National Geographic: Melting Greenland ice could cause oceans to rise by more than a foot (30 centimeters) over the next hundred years. The resulting sea level rise, spurred by global warming, may also happen three times faster than previously predicted. When all other sources of melting ice are also factored in–such as the Antarctic ice sheet and smaller glaciers–the sea level has been predicted to increase by several more feet by 2100, according to previous studies. The new estimates are …