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
History of the petroleum industry in Canada (natural gas) stacks. One chemical result of burning hydrogen sulphide emissions was sulfur dioxide, another toxic gas. Since hydrogen sulphide is heavier than air, it settled to the ground, dispersed enough to be less than lethal. Hydrogen sulphide was always in the air in small concentrations. Turner Valley had a rotten egg odour on most days. As Alberta became an ever-larger oil producer after the Leduc discovery, the Conservation Board acted to prevent any repetition of the natural gas waste so common in Turner Valley. The board developed a broad conservation policy for natural gas. It prohibited producing natural gas from an