The machine, which will be commissioned later this year, grinds limestone and releases it into the West River Pictou, creating murky water that dissolves within minutes. This process could significantly affect carbon dioxide (CO2) levels in the atmosphere by converting the gas into stable molecules that remain trapped underwater for thousands of years.

Eddie Halfyard, a freshwater ecologist and co-founder of CarbonRun, explains to the NYT : “The beauty of this technology is its simplicity. The water does most of the work.” The $400,000 project is the start of a broader effort by CarbonRun to build more machines with the goal of reducing the global carbon footprint.

The science behind the technology

Rivers naturally release CO2 into the atmosphere, contributing to global warming. By adding limestone to rivers, CarbonRun's technology changes the chemical composition of the water, converting CO2 into bicarbonates that remain dissolved in the water and eventually reach the oceans, where they are trapped. This natural process, known as increasing alkalinity, could contribute significantly to the global fight against climate change.

Nan Ransohoff, head of the Frontier Fund, which is backed by tech giants like Stripe and Alphabet, says: "The potential to remove carbon from the oceans is huge and underexplored."

From idea to action

On Monday, Frontier announced a $25 million investment in CarbonRun, with the goal of removing more than 55,000 tons of CO2 from the atmosphere — the equivalent of the annual emissions of 13,000 cars. If successfully scaled, this method could remove billions of tons of carbon annually.

However, CarbonRun's efforts face challenges. While the technology is proven effective in rivers, its application on a global scale or in unpredictable oceans is much more complex. In addition, scaling this operation would require huge amounts of limestone, which could lead to new environmental problems associated with mining and transportation.

The road ahead

Changing ocean chemistry remains a controversial issue. Some environmental groups have expressed concern that interfering with marine ecosystems could have unintended consequences. However, many scientists argue that such interventions may be necessary to avoid catastrophic climate change.

Ken Buiseler, a senior scientist at the Woods Hole Oceanographic Institution, said: "All of these methods have their problems and consequences, but we have to weigh them against the consequences of doing nothing, which to me is catastrophic."

CarbonRun, however, has already managed to gain support from the local community. In public meetings with local residents and Nova Scotia's First Nations, the startup pointed to the environmental benefits that river liming has already brought to fish populations, particularly in reviving salmon in once-acidic rivers.

Sheet Harbor resident Donald Rutledge witnessed the return of salmon to the Killagh River after a similar liming operation. "Now I can fish with my grandson." It means a lot to me," he said, expressing hope that the technology will be expanded.

Scaling technology

While river desalination has shown promise, scaling the ocean treatment technology remains a formidable task. Open water is more turbulent, and the effects of adding alkalinity are difficult to measure. Still, companies like CarbonRun continue to operate, knowing that the development of this technology is crucial in the fight against climate change.

With increasing interest in removing carbon from the oceans, more and more scientific research is being done. Teams at Dalhousie University in Halifax are working to verify whether these methods can safely and effectively remove carbon on a large scale.

As the world faces increasingly urgent climate challenges, projects like CarbonRun represent both hope and a sense of urgency. They are racing against time to develop new methods to remove excess carbon from the atmosphere while balancing risks and complexities.

"We owe it to future generations at least one part of the planet that we haven't ruined," said Lisa Levine, a marine ecologist at the Scripps Institution of Oceanography. The question is whether CarbonRun and similar companies can find a balance between preserving the planet and protecting its ecosystems.