Winter currents funnel surface algae deep, boosting ocean carbon storage
Researchers have identified fast-moving winter currents as the cause of chlorophyll appearing over 1,000 m deep in the North Atlantic.
Between 2014 and 2017, Biogeochemical-Argo floats detected unusually high chlorophyll concentrations at depths exceeding 1,000 m in the subpolar North Atlantic, particularly in the Labrador and Irminger Seas. Scientists from the Institute of Marine Sciences and the Barcelona Supercomputing Center traced the phenomenon to winter-driven deep convection, a process where cold, wind-cooled surface water becomes denser and plunges downward.
High-resolution simulations on Barcelona’s supercomputers revealed that intense winter storms amplify this cascade, rapidly delivering living microalgae and organic particles to the deep ocean. Once at depth, some material is later carried laterally by deep currents, effectively sequestering carbon away from the atmosphere. The study estimates that this pathway accounts for 30-50 % of organic particles reaching 500-2,000 m during strong mixing events, highlighting a previously underappreciated component of the global carbon cycle.
Why it matters
The finding reveals a major natural mechanism that removes atmospheric CO₂, influencing climate models and future carbon budgeting.
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