Will stashing more CO2 in the ocean help slow climate change?

For decades, ocean waters have helped hold back the juggernaut of global warming, absorbing at least a third of the carbon dioxide emitted by human activities since the Industrial Revolution began.

Technologies that remove carbon from the atmosphere could help turn the thermostat back down by the end of the century. “The latest IPCC report notes that to meet the climate goals, we have to employ carbon dioxide removal technologies,” says geochemist Gabriella Kitch of the U.S. National Oceanic and Atmospheric Administration in Silver Spring, Md.To stay on track with Paris Agreement goals, the world needs to ramp it up, removing 10 billion to 15 billion tons of COannually by 2050, Kitch says.

But the biggest challenge of all is time. Researchers are racing to explore these uncharted waters before the climate crisis worsens. The ocean’s carbon storage capacity is vast. For example, from 10,000 years ago until the dawn of the Industrial Revolution, the atmospheric COconcentration was about 280 parts per million. But at the height of the last ice age, about 20,000 years ago, that concentration was just 180 ppm. The “missing” 100 ppm of COduring the ice age was all stored in the ocean, in part due to decreased ocean circulation at this time.

In seaweed farming, photosynthetic seaweed would absorb carbon dioxide and then be sunk to the deep sea to sequester the carbon.. Cultivating seaweed could increase that to about 1 billion tons annually, according to a 2022 report by the National Academies of Sciences, Engineering and Medicine.Macroalgae alone probably wouldn’t make a huge dent in the amount of carbon the world needs to sequester and wouldn’t store it for very long.

But things are very different now as a result of the climate crisis, he says. “There’s absolutely a big change, working in this area, from 15 to 20 years ago.” In 2022, he and colleagues formed the Exploring Ocean Iron Solutions consortium, identifying key research questions for the field and proposing best practices for studying them. This time, societal acceptance and citizen participation are highlighted as core features of any ocean fertilization project.

Artificial upwelling would bring nutrients to the surface to stimulate algal blooms while downwelling would send carbon-laden water to the deep sea for sequestration.Artificially re-creating this upwelling effect by pumping nutrient-rich waters from the deep ocean toward the surface could be another way, theoretically, to give phytoplankton a boost. Similarly, carbon-laden surface waters might be sent downward to be sequestered.

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Fossil fuel giants and Big Tech back audacious project to pull CO2 from Pacific OceanAn audacious new effort to pull carbon dioxide out of the Pacific Ocean as a way to fight climate change is being backed by fossil fuel giants and Big Tech. The technology, called “direct ocean capture” (DOC), is still in its early stages and needs further testing. Caltech researchers founded the startup Captura, which has received funding from the US’s biggest gas utility. Captura is setting up its largest pilot project at the Port of Los Angeles.
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