Twice as much carbon sinks into the ocean as previously thought

THE “BIOLOGICAL pump” in the world’s oceans, which plays a key part in the global carbon cycle, is capturing twice as much carbon as previously thought, scientists have said.

The biological carbon pump (BCP) contributes to the role of the ocean in taking up and storing carbon dioxide (CO2) by removing the gas from the atmosphere, changing it into living matter, and distributing it to the deeper ocean layers.

Without the BCP, the atmospheric concentration of CO2 would be much higher.

The researchers said their findings, published in the journal Proceedings of the National Academy of Sciences, could have implications for future climate assessments.

Single-celled organisms, called phytoplankton, live on the ocean’s surface and use sunlight to make food and energy – taking up CO2 and releasing oxygen in the process. When they die, they are eaten by other marine creatures, like zooplankton. And once these creatures die, they become biological debris, known as marine snow, that are rich in carbon and fall deeper into the ocean, a key process in the BCP.

However, the phytoplankton’s ability to absorb C02 depends on the amount of sunlight able to penetrate the ocean’s upper layer.

Researchers set out to measure the depth of the ocean’s sunlit surface area or euphotic zone, and foundits depth, which is where most of the marine species live, to significantly vary throughout the world.

The authors were able to estimate the rate at which carbon particles are sinking.

They found that about twice as much carbon sinks into the ocean per year than previously estimated.