When petroleum products such as gasoline are burned for energy, they release toxic gases and high amounts of carbon dioxide, a greenhouse gas. Carbon helps regulate the Earth’s atmospheric temperature, and adding to the natural balance by burning fossil fuels adversely affects our climate. There are huge quantities of petroleum found under Earth’s surface and in tar pits that bubble to the surface. Petroleum even exists far below the deepest wells that are developed to extract it. However, petroleum, like coal and natural gas, is a non-renewable source of energy. It took millions of years for it to form, and when it is extracted and consumed, there is no way for us to replace it.