Glacier melting mechanism, artwork. The red arrows show the forward movement of the glacier, with this movement becoming faster as the weight of the leading edge (toe) is offset by the water entering underneath it. This water also lubricates the glacier, with such effects forming a positive feedback loop that leads to rapid calving of a glacier into the sea. Ice loss from glaciers and ice caps is expected to cause an increase in global sea levels. Estimates have concluded that glaciers and ice caps are contributing about 60 percent of the world's ice to the oceans, a rate that has been accelerating in the early 21st century.