Agulhas Current Eddies Drive Coastal Climate Extremes
Get the Health newsletter
Daily health & science — research, biotech, public health, the studies worth knowing. Free.
- University of Miami and University of Southampton researchers published findings in Nature Climate Change showing that intensifying eddies in the Agulhas Current amplify climate extremes through two mechanisms — accelerating surface warming while enhancing hidden upwelling that cools deeper waters.
- Lisa Beal (University of Miami Rosenstiel School) and Kathryn Gunn (University of Southampton) built on a two-year high-resolution mooring dataset that recorded hourly velocity, temperature, and salinity measurements across the full depth and width of the Agulhas Current off southeast Africa.
- The Agulhas Current's surface waters are warming at three to four times the global ocean average, while eddies have kept deeper waters comparatively cool — a layered structure the researchers say helps explain increased rainfall in South Africa alongside a reported decline in the current's total heat transfer to higher latitudes.
- Both small frontal instabilities (~10 km across) and larger meanders pump deep, cold, nutrient-rich water onto the continental shelf, potentially enhancing productivity there, while farther offshore meanders trap heat and salt closer to the surface.
- The overall volume transport of the Agulhas Current remains stable despite these changes, meaning the disruption is driven by shifting eddy behavior rather than a weakening of the current itself.
- The researchers suggest the findings may provide a unifying explanation for observed changes in major ocean currents worldwide, including the Gulf Stream along the U.S. East Coast.
Why it matters: Coastal ecosystems from South Africa to the U.S. East Coast face compounding climate pressure as eddies drive surface warming three to four times the global ocean average, and the Agulhas Current's stable volume transport means this eddy-driven disruption cannot be reversed by stabilizing the underlying current — the source notes the same eddy mechanism may explain changes in the Gulf Stream.
