Deep ocean micro-turbulence affects climate faster than thought, study finds

Miniscule swirls of water in the ocean depths are distributing heat, carbon and nutrients across the planet much faster than scientific models have estimated, with major implications for our understanding of environmental threats, according to landmark research led by Murray Edwards Bye Fellow Dr Laura Cimoli.
The new analysis of the effect of mixing generated by deep ocean turbulence has revealed significant flaws in the measurement of key processes, such as how much heat reaches Antarctic ice shelves or the level of climate-affecting carbon entering the deep ocean.
Mixing could affect these climatic changes that will harm humans far more rapidly than has been thought, the international research team’s study, reported in the journal Nature Communications, concludes.
Forces such as sea level rise, the planetary warming caused by excess carbon dioxide, fisheries collapse and extreme flooding will affect humanity within a single lifetime, not over hundreds or thousands of years as mathematical models had predicted.
Accurate forecasting is vital to predict the effects of turbulence and inform policy. Instead of traditional computer modelling, scientists in the latest study used a combination of previously collected physical and chemical measurements, including an experiment that involved injecting dye into the deep ocean and tracking its movement.
Ocean turbulence is caused because waves form and break not only at the shore, but throughout the whole water column down to the seafloor, explained Laura, of Cambridge’s Department of Applied Mathematics and Theoretical Physics (DAMTP).
‘When they break, they generate turbulence and mixing (you would know the "feeling" of mixing if you have ever found yourself caught in a big wave breaking at the beach!). This process leads to the mixing of anything carried by the water, such as heat, carbon, oxygen and nutrients, thus affecting ocean dynamics and biology.’
Though the small-scale turbulence is not the generator of change, it amplifies and directs its impact. ‘Small-scale turbulence in the ocean interior is like the trim tab on a ship’s rudder. A trim tab is a small flap attached to the rudder. It is not the engine, and it is not the main force moving the ship, but by adjusting the rudder it can significantly affect the ship’s direction.
‘Similarly, our findings show that small-scale turbulence can significantly alter several short-to-long climate processes, even if it is not always the main engine behind such processes.’
The consequences were serious, she added. ‘In particular, without a proper representation of turbulence, we are getting the distribution of many properties - such as heat, carbon, nutrients and oxygen – wrong, sometimes on a large scale. The cumulative effect of this mistake is important.
‘For example, it means we mis-represent how much heat or carbon are entering the deep ocean, thus affecting climate predictions, or we mis-represent how much heat reaches the Antarctic ice shelves, which are rapidly melting and an important contributor to global sea level rise. We cannot accurately predict how many nutrients will reach the surface to fuel biological productivity, which sustains the oceanic food webs and fishery activities; and we cannot properly quantify how much deep ecosystems are affected by ocean dynamics and will be perturbed by human activities, such as deep sea mining.’
The team, which also included Murray Edwards Fellow Alex Piotrowski, Professor of Paleoclimatology, concluded mathematical modelling will always struggle to represent small-scale turbulence because it takes place both quicky and in miniature. ‘We really need more [real life] observations to better quantify what other processes might be affected by mixing without us even knowing,’ Laura said.
Observing small-scale mixing, the 'microphysics of the ocean', is still challenging for scientists, but significant progress has been made over the past decades, she added. ‘We now have tools to measure it more accurately, autonomously, and for longer time-series. So, we need to work on collecting more of these observations, which are still very rare.’
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. They 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. As they travel, they mix with other waters, and so turbulence is key to how much tracers, heat, and carbon remain trapped in the deep ocean and on what time scales.
The findings come at a time when global ocean research of this kind is at risk. In May, the US National Science Foundation announced the dismantling of the Ocean Observatories Initiative, a $368 million ocean observation network that provides vital oceanographic data worldwide, although the plans were later reversed.
The research was supported in part by Schmidt Sciences LLC, the Advanced Research and Invention Agency (ARIA), the US National Science Foundation (NSF), the Natural Environment Research Council (NERC) and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI).
Reference:
Laura Cimoli et al. ‘Climatic Reach of Small-Scale Turbulence in the Ocean Interior.’ Nature Communications (2026). DOI: 10.1038/s41467-026-73809-3