in the arctic, the area of ocean covered by sea ice increases over winter from a minimum in september to a maximum in march or sometimes february, before melting over the summer. in the antarctic, where the seasons are reversed, the annual minimum is typically in february and the annual maximum in september or october, and the presence of sea ice abutting the calving fronts of ice shelves has been shown to influence glacier flow and potentially the stability of the antarctic ice sheet.