Carbon dioxide in Earth's atmosphere Atmospheric O levels are decreasing in Earth's atmosphere as it reacts with the carbon in fossil fuels to form . Burning fossil fuels such as coal, petroleum, and natural gas is the leading cause of increased anthropogenic ; deforestation is the second major cause. In 2010, 9.14 gigatonnes of carbon (GtC, equivalent to 33.5 gigatonnes of or about 4.3 ppm in Earth's atmosphere) were released from fossil fuels and cement production worldwide, compared to 6.15 GtC in 1990. In addition, land use change contributed 0.87 GtC in 2010, compared to 1.45 GtC in 1990. In 1997, human-caused Indonesian peat fires
Natural gas vehicle Natural gas vehicle A natural gas vehicle (NGV) is an alternative fuel vehicle that uses compressed natural gas (CNG) or liquefied natural gas (LNG). Natural gas vehicles should not be confused with vehicles powered by LPG (mainly propane), which is a fuel with a fundamentally different composition. In a natural gas powered vehicle, energy is released by combustion of essentially Methane gas () fuel with Oxygen () from the air to carbon dioxide () and water vapor () in an internal combustion engine. Methane is the cleanest burning hydrocarbon and many contaminants present in natural gas are removed at source.