CO2–Induced Ocean Climate Change around Antarctica in GFDL CM2.5 and CM2.6

We use two high resolution climate models recently developed at GFDL (CM2.5 and CM2.6) to investigate CO₂–induced ocean climate change around Antarctica and its implication for the Antarctic ice sheet melt. We consider both long-term control runs and the idealized 1% per year CO₂ doubling experiments. In particular, we focus on the role of three different mechanisms impacting the transport of heat from the ocean interior onto the continental shelf of Antarctica, which are responsible for the basal melt of ice shelves. Firstly, the southward shift of the westerlies in the doubling CO₂ experiments leads to a weakening of the easterlies near the continental edge, thereby decreasing Ekman downwelling. The decreased downwelling allows the transport of heat from the ocean interior onto the continental shelf. Secondly, the increase in surface wind velocity in the CO₂ experiments lead to more energetic mesoscale eddies and greater heat transport across the shelf break. Thirdly, the lower salinity of shelf water in the CO₂ experiments due to the freshwater addition and a decline in sea ice formation enhances baroclinicity near the shelf break and strengthens the Antarctic Slope Front current which behaves as a barrier to heat transport onto the continental shelf.