THE WORD resource is derived from the Latin resurgere, meaning to “rise again.” Therefore, a resource can be part of a cyclical process that can change and return over time and space. Resources are those elements that humans have the knowledge and technology to utilize to provide desired goods and services. Resources are subjective, functional, and dynamic. They can be tangible things that create, support, and supply material wealth. Resources, such as beauty, peacefulness, or diversity are considered intangible. Both tangible and intangible resources reflect variations in knowledge, technology, social structures, economic conditions, and political systems.
Humans create particular types of resources: labor, entrepreneurial skills, investment funds, capital assets, cultural adaptations, and technology. Natural resources are substances, organisms, and properties of the physical environment. These resources provide the material wealth that humans are dependent upon. Humans use many natural resources that are also important for other species.
Resources can also be considered renewable or nonrenewable. Renewable resources or flow resources naturally regenerate to provide new supplies within a human life span. These resources can be replenished or replaced continuously and sustainably into the future and faster than they can be used. Renewable resources include sunlight, biological organisms, and biogeochemical cycles that provide essential ecological services and generally will not run out.
For example, biological organisms replace themselves by reproduction; ecological processes are self-renewing. Water is considered a renewable resource. It is part of the hydrologic cycle the moves water in different physical forms and allows for it replenishment over time and space. Humans can harvest the surplus and use it without diminishing future availability.
Nonrenewable resources or stock resources are those things that take millions of years to form and are in a fixed supply in relation to human terms. These resources may be renewed or recycled by geological or ecological processes, but the time scales are so long by human standards that the resource will be gone once present supplies are exhausted. The use of nonrenewable resources is not dictated so much by the absolute amount available but rather is due to the economic and environmental costs required to extract them. The use leads to adaptation through more efficient use, recycling, substitution of one material for another, and better extraction from other sources. Nonrenewable sources include minerals, fossil fuels, or other materials present in fixed amounts in the environment that will eventually run out.
Energy is one resource that is commonly divided into renewable and nonrenewable categories. Renewable energy includes solar, wind, tidal/wave, biomass, hydroelectricity, and geothermal energy. Solar energy is continually supplied to the Earth by the sun. Geothermal energy is continuously created beneath the Earth's surface from the extreme heat contained in liquid rock—magma within the Earth's core. Biomass describes many different fuel types form sources such as trees, agricultural wastes, fuel crops, sewage sludge and manure. Wind is created when the sun heats the Earth's surface unevenly, because of the seasons and cloud cover, causing warmer air to move toward cooler air.
Nonrenewable energy include such things as coal, petroleum, gas, and nuclear energy. Coal is a rock that is a fossil fuel formed over millions of years from decomposing plants. Another fossil fuel is petroleum, or crude oil. It is formed in a similar fashion as coal but is a liquid that became trapped between layers of rocks. Gas is trapped between layers of rock. Nuclear energy is the energy released when atoms are either split or joined together. A mineral called uranium is needed for this process. At each stage of the process, various types of radioactive wastes are produced.
Another way of understanding resource use is by viewing resources as part of a use-renewability continuum. At one extreme are naturally determined, infinitely renewable resources. The amount of these resources is unrelated to current usage levels. Examples include: solar energy, tidal and wind power, and water resources. The other extreme is where utilization exceeds regeneration. The use of the resource is consumptive, and byproducts result in unusable forms of matter and energy. Examples are fossil fuels, plants, animals, fish, forests, and soils. In between these extremes is where resource renewability is dependent on human decisions, where future supply availability is determined by usage rates and investment in artificial regeneration to ensure supply and quality (e.g., air and water quality, or minerals).