Carbon dioxide in Earth's atmosphere atmosphere, oceans, soil, rocks, and volcanism. Both carbon cycles are intrinsically interconnected and atmospheric gaseous carbon dioxide facilitates the carbon cycle. Natural sources of atmospheric carbon dioxide include volcanic outgassing, the combustion of organic matter, wildfires and the respiration processes of living aerobic organisms. Man-made sources of carbon dioxide include the burning of fossil fuels for heating, power generation and transport, as well as some industrial processes such as cement making. It is also produced by various microorganisms from fermentation and cellular respiration. Plants, algae and cyanobacteria convert carbon dioxide to carbohydrates by a process called photosynthesis. They gain the
Coal maximum. As of 2018 global peak coal consumption is predicted to occur by the early 2020s at the latest. Coal-fired generation puts out about twice the amount of carbon dioxide—around a tonne for every megawatt hour generated—than electricity generated by burning natural gas at 500 kg of greenhouse gas per megawatt hour. In addition to generating electricity, natural gas is also popular in some countries for heating and as an automotive fuel. The use of coal in the United Kingdom declined as a result of the development of North Sea oil and the subsequent dash for gas during the 1990s.