The Sheldon Glacier with Mount Barre in the background, is seen from Ryder Bay near Rothera Research Station, Adelaide Island, Antarctica, in this NASA/British Antarctic Survey handout photo. Sea levels could rise by 2.3 metres for each degree Celsius that global temperatures increase and they will remain high for centuries to come, according to a new study by Potsdam Institute for Climate Impact Research, released on July 15, 2013. [Photo/Agencies]