23.1 Fresh Water

How would you describe Earth's surface? Would you mention mountains and valleys, or cities and farms? Most people would describe the landscape. But if you could look at Earth from space, you would see that most of its surface—about 71 percent— is covered with water. For this reason, Earth is sometimes called the “water planet.” For billions of years, the presence of water has shaped the geology and biology of Earth's surface.

The temperature range on Earth allows water to occur in three states: liquid, solid, and gas. As shown in Figure 1, most of Earth's water is the salt water found in the oceans. Only about three percent of Earth's water is fresh. Most of this fresh water occurs as ice and snow in Earth's high mountains and polar regions. Most of Earth's liquid fresh water is in the form of groundwater, the water found underground within cracks and between particles of rock and soil. Smaller amounts of fresh water are found in lakes and streams and as water vapor or clouds in the atmosphere.

Figure 1 Earth is the only planet with liquid water at its surface. Using Graphs What percentage of Earth's water can be found in glaciers?

Table of Contents