Reuters: An ice bridge made of frozen Antarctic water erected at U.N. headquarters on Monday is expected to melt within a week to dramatize the dangers of melting glaciers. Norwegian artist Vebjorn Sand brought the fresh water to New York to fashion a temporary bridge based on a Leonardo da Vinci design. It replicates another span he built on a glacier in Antarctica a year ago which he hopes will never melt. “Our future lays underneath that ice glacier. So to erect it on that …