A research team from The Norwegian Research Centre (NORCE) have revealed a new relationship for climate models that links both carbon and heat uptake with water-column stability in the Antarctic Ocean.
This climate model projections study, published in Nature Communications, was conducted by researchers from NORCE Norwegian Research Centre, and the Bjerknes Centre for Climate Research in Bergen, Norway. The research team consisted of Timothée Bourgeois, lead author of the study, and his colleagues Nadine Goris, Jörg Schwinger, and Jerry F. Tjiputra.
What role does the ocean play regarding climate change?
The ocean is a powerful mitigator of climate change; scientists have discovered that it absorbs about 25% of the CO2 emitted by humans into the atmosphere. This is also known as ‘anthropogenic carbon’, and 90% of this excess heat is caused by global warming.
One of the hotspots for the detection of anthropogenic carbon, and excess heat uptake is the Antarctic Ocean.
How were the climate models developed?
Scientists observed a region of the Antarctic Ocean, where a key mechanism called ’ocean subduction’ was notably located between 30°S and 55°S. This permitted the efficient transfer of anthropogenic carbon, and excess heat from the surface to the depths of the ocean, where it could be stored for centuries.
Climate model projections of these carbon and heat sinks still remain highly uncertain. Reducing such uncertainties is necessary to effectively guide the development of climate mitigation policies for meeting ambitious climate targets.
Bourgeois explained: “Climate models have significantly improved on many aspects during the last decades, yet they still show some biases that we must reduce.
“Models with a more unstable water column have an efficient subduction mechanism and a strengthened carbon and heat uptake in our region of interest.”
What does this mean for the future?
The research team discovered that models with a stable or ‘stratified’ water column revealed reduced subduction and decreased uptakes.
Therefore, utilising recent statistical methodology and observational data describing today’s water-column stability, the new relationship allows scientists to reduce the uncertainty of future estimates regarding the anthropogenic carbon uptake by up to 53%, and the excess heat uptake by 28%.
These results emphasise that, for this region, an improved representation of the water-column stability in climate models is key to improving climate change projections.