Much of Earth's freshwater is stored as ice, mostly at the poles. The North Pole is
covered by floating pack ice, while the South Pole is covered by the Antarctic ice
sheet. This ice sheet, which covers an area of nearly 14 million square kilometers,
holds about 90% of the freshwater on Earth's surface. During warm months, some
of the polar ice melts, yet global sea levels stay roughly the same. Why does this
occur?