TUMS For The Ocean? Carbon Storage Beneath the Waves

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BY BEN TRACY, SENIOR CLIMATE CORRESPONDENT ON ASSIGNMENT FOR CLIMATE CENTRAL

The Earth’s climate is more out of balance than at any time in observed history, according to a new report from the World Meteorological Organization. Record levels of greenhouse gas concentrations from our continued burning of fossil fuels are rapidly warming the planet and creating increasingly extreme weather.

While the consensus remains that we must drastically cut our planet warming emissions, scientists, including the United Nations Intergovernmental Panel on Climate Change, now say that isn't enough. To avoid the most catastrophic impacts of climate change, we must also pull existing carbon out of the air. While many look to the trees or the sky for solutions, a new wave of researchers is looking at the sea.

"TUMS" for the ocean

In the chilly waters of the Gulf of Maine, scientists have embarked on a first-of-its-kind experiment. Last summer, they released 16,000 gallons of sodium hydroxide into the water to see if they can reduce the ocean's acidity.

"You can kind of think of this like a TUMS for the ocean. It’s an antacid," says Adam Subhas of the Woods Hole Oceanographic Institution.

This process is known as Ocean Alkalinity Enhancement. It is a specific type of Marine Carbon Dioxide Removal, which is a suite of climate engineering technologies designed to strip CO2​ from the atmosphere and store it safely within the deep ocean. Early results of the Woods Hole experiment show it successfully produced conditions for the ocean to take up carbon from the atmosphere and scientists say there was no measurable impact on ocean life from this small-scale test. 

The Cost of Carbon

Our oceans act as a massive planetary sponge, absorbing about a third of carbon pollution generated by our burning of fossil fuels such as oil, gas, and coal. Subhas says the ocean is doing much of the heavy lifting when it comes to climate change. 

"They also take up about 90% of the heat too," Subhas explains. "So they’re doing a huge amount of work in terms of absorbing what we’re putting into the atmosphere."

But that "work" comes at a price. As more CO2 dissolves into seawater, it lowers pH levels, making the ocean more acidic. This shift weakens coral reefs, makes it harder for shellfish to build shells, and ultimately reduces the ocean’s capacity to absorb even more carbon.

Engineering a Solution

On the West Coast, a startup called Ebb Carbon is piloting a similar concept using a different approach. At a facility in Port Angeles, Washington, the company is running seawater through a system that chemically removes acid before returning treated water to the ocean.

"This is where the magic happens," says Ebb’s Kyla Westphal

She points to a complex system of sensors and an outfall pipe where treated, alkaline water flows back into the Pacific.

The company’s vision is to scale this technology by integrating it into existing infrastructure, such as coastal desalination plants. Their first international partnership is slated for Saudi Arabia later this year.

When asked if there really are enough desalination plants in the world to make a dent in the problem, Westphal says "there would be enough capacity to remove around a billion tons of carbon dioxide from the air every year." That would represent roughly 10% of the total carbon removal from the atmosphere scientists say is necessary to avoid the worst climate impacts.

Not a "Free Pass"

Ebb Carbon isn't alone. A Canadian company called Planetary is exploring a similar process at power plants, and some researchers suggest that global shipping fleets could be used to disperse antacid solutions across the open sea.

However, whether this will work at the vast scale of the world’s oceans and how to quantify the impact on global warming remain open questions. The scientific community is also quick to warn that geoengineering the ocean is not a license to continue polluting the atmosphere. 

"No and it can’t be the goal," insists Woods Hole’s Subhas. "If we don’t remain laser focused on actually addressing carbon dioxide emissions then there’s really no reason to be doing this at all."