The amount of carbon locked away in the depths of the Southern Ocean could fall by almost 20 per cent by 2100 as warming waters lead to increased microbial activity, according to ARC-supported research at the Institute of Marine and Antarctic Science (IMAS) at the University of Tasmania.

The Southern Ocean absorbs a large proportion of heat and carbon dioxide from anthropogenic emissions, with billions of tonnes of carbon locked away as phytoplankton die and sink to the ocean floor. Modelling and laboratory-based experiments have predicted that ocean microbes will become more active as the climate changes, interrupting the flow of carbon to the seafloor.

For the first time, those predictions have been tested by field research in the Southern Ocean conducted by Dr Emma Cavan, supplying experimental data to improve climate modelling in the future.

The research forms part of a project led by ARC Australian Laureate Fellow, Professor Philip Boyd, who is investigating how the natural microbial activity of the Southern Ocean could be utilised to mitigate against the effects of anthropogenic climate change.

Research suggests that the change in activity of the microbial community could see increasing amounts of carbon dioxide recycled back into the atmosphere instead of being stored in the deep sea for many decades or centuries.

Image: Collecting microbes from the southern ocean on the RV Investigator.
Credit: Emma Cavan.