Scienceline: A melting ice sheet may cause sea levels to rise unevenly around the globe, recent research reveals. By Allison Bond, posted April 6th, 2009. Share: These icons link to social bookmarking sites where readers can share and discover new web pages. The ocean bordering North American coastal cities like New York, Washington, D.C. and Los Angeles may rise by more than 20 feet if the West Antarctic ice sheet melts due to global warming, new research suggests. That figure is 25 …