Precipitation that has become acidic (low pH) due to the emission of sulfur oxides from fossil fuel-burning power plants. Source: U.S. Department of Energy / Office of Energy Efficiency and Renewable Energy

Fuels derived from resources other than petroleum. Some are produced domestically, reducing dependence on foreign oil, and some are derived from renewable sources. Often, they produce less pollution than gasoline or diesel. Source: U.S. Department of Energy / Office of Energy Efficiency and Renewable Energy

Alternative fuel made from virgin vegetable oil or used vegetable oil. Some animal fats like beef tallow and fish oil can be used to make biodiesel fuel. May be blended with conventional diesel to get different blends such as B2 (2 percent biodiesel and 98 percent conventional diesel) or B20 (20 percent biodiesel) or it can be used as 100 percent b [..]

The variability among organisms on Earth and within an ecosystem. Maintaining biodiversity is necessary to preserve the health and survival of an ecosystem.

Bioenergy is renewable energy made from any organic material from plants or animals. Sources of bioenergy are called "biomass," and include agricultural and forestry residues, municipal solid wastes, industrial wastes, and terrestrial and aquatic crops grown solely for energy purposes. Source: U.S. Department of Energy.

The standard measure of heat energy. It takes one Btu to raise the temperature of one pound of water by one degree Fahrenheit at sea level.

Large-scale emitter's of CO2 and other greenhouse gas emissions will have a limit ("cap") on the amount of emisisons they are permitted. Emitters who reduce their emissions below their allowed limits can sell ('trade") their extra emitting capacity to the less efficient emitters.

The total amount of carbon dioxide and other greenhouse gases emitted over the full lifecycle of a product or service, expressed as grams of CO2 equivalents.

The act of mitigating greenhouse gas emissions through emissions trading. Individuals or companies voluntarily purchase credits for another party to offset their actions. The goal of carbon offsets is to attain an overall effect of carbon neutrality.

Any significant change in measures of climate (such as temperature, precipitation or wind) lasting for an extended period (decades or longer). Climate change may result from: Natural factors, such as changes in the sun's intensity or slow changes in the Earth's orbit around the sun