Climate and marine scientists have so far been unable to provide satisfactory explanations as to why parts of the Southern Ocean have bucked the trend of global warming. Now a group of scientists from ETH Zurich and Princeton University has solved the puzzle with the help of simulations with a high-resolution ocean model.
In a paper published recently in the journal AGU Advances, the scientists use a series of simulations to show that sea-ice changes are the most probable cause for the cooling of the surface waters in the Southern Ocean. Only when AOS Postdoctoral Research Fellow Alex Haumann, lead author and ETH Zurich Professor Nicolas Gruber’s former doctoral student, and the team incorporated the observed changes in sea ice into the model were they able to correctly replicate the observed pattern of the temperature changes. When they omitted this effect and only took into account the other potential factors – such as a more vigorous ocean circulation or increased freshwater fluxes from the melting of the Antarctic glaciers – the pattern was not accurately simulated.