How Running Tide Removed 25,416.25 Tonnes of CO2 in 2023

At Running Tide, we have spent the last seven years building off the best available science to develop the technology capable of safely amplifying and accurately measuring the natural flow of carbon into the deep ocean. 2023 was the year we got to work and started removing carbon.

  • First-of-a-kind carbon removal credits: Delivered 21,778 carbon removal credits to 25+ enterprise customers including Shopify, Microsoft, and Stripe and more than 12,000 grassroots supporters through our partnership with Patch, with more to be delivered.  
  • First-of-a-kind permit: Running Tide received a first-of-its kind permit for ocean carbon removal from the government of Iceland.
  • First-of-its-kind scale: In 2023, we removed more CO2 than any organization on the planet while advancing our understanding of the ocean. 
  • First-of-its-kind Ocean CDR MRV platform: We developed our MRV platform with a combination purpose-built hardware, software, and models to measure and monitor our system in the open ocean and verify with a high  how much CO2 we removed.

Here’s how we did it:

  • What: 15 deployments of alkaline carbon buoys, composed of wood coated in limestone (CaCO3) and lime kiln dust.
  • Where: Deployed south and west of Iceland in the North Atlantic within Iceland’s EEZ. The buoys floated for three weeks on average and dispersed over thousands of square miles before sinking nearly a mile to the ocean floor.
  • When: Deployments conducted from May through August of 2023. 
  • How: Under a research permit from the Icelandic government, monitored by our fleet of nearly 500 custom verification sensors that fed over 4 million data points into our models, allowing us to conservatively measure how much CO2 was removed while maintaining 99.8% uptime. 

The Story

Over the last 150 years we have moved trillions of tons of carbon out of long term storage in the earth, burned it, and transferred it to the atmosphere, where it has spread out through the entire fast carbon cycle. It’s in the oceans, in trees, and in every living thing on earth. This transfer has created an imbalance in the carbon cycle, as it has shifted stable slow carbon to volatile fast carbon - warming the planet, acidifying the oceans, and creating more volatile weather patterns.  The increase in volatility in the carbon cycle has increased the volatility in our climatic system, directly impacting all life on earth. 

The job of carbon removal is to remove that volatility by transferring fast carbon back to slow. That is what Running Tide has set out to do, and in 2023 we got the first chance to do it at a large enough scale to further our research and development effort to build a nature-based system that can sustainably amplify earth's natural processes with the help of our largest and most powerful carbon removal ally: the ocean. 

Roughly 20 years ago, tree farmers in Nova Scotia planted a combination of soft and hardwood trees to support the local paper and timber industries. Each year, those trees grew and converted roughly 0.9 tons of CO2 per ton of wood into oxygen and carbon stored in the wood. This past year those trees were harvested, and the forests were prepared to be replanted. Not all parts of the tree are usable for traditional commercial purposes and that carbon-rich “residue”— typically a waste product— would otherwise have been burned or left to rot. Instead of letting that carbon return to the atmosphere and remain in the fast carbon cycle as CO2, Running Tide took 38,000 tons of carbon-rich wood and shipped it to Iceland. There, we processed the wood into “carbon buoys,” tiny chunks of wood that were coated in a mixture of alkaline minerals. 

We loaded these buoys onto a ship and released them into the North Atlantic Ocean, where they floated on the ocean’s surface for 3-4 weeks, drifting with ocean currents for hundreds of miles as the alkaline mineral coating dissolved. We designed our system to spread out, minimizing the concentration in any one place (more on this in a minute). They were also designed to eventually lose their battle with gravity and to sink to more than a mile below the ocean’s surface. There, the carbon in the wood will stay locked away from the atmosphere and the surface of the ocean for hundreds to thousands of years. 

Importantly, the buoys were designed to not (and ultimately didn’t) all sink in one spot. Spreading them out was essential to avoid oversaturation of carbon (and wood) on any part of the ocean floor. When the wood reaches the ocean floor, it either is eaten by deep sea creatures or is buried in the mud, where it can become oil or coal (again) millions of years from now. Either way, that ‘fast’ carbon that was sequestered briefly in the trees is now locked away in the slow carbon cycle from hundreds to thousands of years, where it no longer contributes to global warming and ocean acidification. In short, if it gets to the bottom of the ocean, the volatility is removed.  

This process mimics what nature has done for millions of years – transferring terrestrial biomass from land, through rivers, to the open ocean – where they serve as critical habitats and foster improved biodiversity at the bottom of the ocean.

Aided by 4 million in-situ data points from our fleet of nearly 500 sensor buoys and armed with the best available ocean science, our team ran calculations and analyses to corroborate that not only did we successfully remove 25,416.25 tons of CO2 (and counting), but also that the final density of the sunk wood amounts to a literal drop in the ocean – about two tablespoons of carbon per square meter of the ocean floor. 

Why this matters

Our ‘drop in the ocean’ represents the most tons of CO2 durably removed from the surface of the planet by humans on purpose in a single year, ever. It also demonstrates how we can leverage Earth’s natural systems alongside human engineering and ingenuity to meaningfully address the climate crisis. 

Scaling carbon removal now matters because without significant, science-backed, well substantiated, durable deliveries, carbon removal makes little to no difference.

Outside of traditional nature-based projects like reforestation, the carbon removal industry as a whole has removed less than 1 million tons of CO2 so far. That is functionally less than a drop in the bucket. 

Meanwhile, the IPCC’s Sixth Assessment Report tells us that all reasonable scenarios that limit global warming to 1.5°C — a globally accepted limit beyond which the planet is likely to face dire and unpredictable consequences — require large-scale carbon removal to the tune of six to ten gigatons annually by 2050, in addition to the immediate reduction of CO2  emissions across all economic sectors. Yes, we need decarbonization, but we also desperately need to build up massive scale carbon removal capabilities – and we needed it yesterday.

That’s an order of magnitude challenge; we need to scale carbon removal by factors of 1,000-10,000x. It’s important we start now, and work with natural systems to achieve that scale. The ocean is the center of our climate system, and the largest active carbon reservoir on the planet. Solutions that partner with the ocean to remove and store carbon have the potential to scale to billions of tons annually by leveraging the natural carbon removal pathways the ocean provides. Our deliveries represent key milestones, including the largest ocean-based carbon removal research project, and are key to proving ocean-based carbon removal can scale responsibly. 

Running Tide is excited to be at the forefront of scaling carbon removal in a data-driven, conscientious, science backed way. We’re delivering tons to customers like Microsoft and Shopify who have an incredibly high bar for quality and veracity. We will continue to deploy in 2024, learning (and sharing) as we go, and scaling our ability to cycle carbon from fast to slow.

If you want to join the slow carbon movement and work with us let us know.

Additional detailed resources can be found at

How Running Tide Removed 25,416.25 Tonnes of CO2 in 2023
Jordan Breighner
May 2, 2024
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