Final answer:
Glaciers presently cover about 10% of the surface of the continents. Antarctica alone accounts for approximately 70% of the Earth's fresh water trapped in its massive ice sheet. Sea levels would rise significantly if all the ice present in glaciers were to melt.
Step-by-step explanation:
At present, glaciers cover about 10% of the surface of the continents. This encompasses massive ice sheets in regions like Antarctica and Greenland. For perspective, about 98% of Antarctica is smothered by an ice sheet that is, on average, up to a mile deep, representing roughly 70% of the Earth's fresh water. Should this ice melt, global sea levels would rise substantially, dramatically altering the Earth's coastlines and affecting low-lying regions.
Furthermore, during the most recent glaciation period, ice sheets extended far beyond their current range, covering substantial portions of the Northern Hemisphere and reducing Earth's sea levels considerably compared to today.