West of McMurdo the ice is melting and breaking away. The jet stream associated with the circumpolar current dips low bringing warm moist air in from the mid-latitudes, this has been shown to increase ice mass at sea. Contrarily, east of McMurdo and at Ross Island, ice cover is growing. The jet stream dips upwards bringing the cold air to the north. Globally there is more sublimation and melt vs. accumulation of ice.