WOODS HOLE — With the federal government following a blueprint to deter climate research at agencies like the National Oceanographic and Atmospheric Administration (NOAA), scientists at the Woods Hole Oceanographic Institution, a private marine research nonprofit, are hoping to forge ahead with an experiment to explore how ocean waters might be used to absorb excess carbon dioxide from the atmosphere.

WHOI is awaiting approval from the Environmental Protection Agency on a permit to continue work initially scheduled for last summer off Martha’s Vineyard. It involves releasing 16,500 gallons of sodium hydroxide into the ocean to gauge its ability to improve the ocean’s ability to absorb carbon dioxide.

The experiment is now set to take place in an area called Wilkinson Basin, about 38 miles northeast of Provincetown. The period for public comments on the permit closes on Feb. 14.

The technique, known as ocean alkalinity enhancement, or OAE, has been the subject of laboratory experiments for decades, but this field test will be the first of its kind in U.S. waters. It aims to validate WHOI’s experiments that suggest OAE can effectively absorb carbon without harming the local environment.

A similar test that was set to take place off Martha’s Vineyard last fall was postponed when permitting was slowed by questions and additional monitoring requirements from the National Marine Fisheries Service and the U.S. Fish and Wildlife Service, according to an August report in the Boston Globe. By the time the WHOI researchers got the green light, the U.S. Academic Research Fleet vessel needed for the experiment was not available, according to WHOI associate scientist Adam Subhas, the principal investigator of the project.

Plans then got underway to conduct the test in the summer of 2025 — with changes based on EPA comments and sessions open to the public, including one held at the Eastham Public Library, according to Subhas. For one, this release of sodium hydroxide in the Wilkinson Basin was going to be 66,000 gallons, he said, but further laboratory experiments gave the team the data they needed to scale the release down by 75 percent.

“We don’t want to do more than is necessary,” Subhas said. “If we can answer the science questions through a tighter, more controlled experiment, we should absolutely do that.”

 

Undoing Acidification

According to the NOAA, if humans were to stop emitting CO₂ today, the planet would continue heating for several decades. This has led to calls for emissions reductions to be paired with carbon removal to avert the worst damage of climate change.

Already, nearly one third of all CO₂ emitted by human activity is absorbed by the ocean, according to NOAA’s Ocean Facts website, making it an extremely important natural “carbon sink.” When this CO₂ is absorbed, however, it becomes carbonic acid.

All this carbon dioxide entering the ocean has made its waters more acidic than they were 250 years ago, according to an analysis by the European Environment Agency. Local fishermen on Cape Cod know the effects of this increased acidity — it dissolves animal shells, destroys coral reefs, and leads to processes that cause hypoxia, pushing fish and lobsters out of habitats they once occupied.

Introducing alkaline materials into the ocean effectively cancels out some of the acidity of the CO₂. In doing so, it also raises the ocean surface’s buffering capacity, allowing it to absorb even more carbon from the atmosphere, theoretically combating ocean acidification and climate change at the same time. That’s the core premise of Subhas’s project, termed LOC-NESS for “Locking away Ocean Carbon in the North East Shelf and Slope.”

 

The Experiment, Updated

After taking initial measurements, the WHOI team will release the sodium hydroxide into the water alongside a nontoxic, inert red dye that allows them to track where it flows. The material will be poured into the wake of the boat to improve dilution, Subhas said.

Next, Subhas’s team will use an arsenal of drones, buoys, sensors, and nets across two boats to track the local environment’s response. These tools will monitor everything from nutrient levels and plankton abundance to ocean chemistry and water clarity, while measuring the water’s acidity and dissolved carbon dioxide. A NOAA protected species observer will be on board to scan for any marine mammals in the area.

The monitoring will continue for seven days, according to the EPA permit application, with scientists working in shifts to make continuous, 24-hour-a-day measurements. They anticipate the added alkalinity in the area of the experiment falling to undetectable levels within six days.

Besides the decrease in the volume of alkalinity being used in this trial, Subhas said several other changes in plans have been made in response to comments the EPA received during the previous permit application. The team is accelerating the mixing of sodium hydroxide with seawater by increasing the speed of the boat and using a seawater pump that will mix 200 liters of seawater per second into the alkalinity as it is added to the boat’s slipstream. Because of this, the EPA permit application states, the water’s pH should fall to safe levels within 12 seconds of application.

The move to the Wilkinson Basin is another change in plans. It is among the least biologically active areas of the northeast shelf, according to the permit application.

Ideas proposed by fishermen, tribal communities, and industry groups have had an effect, Subhas said. For example, it was thanks to comments from fishermen that the WHOI team expanded the monitoring to include copepods, as they are an important prey species for many fish.

When the LOC-NESS team submitted its previous permit application to the EPA last summer, the feedback was mixed. The application for this updated experiment, however, has been better received.

“I firmly believe that the risk of not carrying out experiments like this far exceeds any risk associated with the experiment itself,” wrote Larry Meyer, Director of the Center for Coastal and Ocean Mapping at the University of New Hampshire, one of several scientists among the 18 people posting comments so far.

Robert Rheault, executive director of the New Jersey-based Shellfish Growers Association, called the project a “much-needed, low-risk experiment.”