Tropical Teleconnection Impacts on Antarctic Climate Changes
Over the modern satellite era, substantial climatic changes have been observed in the Southern Ocean and the Antarctic. This study aims to summarize tropical teleconnections to the Southern Hemisphere high latitudes arising from the El Niño-Southern Oscillation, the Interdecadal Pacific Oscillation, and the Atlantic Multidecadal Oscillation. Particular focus is given to understanding the physical mechanisms of teleconnections and understanding their long-term climatic impacts. By synthesizing the results from numerous past studies, we find that tropical-to-polar teleconnections have contributed to the following Antarctic and Southern Ocean changes over the past few decades: regional rapid surface warming; pre-2015 sea-ice expansion and its reduction thereafter; changes in ocean heat content; accelerated thinning of the Antarctic ice sheet.
Limited observations and model biases restrict our understanding of the relative importance of teleconnections versus those arising from greenhouse gases, ozone recovery, and internal variability. Reducing these uncertainties and improving understanding requires pan-Antarctic efforts towards sustained, long-term observations and more realistic dynamics and parameterizations applied within high-resolution climate models.
Over the modern satellite era, substantial climatic changes have been observed in the Antarctic, including atmospheric and oceanic warming, ice sheet thinning, and a general Antarctic-wide expansion of sea ice, followed by a more recent rapid loss. Although these changes, featuring strong zonal asymmetry, are partially influenced by increasing greenhouse gas emissions and stratospheric ozone depletion, tropical–polar teleconnections are believed to have a role through Rossby wave dynamics. In this review, we synthesize an understanding of tropical teleconnections to the Southern Hemisphere extratropics arising from the El Niño–Southern Oscillation, Interdecadal Pacific Oscillation, and Atlantic Multidecadal Oscillation, focusing on the mechanisms and long-term climatic impacts. These teleconnections have contributed to observed Antarctic and Southern Ocean changes, including regional rapid surface warming, pre-2015 sea-ice expansion and its sudden reduction thereafter, changes in ocean heat content, and accelerated thinning of most of the Antarctic ice sheet. However, due to limited observations and inherent model biases, uncertainties remain in understanding and assessing the importance of these teleconnections versus those arising from greenhouse gases, ozone recovery and internal variability. Sustained pan-Antarctic efforts towards long-term observations, and more realistic dynamics and parameterizations in high-resolution climate models, offer opportunities to reduce these uncertainties.