Adventures in the Antarctic: Sensitivity, Orography, and Emergence of Climate Change at a Pole Far, Far Away
Abstract
The changing climate over the Antarctic is less documented and understood than that over the Arctic. Unlike the Arctic, where retreating sea ice, declining snow cover, and lower tropospheric warming are all evident today, climate change over the Antarctic has been more heterogeneous: expansion of sea ice cover accompanied by warming of the subsurface Southern Ocean, and cooling and growth of the East Antarctic Ice Sheet accompanied by warming and retreat of ice shelves lining the West Antarctic Peninsula. Here, we present an overview of a series of modelling studies that aim to understand this mixed climate change signal over the Antarctic. First, we demonstrate that weaker transient climate change over the Antarctic (relative to the Arctic) is not only a result of heat uptake into the deep Southern Ocean, but also a consequence of less destabilizing radiative feedbacks and, consequently, weaker regional climate sensitivity. Next, we show that some of this weaker sensitivity arises from the orography of the Antarctic Ice Sheet, which blocks advection of temperature and moisture anomalies into the continental boundary layer, and thereby decreases the strength of the high-latitude lapse rate feedback. Finally, we show that Antarctic sea ice expansion over the observational era (1979 to 2015), which occurred even as atmospheric CO2 increased and the rest of the globe warmed, can plausibly be explained by the lengthy time of emergence of the climate change signal over the Antarctic: the low intrinsic sensitivity and strong natural variability characterizing the region can result in surprising periods of sea ice expansion. Overall, our work highlights how climate change over the Antarctic will be play out substantially differently than over the Arctic, and that these differences may be understood to arise from innate differences in regional sensitivity and natural variability between the two poles.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMGC12A..06S
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 3339 Ocean/atmosphere interactions;
- ATMOSPHERIC PROCESSES;
- 0750 Sea ice;
- CRYOSPHERE;
- 0764 Energy balance;
- CRYOSPHERE