More than 7 billion people share the Earth and its natural resources. The U.S. Census Bureau projects that the global population will increase to 8 billion by 2025, and as the population increases, the demand for natural resources will increase as well. Although some regions are more populated than others, overpopulation has repercussions for the environment and everyone who shares it.
The world's population increased by more than 4 billion people during the 20th century. Although population growth rates are declining in several parts of the world, the population continues to grow and tax natural resources. In areas of tremendous population growth, fossil fuels, timber, water and arable land can become scarce because of overconsumption and degradation. Resource scarcity has several consequences, including the forced migration of people. In contrast, resource scarcity often leads to technological innovations that find more efficient uses for resources.
Food, fuel and energy prices rise when natural resources become scarce. A growing population means growing demand for resources. If demand rises too quickly, resource scarcity results and causes prices to rise for several reasons. Nonrenewable resources, including fossil fuels, cannot be replaced, so prices increase when supply dwindles. Even renewable resources, including timber, can increase in price if they need to be shipped long distances to reach areas where natural resources have been depleted.
People's consumption of energy for transportation, heat, food production and other activities generates air, land and water pollution. More people means more pollution, which can exacerbate the depletion of natural resources. For example, when fossil fuels are burned to generate power, carbon dioxide is released. This greenhouse gas traps heat in the atmosphere and contributes to climate change, a process that affects weather patterns, water resources and the survival of animals and plants many depend on as food sources. Several industrial processes release harmful chemicals into the air and water as well.
In some areas of rapid population growth, such as sub-Saharan Africa, access to clean water is not guaranteed. When infrastructure development cannot keep up with population growth, water shortages and sanitation issues can occur. Almost 1 billion people lack access to clean water, and more than twice that many do not have toilets. (see reference 6) Fecal contamination is a major cause of disease; water-related sickness kills a child every 21 seconds. People in impoverished, densely populated areas often spend more money and time accessing clean water than people living in developed areas.