"A second paper, published earlier in the week by the journal Nature Geoscience, provides insight into how the disposal service in the ocean is actually working. The surprising finding is that a handful of relatively concentrated spots in the Southern Ocean account for a high proportion, roughly 20 percent, of the entire oceanic carbon uptake.
The reason is that while carbon dioxide can easily dissolve out of the air into ocean water, it tends to stay in a surface layer that does not mix well with the colder, denser water below. It can even escape that surface layer to re-enter the atmosphere. The scientists found that certain combinations of winds and currents are required to overcome the barrier and pump carbon dioxide into the deep ocean, where much of it stays locked away for thousands of years."
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The scientists used measurements from the new Argo network of floating robots to make the most complete analysis yet of the role of currents.