.
Other proposed tactics for storing carbon in the ocean have never been tested on a large scale in the real world. Among them are the idea of artificial upwelling — pumping cold, nutrient-rich water from the deep ocean to the sea surface to feed phytoplankton — and electrical interventions to change the ocean’s chemistry.
The ramifications of such projects could be profound, Cobb acknowledged. That scientists are considering them is a testament to how much more brutal climate change may soon become.
“We’ve already been using the ocean as a dumping ground of CO2 and heat,” Cobb said. “If we can intervene with science-based approaches that recognize the co-benefits and have a clear eyed view of the risks, then yes, I think we should be considering those. That’s my stance on the dismal state of where we are.”