Pulses of sinking carbon reaching the deep sea are not captured in global climate models

A new study shows that pulses of sinking debris carry large amounts of carbon to the deep seafloor, but are poorly represented in global climate models.

More than two miles below the ocean's surface, microbes, worms, fishes, and other creatures great and small thrive. They rely on the transport of dead and decaying matter from the surface (marine snow) for food at these dark depths.

Up near the sea surface, carbon dioxide from the atmosphere is incorporated in the bodies of microscopic algae and the animals that eat them. When they die, these organisms sink to the depths, carrying carbon with them.

This supply of carbon to the deep sea isn't steady. At times, months' to years' worth of marine snow falls to the abyss during very short "pulse" events.

In a new study published in the Proceedings of the National Academy of Sciences (PNAS), MBARI scientists and their collaborators show that there has been an increase in pulse events off the coast of California. They also show that, although such episodes are very important to the carbon cycle, they are not well represented in global climate models.

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