Live Talk: Submit Questions on Global Warming

Carbon Footprint
A way of representing the effect human activities have on the climate in terms of the total amount of greenhouse gases produced. This quantity is usually measured in units of carbon dioxide emitted per year.

Net Metering
A method of measuring the energy produced and consumed at a home or business. If a customer generates more than is used, the surplus electricity will run the meter backward. Depending on local rules, the excess may be credited to the customer's account.

Greenhouse Gases
Gases present in the atmosphere that trap heat from the sun and warm the Earth. These include carbon dioxide, methane, nitrous oxide and water vapor. They occur naturally, but are also emitted when fossil fuels are burned.

Carbon Offset
The process of balancing a unit of carbon dioxide emissions with a product that saves or stores an equivalent amount of CO2. Carbon credits are typically bought and sold through a number of online retailers and trading platforms.

Carbon Neutral
Involves calculating your total carbon emissions, reducing them where possible, and balancing your remaining emissions by purchasing carbon offsets. In essence, you neutralize your personal footprint so as not to contribute to global warming.

Kyoto Protocol
An amendment to the international treaty on climate change. Its overall goal is to reduce carbon emissions below 1990 levels by 2012. More than 140 nations ratified the agreement, which went into effect in 2005. The U.S. did not ratify the protocol.

Renewable Energy
A category of energy resources such as wind power that can keep producing energy indefinitely without being depleted. These sources produce few hazardous emissions or pollutants, and have minimal impact on ecosystems.

Cap and Trade
A cap system that sets mandatory limits on pollution. The CO2 emissions allowed under the cap are divided into individual permits. Companies that reduce emissions can sell pollution credits to companies that cannot meet their allowance.