ABSTRACT
Water is essential to life. Every living thing on Earth requires freshwater to survive, yet access to freshwater is not a given. More than 96% of the Earth’s water is in the form of seawater. Freshwater resources in the form of precipitation and water in lakes, rivers, streams, and aquifers make up the remaining 4%.* According to the United Nations, almost one-fifth of the world’s population faces water scarcity today.† As the world’s population increases (Figure 14.1) and the climate warms (Figure 14.2), water scarcity will pose an even greater challenge.
