News - September 5, 2008 A Deep Thaw: How Much Will Vanishing Glaciers Raise Sea Levels? Some say high, some say low, some say fast, some say slow By David Biello GLACIAL SPEED: Greenland may get much of the scientific attention but it is smaller glaciers such as the Columbia Glacier in Alaska pictured here that are already contributing to sea level rise--and will continue to do so in future. Greenland, the world's largest island, holds enough ice to raise global sea levels by 23 feet (seven meters). Add the ice sheets of Antarctica and the oceans would deepen more...