Rising emissions and temperatures will threaten Antarctica’s chemical, physical, and biological systems.
PolarRES seeks to investigate the Ocean-Atmosphere-Ice (O-A-I) interactions in the Antarctic region to understand how the Antarctic coupled climate system will evolve with global and local-scale climate change. Whilst melting of the Antarctic ice sheet is a primary concern, other key scientific questions surround the potential implications of physical and chemical disturbances to the Southern Ocean marine ecosystem. For example, increasing greenhouse gas emissions have already led to a higher intake and accumulation of CO2, advancing ocean acidification. Processes which link the climates of Antarctica with the Southern Hemisphere mid-latitudes are also being studied closely, as changes due to global warming need to be understood to help reduce uncertainty in regional climate change projections.
We are currently exploring eight different storylines (four respectively for summer and winter) for the Southern Hemisphere. Each storyline is a plausible outcome conditional upon different possible future changes in Antarctic sea ice loss and upper atmospheric circulation. These two factors exert significant but largely unrelated controls over the regional response to climate change in the Antarctic.
The storylines are derived from the latest suite of state-of-the-art climate models from CMIP6. Models disagree over the amount of sea ice retreat into the future and the wintertime strengthening or delay in the spring breakdown of the stratospheric polar vortex (a high-altitude westerly circulation between ~10 and 50 km surrounding Antarctica). Following an in-depth evaluation of model performance in the recent past, we were able to exclude models deemed unlikely in simulating the future end-of-century (2070-2099) climate.
In addition to exploring both the atmospheric and terrestrial impacts of the storylines, we will also assess changes in ocean properties and their implications for the Southern Ocean marine ecosystem, with extra focus on the important biodiverse South Scotia Sea region. Storylines of primary focus include:
- High sea ice loss and early polar vortex breakdown delay
- Low sea ice loss and later polar vortex breakdown delay
- High sea ice loss and weak polar vortex strengthening
- Low sea ice loss and strong polar vortex strengthening.
These storylines are selected for further investigation using regional climate models and were chosen on the basis of most contrasting climate-related storyline impacts. Investigations are ongoing to quantify the propensity for future marine heatwaves to occur under each contrasting storyline, tied to expected changes in aquatic species’ distribution (e.g., phytoplankton, krill etc.).