A new study by researchers in Australia recently discovered a tiny predatory organism known as Prorocentrum cf. balticum, which can naturally sequester carbon thanks to its unique foraging strategy. The marine microbe is a mixotrophic protist that secretes a carbon-rich mucus to attract and trap other organisms for consumption. The mucus is then abandoned and sinks to the bottom of the ocean, where it contributes to the natural biological pump in the marine carbon cycle.

Researchers say the study of the abundant P. balticum is the first to demonstrate this type of behavior; they predict the microbe is capable of sinking up to 0.15 gigatons of carbon annually. According to senior author and Professor Martina Doblin, "the findings have global significance for how we see the ocean balancing carbon dioxide in the atmosphere.”

Why This Matters

Ten gigatons of carbon need to be removed from the atmosphere annually until 2050 to meet climate goals outlined in the Paris Agreement. The discovery of this new microbe indicates a new nature-based solution for carbon sequestration in the ocean that could keep the world on track to meet carbon level targets.

"The natural production of extracellular, carbon-rich polymers by ocean microbes under nutrient-deficient conditions, which we'll see under global warming, suggest these microbes could help maintain the biological carbon pump in the future ocean,” said Doblin. "This could be a game changer in the way we think about carbon and the way it moves in the marine environment.”

The Risks of Carbon Sequestration in the Ocean

The ocean is one of the world’s largest carbon sinks and stores around 38,000 gigatons of carbon (16 times the amount of carbon in the terrestrial biosphere). However, injecting carbon into the ocean to remove it from the atmosphere has been branded as the "world’s best bad idea.” Altering the careful balance of the ocean's biological carbon pump could cause irreversible damage to deepwater ecosystems in the long term, and severely impact calcification processes in both the upper and lower ocean. In 2006, the German Advisory Council on Global Change concluded that "introducing CO2 into seawater should be prohibited because the risk of ecological damage cannot be assessed and the retention period [of carbon] in the oceans is too short." Additionally, the focus on carbon sequestration in the ocean is a distraction from real solutions to climate change, including phasing out fossil fuels, developing alternative clean energies, and lowering emissions now.