E-Mail Sea ice cover in the Southern Hemisphere is extremely variable, from summer to winter and from millennium to millennium, according to a University of Maine-led study. Overall, sea ice has been on the rise for about 10,000 years, but with some exceptions to this trend. Dominic Winski, a research assistant professor at the UMaine Climate Change Institute, spearheaded a project that uncovered new information about millennia of sea ice variability, particularly across seasons, in the Southern Hemisphere by examining the chemistry of a 54,000-year-old South Pole ice core. The Southern Ocean experiences the largest seasonal difference in sea ice cover in the world, with Antarctica surrounded by 18.5 million-square-kilometers of sea ice in the winter and only 3.1 million-square-kilometers of it in the summer. According to researchers, this seasonal disparity in sea ice has a significant influence on regional and global climate, yet scientists for years knew relatively little about the extent of sea ice variation in the Southern Hemisphere before 1979.