A resource is any physical material that constitutes part of Earth and which people need and value. There are three basic resources—land, water, and air—that are essential to human survival. However, any other natural material also becomes a resource if and when it becomes valuable to humans. The geographically informed person must develop an understanding of this concept and of the changes in the spatial distribution, quantity, and quality of resources on Earth’s surface.

Those changes occur because a resource is a cultural concept, with the value attached to any given resource varying from culture to culture and period to period. Value can be expressed in economic or monetary terms, in legal terms (as in the Clean Air Act), in terms of risk assessment, or in terms of ethics (the responsibility to preserve our National Parks for future generations). The value of a resource depends on human needs and the technology available for its extraction and use. Rock oil seeping from rocks in northwestern Pennsylvania was of only minor value as a medicine until a technology was developed in the mid-nineteenth century that enabled it to be refined into a lamp illuminant. Some resources that were once valuable are no longer important. For example, it was the availability of pine tar and tall timber—strategic materials valued by the English navy—that in the seventeenth century helped spur settlement in northern New England, but that region now uses its vegetative cover (and natural beauty) as a different type of resource—for recreation and tourism. Resources, therefore, are the result of people seeing a need and perceiving an opportunity to meet that need.

The quantity and quality of a resource is determined by whether it is a renewable, non-renewable, or a flow resource. Renewable resources, such as plants and animals, can replenish themselves after they have been used if their physical environment has not been destroyed. If trees are harvested carefully, a new forest will grow to replace the one that was cut. If animals eat grass in a pasture to a certain level, grass will grow again and provide food for animals in the future, as long as the carrying capacity of the land is not exceeded by the pressure of too many animals. Nonrenewable resources, such as minerals and fossil fuels (coal, oil, and natural gas), can be extracted and used only once. Flow resources, such as water, wind, and sunlight, are neither renewable nor nonrenewable because they must be used as, when, and where they occur. The energy in a river can be used to generate electricity, which can be transmitted over great distances. However, that energy must be captured by turbines as the water flows past or it will be lost.

The location of resources influences the distribution of people and their activities on Earth. People live where they can earn a living. Human migration and settlement are linked to the availability of resources, ranging from fertile soils and supplies of freshwater to deposits of metals or pools of natural gas. The patterns of population distribution that result from the relationship between resources and employment change as needs and technologies change. In Colorado, for example, abandoned mining towns reflect the exhaustion of nonrenewable resources (silver and lead deposits), whereas ski resorts reflect the exploitation of renewable resources (snow and scenery).

Technology changes the ways in which humans appraise resources, and it may modify economic systems and population distributions. Changes in technology bring into play new ranges of resources from Earth’s stock. Since the industrial revolution, for example, technology has shifted from waterpower to coal-generated stream to petroleum-powered engines, and different resources and their source locations have become important. The population of the Ruhr Valley in Germany, for example, grew rapidly in response to the new importance of coal and minerals in industrial ventures. Similarly, each innovation in the manufacture of steel brought a new resource to prominence in the United States, and resulted in locational shifts in steel production and population growth.

Demands for resources vary spatially. More resources are used by economically developed countries than by developing countries. For example, the United States uses petroleum at a rate that is five times the world average. As countries develop economically, their demand for resources increases faster than their population grows. The wealth that accompanies economic development enables people to consume more. The consumption of a resource does not necessarily occur where the resource is produced or where the largest reserves of the resource are located. Most of the petroleum produced in Southwest Asia, for example, is consumed in the United States, Europe, and Japan.

Sometimes, users of resources feel insecure when they have to depend on other places to supply them with materials that are so important to their economy and standard of living. This feeling of insecurity can become especially strong if two interdependent countries do not have good political relations, share the same values, or understand each other. In some situations, conflict over resources breaks out into warfare. One factor in Japan’s involvement in World War II, for example, was that Japan lacked petroleum resources of its own and coveted oil fields elsewhere in Asia, especially after the United States threatened to cut off its petroleum exports to Japan.

Conflicts over resources are likely to increase as demand increases. Globally, the increase in demand tends to keep pace with the increase in population. More people on Earth means more need for fertilizers, building materials, food, energy, and everything else produced from resources. Accordingly, if the people of the world are to coexist, Earth’s resources must be managed to guarantee adequate supplies for everyone. That means reserves of renewable resources need to be sustained at a productive level, new reserves of nonrenewable resources need to be found and exploited, new applications for flow resources need to be developed, and whenever possible, cost—effective substitutes—especially for non—renewable resources—need to be developed.

It is essential that students have a solid grasp of the different kinds of resources, of the ways in which humans value and use (and compete over) resources, and of the distribution of resources across Earth’s surface.