Causes of Environmental Changes

A number of interconnected factors contributed to the environmental changes that have taken place since 1900.

Population Growth In 1900, the world population was 1.6 billion. By 1950 it had risen to 2.55 billion, and by 2000 the population was 6.12 billion. All of the billions more people that lived on the planet since 1900 needed to be fed. Growing populations led to a demand for more croplands. This increase in land used for agricultural purposes resulted in deforestation, soil erosion, and smaller habitats for many species of plants and animals.

Growing populations affected not only land resources but also water resources. Overfishing in the oceans has led to the near disappearance of cod. Although fresh water is a renewable resource, growing populations consume increasing amounts of it.

Urbanization Another cause of environmental change is the increasing size and number of cities. By some estimates, by 2025, 5.1 billion people will live in cities, which will pressure those who grow food to use intensive farming methods that deplete the soil and cause erosion or to clear more forests for agricultural use. City dwellers also produce vast amounts of waste, some of which pollutes the water they depend on.

Globalization and Industrialization The global reach of industrialization has also affected the environment. As industry spread to developing countries, energy and other natural resources used in manufacturing were in demand, drawing further on the reserves of resources. Workers in industry in these developing countries are creating a new middle class that increases the market for such products as cars that require metals and other resources and that also contribute to pollution.