The ocean's deep, hidden currents are having a profound impact on our climate, and it's about time we pay attention. Tiny waves in the deep ocean, often overlooked, are now revealed to have a significant influence on global climate patterns, even over short timescales. This revelation challenges long-held assumptions that deep ocean turbulence only mattered over centuries to millennia. Our research, published in Nature Communications, highlights how these small-scale movements can affect heat, carbon, and nutrient transfer between the atmosphere and ocean, with far-reaching consequences. Imagine a single year's worth of these tiny waves, and you'll grasp the magnitude of their impact. The presence of chlorofluorocarbons (CFCs) in the ocean, once used in refrigerants and aerosols, provides a unique window into these processes. By measuring CFC concentrations at depth, we can calculate how long it's been since deep waters last mixed with the surface and how quickly they've moved around the globe. In just 40 years, CFCs have traveled from Antarctica to the mid-Pacific and north Indian Ocean, a testament to the ocean's dynamic nature. But it's not just about CFCs. Experiments using dyes injected into the ocean have shown that deep waters can rise towards the surface, climbing as much as 100 meters a day. This vertical movement is crucial for nutrient distribution, which underpins the marine food web. If these nutrients aren't pulled from the deep ocean to the surface, entire ecosystems and global fisheries could collapse, impacting global food security. The transfer of heat from the deep ocean to shallower waters also affects Arctic and Antarctic ice melt, sea level rise, storm intensity, and flooding levels worldwide. Yet, current climate models fail to capture these small-scale processes accurately. They underestimate the mixing and vertical movement of water, relying on outdated parameterizations that date back to the 1990s. This is a critical issue, as tiny physical events in the ocean can have outsized impacts on the climate, much like cloud formation. To improve our models, we need to update parameterizations with our enhanced understanding of deep ocean mixing. While observing small-scale mixing is challenging, we've made significant progress in the past decade through regional and global observation programs and advancements in high-performance computing. However, we still face obstacles in fully understanding the climate's intricacies. As mixing observations remain rare, we must find innovative ways to overcome this bottleneck and allocate resources efficiently to accelerate progress. The ocean's deep currents are a missing piece of the climate puzzle, and it's time we give them the attention they deserve.
