Tiny, invisible swirls and twirls, not much bigger than a coin, deep below the ocean’s surface are silently shaping some of the biggest forces affecting our climate: sea level rise, fisheries collapse, extreme flooding, and how much carbon dioxide the ocean absorbs.

An international research team led by the University of Cambridge found that deep ocean turbulence, the process that distributes heat, nutrients and carbon from the surface to the seafloor and back, affects our lives not on a scale of thousands of years as was previously thought, but within the span of a human lifetime. However, the tools used to predict these effects and inform policy do not adequately represent this turbulence, or the speed at which it moves. The results are reported in the journal Nature Communications.

Changing turbulence patterns could affect our climate in tangible ways, which is why this type of ocean monitoring is key: if nutrients are not being pulled from the deep ocean to the surface, it could cause marine food chains to break down, which would in turn cause fisheries to collapse. The way that heat is transferred from the deep ocean to shallower waters and back affects how Arctic and Antarctic ice melts, which affects sea level rise, storm intensity and flooding levels.

“There is a microphysics of the ocean, similar to cloud physics, that is extremely difficult and expensive to observe, but it governs our lives on human-relevant timescales,” said lead author Dr. Laura Cimoli from Cambridge’s Department of Applied Mathematics and Theoretical Physics. “We need the tools we use to predict these effects to be as accurate as possible, and we found that’s currently not the case.”

Tracking Chemical Ghosts Across the Ocean

One of the tracers the researchers used to test the accuracy of climate models was CFC (chlorofluorocarbon) concentration. CFCs were released into the atmosphere in large quantities before being banned in the 1980s under the Montreal Protocol, due to the damage they caused to the ozone layer. The researchers tracked how far and how fast CFCs have travelled over the past six decades by measuring their concentration at depth, and found some deep waters have carried CFCs all the way from Antarctica to the mid-Pacific and north Indian Ocean in just 40 years. The same waters also carry carbon, oxygen, and heat, and as they mix with other waters, turbulence becomes key to how much tracers, heat, and carbon remain trapped in the deep ocean and on what time scales.

“If I think about what matters most on human timescales, it’s three things: marine nutrients and ecosystems, which impact food security; Arctic changes, which have direct geopolitical implications and almost immediately affect extreme weather and flooding in the UK; and mixing of the deep southward flows feeding warm water to Antarctic ice shelves, which drive sea level rise,” said co-author Dr. Ali Mashayek from Cambridge’s Department of Earth Sciences.

Another experiment involved injecting dye into the deep ocean at known locations and depths and tracking its movement. In a deep canyon in the Rockall Trough, not far from UK waters, the dye rose as much as 100 metres per day, roughly 10,000 times faster than models predicted. When comparing the CFC, dye, and other observational data with climate models, the team found that the models’ output often deviated significantly from the observational data.

“This shows that climate models are not reliably capturing key effects of deep ocean turbulence,” said co-author Professor Colm-cille Caulfield, also from DAMTP. “If we’re going to make these models more useful for decision-makers, we will need to understand the underlying fundamental physical processes much better, develop better approximations that capture all those processes in computationally efficient ways that can be embedded in climate models straightforwardly, and test and constrain the outputs of the approximations with much more observational data.”

“It used to be that turbulence in the ocean interior was thought of as deep, distant and too slow to matter on human-relevant timescales, but there is increasing evidence that’s not always the case,” said co-author Professor Alberto Naveira Garabato from the University of Southampton. “The deep ocean can interact with the atmosphere on short timescales, and we need reliable tools to help us measure it.”

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Journal: Nature Communications
DOI: 10.1038/s41467-026-73809-3
Article Title: Climatic Reach of Small-Scale Turbulence in the Ocean Interior
Publication Date: 9-Jul-2026
Funding: Schmidt Sciences LLC; Advanced Research and Invention Agency (ARIA); Natural Environment Research Council (NERC); Engineering and Physical Sciences Research Council (EPSRC)