People and Planet - Water's Next

Wars have been fought over oil, but many people predict that the next war will be fought over water. Certainly, water is becoming scarcer.

Water Distribution
Water is unevenly distributed around the world. Large portions of the world, such as much of northern Africa, receive very little water relative to their population (Figure below). The map shows the relationship between water supply and population by river basin.

Blue means there is a lot of river water for each person who lives in the river basin. Salmon pink means there is very little river water for each person who lives in the river basin. 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. In 2025, many nations, even developed nations, are projected to have less water per person than now (Figure below).


The same map but projected into 2025.

Water Shortages
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. 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.


Water supply compared to population.


Extended periods with lower than
normal rainfall cause droughts.
DROUGHTS
Droughts occur when a region experiences unusually low precipitation for months or years (Figure right). 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.

EFFECT OF CHANGING CLIMATE
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 snowmelt 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 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. Industry, 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.

By 2025, many nations will face water scarcity. For the nations in red, there will simply not be enough fresh water; the nations in brown may not be able to afford to supply their citizens with fresh water.

Source: Open Education Group Textbooks - Earth Science 

Water is one of Earth’s resources.  It is distributed unevenly across the globe.   Like other of Earth’s resources, such as fertile soil and clean air, human populations depend on water for sustenance.   Changing conditions over time, such as global warming, clear cutting, dam building, pollution, and increasing human populations, have affected Earth’s water resources. 

For information about Utah’s own resources are distributed check out this website.