Vanishing Arctic sea ice. Dogged weather systems over Greenland. Far-flung surface ice melting on the massive island. 'Blocking-high' pressure systems spawn most of the warming that melts Greenland surface ice, Rutgers study saysThese dramatic trends and global sea-level rise are linked, according to a study coauthored by Jennifer Francis, a research professor in Rutgers University's Department of Marine and Coastal Sciences.During Greenland summers, melting Arctic sea ice favors stronger and more frequent "blocking-high" pressure systems, which spin clockwise, stay largely in place and can block cold, dry Canadian air from reaching the island. The highs tend to enhance the flow of warm, moist air over Greenland, contributing to increased extreme heat events and surface ice melting, according to the study.