The Thwaites Glacier in West Antarctica is the world's largest and widest glacier. The massive ice sheet stretches 80 miles (129 km) across, roughly the size of Florida. The glacier loses about 50 billion tons of ice annually and already accounts for about 4 percent of the planet's current sea level rise. If it were to melt completely, it could raise global sea levels by about two feet (61 cm). This would displace millions of people in coastal communities worldwide. It is no wonder the ice mass has been nicknamed "Doomsday Glacier."