GISS Lunch Seminar, 2022-01-12 Speaker: Lettie Roach (GISS/Columbia Univ.) Title: Antarctic sea ice asymmetry Abstract: The mean seasonal cycle of Antarctic sea ice extent is asymmetric, with the period of ice retreat being nearly two months shorter than the period of ice advance. This feature is largely consistent in observations from year to year, across different satellite products, and for both sea ice extent and sea ice area. The asymmetry is also broadly reproduced by comprehensive climate models across generations from CMIP3 to CMIP6, with limited impacts from internal variability. Using a range of idealized climate models of varying complexity, I show that the asymmetry has a simple physical explanation that is markedly different from those proposed in previous studies. I will end by discussing some implications for the seasonality of Arctic sea ice.