An image of a man in boots in a kelp hatchery
Since kelp grows as fast as two feet per day, it absorbs a huge amount of carbon through photosynthesis. (Jamie Walter / Running Tide)

Kelp  has featured in our pages frequently enough to be considered an important topic. It will be a partial solution to something big. Thanks, as always, to Robinson Meyer for the weekly newsletter that sometimes depresses the spirit but on other occasions, like this one, titled How to Fight Climate Change With Buoys That Look Like Ramen Noodles, points a small ray of hope in an unexpected direction:

Running Tide’s buoys are made of reclaimed waste wood, limestone, and kelp seedlings. (Jamie Walter / Running Tide)

Last month, somewhere off the coast of Maine, a small group of researchers and engineers released a series of tiny, floating objects into the water. The team called them “buoys,” but they looked more like a packet of uncooked ramen noodles glued to a green party streamer than anything of the navigational or weather-observing variety. These odd jellyfish had one role in life: to go away and never be seen again. With any luck, their successors would soon be released into the open ocean, where they would float away, absorb a small amount of carbon from the atmosphere, then sink to the bottom of the seafloor, where their residue would remain for thousands of years.

That is not only the goal. That is also the business model. The team worked for Running Tide, a Portland, Maine–based start-up that claims it can remove carbon dioxide from the ocean and atmosphere through the magic of kelp. Running Tide is one of a series of carbon-removal companies that have burst onto the market over the past few years with the hope of whisking heat-trapping pollution out of the atmosphere and locking it away for centuries. The most famous companies, such as Switzerland’s Climeworks or Canada’s Carbon Engineering, perform direct air capture, using common industrial processes to chemically clean carbon from the air. But this is not the only approach: Some firms have tried to store carbon in stone or concrete; others have tried to accelerate the rock-weathering process that normally takes thousands of years.

And then there’s kelp. Kelp grows as fast as two feet a day, which means it absorbs a huge amount of carbon through photosynthesis. That kelp could then be harvested, disposed of, or allowed to naturally drift to the bottom of the ocean. It has seemed like the perfect natural tool to sop up carbon from the ocean and atmosphere. But that has made me suspicious. The idea that humanity will remove carbon dioxide from the atmosphere by growing kelp smacks of the same naivete in the idea that we can solve climate change by growing trees or living in harmony with nature.

So I was pleasantly surprised when I met the leaders of Running Tide earlier this month. Far from having a hippie-dippie-ish enthusiasm about kelp, they spoke like engineers, aware of the immense scale of carbon removal that stands before them. While much of Running Tide’s science remains unvetted, the researchers seem to be thinking about all the right problems in all the right ways—approaching carbon removal as an organization-level problem rather than a one-off process.

At its core, carbon removal is “a mass-transfer problem,” Marty Odlin, Running Tide’s CEO, told me. The key issue is how to move the hundreds of gigatons of carbon emitted by fossil fuels from the “fast cycle,” where carbon flits from fossil fuels to the air to plant matter, back to the “slow cycle,” where they remain locked away in geological storage for millennia. “How do you move that?” Odlin said. “What’s the most efficient way possible to accomplish that mass transfer?” The question is really, really important. The United Nations recently said that carbon removal is “essential” to remedying climate change, but so far, we don’t have the technology to do it cheaply and at scale.

Odlin, who comes from a Maine fishing family and went to college for robotics, founded Running Tide in 2017 on the theory that the ocean, which covers two-thirds of the planet’s surface, would be essential to carbon removal. At least for now, the key aspect of Running Tide’s system are its buoys. Each buoy is made of reclaimed waste wood, limestone, and kelp seedlings, materials that are meant to address the climate problem in some way: The wood represents forest carbon that would otherwise be thrown out or incinerated, the limestone helps reverse ocean acidification, and, most important, the kelp grows ultrafast, absorbing carbon from the land and sea. Eventually, the buoy is meant to break down, with the limestone dissolving and the wood and kelp drifting to the bottom of the seafloor…

Read the whole newsletter here.