Ice shelves act as a "plug" to slow glaciers running into the sea. So the melting of ice shelves causes glaciers to run into the sea and melt faster. Check out

Ice shelves act as a "plug" to slow glaciers running into the sea. So the melting of ice shelves causes glaciers to run into the sea and melt faster. Check out the BBC documentary "Frozen Planet", episode 7 goes into detail.