US scientists poured 16,500 gallons of lye & bright pink dye into Gulf of Maine in first-of-its-kind 2025 experiment. Surprising reason has everything to do with climate change

A research vessel in the Gulf of Maine carried out an unusual experiment in August 2025, releasing 16,500 gallons of diluted sodium hydroxide (lye) into the ocean while a plume of bright pink dye spread across the water. Although the vivid pink patch appeared alarming, scientists said it was deliberately used to track the movement of treated seawater during the first federally permitted open-water ocean alkalinity enhancement (OAE) experiment in the United States.

As reported by TOI, the trial was led by researchers from the Woods Hole Oceanographic Institution (WHOI) as part of the LOC-NESS (Locking Ocean Carbon in the Northeast Shelf and Slope) project. According to the researchers, the aim was to determine whether increasing the ocean's alkalinity could help it absorb more carbon dioxide from the atmosphere while reducing the effects of ocean acidification. The experiment was designed to collect real-world data on how the process behaves outside laboratory conditions.

Why did scientists pour lye into the ocean?

The experiment focused on ocean alkalinity enhancement, a proposed carbon removal strategy that could increase the ocean's ability to absorb atmospheric carbon dioxide.


Scientists explain that the world's oceans already absorb around one-quarter of global carbon dioxide emissions, helping to slow climate change. However, as more carbon dioxide dissolves in seawater, the water becomes increasingly acidic. This process affects marine organisms such as oysters, clams, corals and plankton by making it more difficult for them to form calcium carbonate shells and skeletons.

During the Gulf of Maine trial, researchers gradually released diluted sodium hydroxide into the surface waters. The sodium hydroxide reacted with carbon dioxide already dissolved in seawater, converting it into bicarbonate ions, which are the most stable and abundant form of dissolved carbon in the ocean.

Why was bright pink dye released alongside the lye?

Scientists released bright pink rhodamine dye together with the sodium hydroxide purely as a tracking tool.

The dye allowed researchers aboard a second vessel to observe how the treated seawater mixed with the surrounding ocean. Throughout the six-hour experiment, the research team continuously monitored pH, alkalinity and other chemical properties to understand how the treatment dispersed under natural ocean conditions.

Researchers said the scientific basis for ocean alkalinity enhancement is supported by studies published in Nature Climate Change, which suggest the technique could become an important carbon dioxide removal strategy if environmental impacts, verification methods and large-scale deployment challenges are carefully addressed.

Why was the experiment conducted in the open ocean?

Most previous ocean alkalinity enhancement research had been limited to computer simulations, laboratory experiments and small-scale coastal studies.

According to the researchers, conducting the experiment in the Gulf of Maine allowed them to observe how the process behaves under realistic ocean conditions, where tides, currents and marine ecosystems are significantly more complex.

The project underwent several years of planning before receiving approval from the US Environmental Protection Agency (EPA). Researchers also consulted fishermen, environmental organisations, regulators and local communities before carrying out the trial. During the experiment, marine mammal observers remained on duty while scientists monitored chemical changes to ensure environmental limits were not exceeded.

Why was the Gulf of Maine chosen?

Scientists selected the Gulf of Maine because it supports economically important shellfish fisheries while also experiencing the effects of climate change, including changes in ocean chemistry.

Research published in Scientific Reports has found that although shifts in ocean circulation have delayed severe acidification in the region, this natural buffering effect may not continue indefinitely. Researchers believe this makes the Gulf of Maine an important location for studying potential methods to reduce future ocean acidification.

The scientists also stressed that the experiment was not intended to demonstrate large-scale carbon removal. Instead, its purpose was to validate computer models, improve monitoring techniques and determine whether ocean alkalinity enhancement can be measured accurately and safely under real-world conditions.

What does this experiment mean for climate research?

Ocean alkalinity enhancement has attracted increasing attention because it could potentially remove carbon dioxide while also reducing ocean acidification.

Unlike some carbon capture technologies that require underground storage, much of the captured carbon remains dissolved in seawater as bicarbonate ions, where it can remain for thousands of years as part of the ocean's natural carbon cycle.

However, researchers caution that important questions remain unanswered. Scientists say further research is needed to understand how repeated alkalinity enhancement could affect marine ecosystems, ocean chemistry and coastal food webs if deployed on a much larger scale. They also note that more work is required to assess costs, energy requirements and reliable methods for verifying how much carbon dioxide is permanently removed from the atmosphere.

Many climate scientists also emphasise that carbon removal technologies should complement, rather than replace, efforts to rapidly reduce greenhouse gas emissions.

Inputs from TOI