The combustion of fossil fuels always produces heat, sometimes as a primary, desired product, and sometimes as a secondary, less-desired by-product. For example, families burn coal, oil, natural gas, or some other fuel to heat their homes. In such cases, the production of heat is the object of burning a fuel. Heat is also produced when fossil fuels are burned to generate electricity. In this case, heat is a byproduct, not the main reason that fuels are burned.

Heat is produced in a number of other common processes. For example, electricity is also generated in nuclear power plants, where no combustion occurs. The decay of organic matter in landfills also releases heat to the atmosphere.

It is clear, therefore, that a vast array of human activities result in the release of heat to the environment. As those activities increase in number and extent, so does the...