Humans and wildlife face water woes.

• Author: Krchnak, Karin M.
• Position: Ecology

WE DO NOT OFTEN THINK of water scarcity in the U.S. Water is readily available in bottles at our local grocery store. It appears plentiful in the lakes and rivers near our homes. We consider drought an occasional summertime nuisance that is easily remedied by not watering our lawns or washing our cars. A growing body of science warns, however, that the availability of plentiful, clean water is unlikely to be something we will take for granted in the future. A skyrocketing human population is draining the Earth's finite freshwater supply at an alarming rate. We are already catching a glimpse of the consequences for people, wildlife, and the environment on which they depend. With population projected to continue a steady climb, wisely managing Earth's freshwater is crucial to protecting humanity and wildlife that rely on the world's water in the future.

There is no more water on Earth now than there was 2,000 years ago. The world population sharing the planet's finite freshwater supply then was about 200,000,000. Yet, more than 6,000,000,000 people depend on that same finite freshwater supply today. If current rates continue, global population could reach 13,000,000,000 by the middle of this century. While we cannot be certain how many people the Earth can sustain, we know that the human population that depends on its finite freshwater resources has tripled in the last century. It continues to grow by almost 80,000,000 per year. In addition to drinking water, more people bring increased demand for water to support industrialization, agricultural development, urbanization, and sprawl.

Currently, the human population consumes approximately 54% of all the accessible freshwater contained in rivers, lakes, and underground aquifers. By 2025, population growth alone could push this figure to 70%. Caught between limited--and increasingly polluted--water supplies and rapidly rising demand, many countries face extremely difficult choices. The World Bank warns that a lack of freshwater is likely to be one of the major factors limiting economic development in the decades to come.

The world's freshwater crisis is underscored by the lack of access to clean drinking water and proper sanitation facilities. Approximately 1,500,000,000 people do not have access to potable water, and 3,000,000,000, half the global population, lack sanitation facilities, such as a sanitary latrine, covered wastewater drain, or flush toilet. The World Health Organization estimates that, every year, about 2,300,000,000 people suffer from diseases linked to polluted water.

With more than 90% of the world's population growth occurring in the developing world, it is projected that the number of people living under conditions of water scarcity will increase. This is stretching...