Learning Objectives

• Explain why water shortages are increasingly frequent throughout the world.
• Discuss why 1.1 billion people (one-fifth of the people on Earth) do not have access to safe drinking water.

Vocabulary

• drought
• pathogen

Introduction

Humans are facing a worldwide water crisis, according to the United Nations. Many people do not have access to clean water to drink or to wash with. Sometimes there just is not enough water and sometimes the available water is unclean and unhealthy.

World Water Distribution and Supply

Humans use six times as much water today as they did 100 years ago. People living in developed countries use a far greater proportion of the world’s water than people in less developed countries. Water scarcity is a problem now and will become an even larger problem in the future as water sources are reduced or polluted and population grows.

Water Distribution

Water is unevenly distributed around the world. Large portions of the world receive very little water from rainfall or rivers relative to their population. This includes much of northern Africa and central Asia. Over time, there will be less water per person within many river basins as the population grows and global temperatures increase so that some water sources are lost. Over time, many nations, even developed nations, are projected to have less water per person than now.

Global warming will change patterns of rainfall and water distribution. As the Earth warms, regions that currently receive an adequate supply of rain may shift. Regions that rely on snow melt may find that there is less snow and the melt comes earlier and faster in the spring, causing the water to run off and not be available through the dry summers. A change in temperature and precipitation would completely change the types of plants and animals that can live successfully in that region.

Water Shortages

In 1995, about 40% of the world’s population faced water scarcity. Scientists estimate that by the year 2025, nearly half of the world’s people won’t have enough water to meet their daily needs. Nearly one-quarter of the world’s people will have less than 500 m³ of water to use in an entire year. That amount is less water in a year than some people in the United States use in one day.

As water supplies become scarce, conflicts will arise between the individuals or nations that have enough clean water and those that do not (Figure below). Just as with energy resources today, wars may erupt over water.

Droughts occur when a region experiences unusually low precipitation for months or years (Figure below). Periods of drought may create or worsen water shortages.

Human activities can contribute to the frequency and duration of droughts. For example, deforestation keeps trees from returning water to the atmosphere by transpiration; part of the water cycle becomes broken. Because it is difficult to predict when droughts will happen, it is difficult for countries to predict how serious water shortages will be each year.

Scarcity of Safe Drinking Water

The water that comes out of our faucets is safe because it has gone through a series of treatment and purification processes to remove contaminants. Those of us who are fortunate enough to always be able to get clean water from a tap in our home may have trouble imagining life in a country that cannot afford the technology to treat and purify water.

Polluted Water

Many people in the world have no choice but to drink from the same polluted river where sewage is dumped. One-fifth of all people in the world, more than 1.1 billion people, do not have access to safe water for drinking, personal cleanliness, and domestic use (Figure below). Unsafe drinking water carries many pathogens, or infectious organisms, such as bacteria or fungi. Toxic chemicals, radiological hazards, and parasites are also disease-causing agents found in water.

Exponential growth of bacteria is explained in this video giving the viewer a good idea of how a small number of bacteria can cause a major toxic problem. http://www.youtube.com/watch?v=JWfTckls59k

Exponential growth of bacteria is explained in this video giving the viewer a good idea of how a small number of bacteria can cause a major toxic problem (1e – I&E Stand.): http://www.youtube.com/watch?v=JWfTckls59k (16:00).

Waterborne disease caused by unsafe drinking water is the leading cause of death for children under the age of five in many nations and a cause of death and illness for many adults. About 88% of all diseases are caused by drinking unsafe water (Figure below). Throughout the world, more than 14,000 people die every day from waterborne diseases, such as cholera, and many of the world’s hospital beds are occupied by patients suffering from a waterborne disease.

Guinea worm is a serious problem in parts of Africa that is being eradicated. Learn what is being done to decrease the number of people suffering from this parasite in the video below.

http://www.youtube.com/watch?v=u4kQWvUv_Ns

Water Scarcity

Water scarcity can have dire consequences for the people, the economy, and the environment. Without adequate water, crops and livestock dwindle and people go hungry. Industrial, construction, and economic development is halted, causing a nation to sink further into poverty. The risk of regional conflicts over scarce water resources rises. People die from diseases, thirst, or even in war over scarce resources.

In many cases, water disputes add to tensions between countries where differing national interests and withdrawal rights have been in conflict. Some of today’s greatest tensions are happening in places where water is scarce. Water disputes are happening along 260 different river systems that cross national boundaries. Some of these disputes are potentially very serious. International water laws, such as the Helsinki Rules, help interpret water rights among countries.

Lesson Summary

• Water is a renewable resource, but it is not unlimited. Water is not evenly distributed across the globe.
• Water is so valuable that countries have fought each other over water rights throughout history.
• Many people live with water scarcity and many more will do so in the future.
• Underdeveloped countries are rarely able to afford water treatment and purification facilities, although international aid is sometimes available.

Review Questions

1. If most of the Earth is covered with water, how can there be water shortages?

2. Where in the world is there the least amount of water available relative to the human population? Where in North America is there the least amount of water relative to the population?

3. In 2025, where are the water shortages likely to be?

4. Why will there be more regions prone to water shortages in 2025 than there are today?

5. How do human activities contribute to the frequency or duration of droughts?

6. Why are waterborne diseases more common in less developed countries than developed countries?

7. Why does the United Nations describe the current water status today as a crisis?

8. How do droughts affect water supplies?

9. What are the possible consequences of water shortages?

10. Give two reasons why water shortages are happening around the world today.

Points to Consider

• What can we do to help the one-fifth of the people on Earth who do not have access to safe drinking water?
• How can we reduce water shortages because of overuse, overpopulation, and drought?
• Water is so valuable that wars have been fought over it throughout history. Could conserving freshwater now help avoid future wars?