What is the source of carbon dioxide in fossil fuels?

Answer 1

• The largest source of CO2 emissions globally is the combustion of fossil fuels such as coal, oil and gas in power plants, automobiles, industrial facilities and other sources.
• A number of specialized industrial production processes and product uses such as mineral production, metal production and the use of petroleum-based products can also lead to CO2 emissions.
• Carbon sequestration is the process by which growing trees and plants absorb or remove CO2 from the atmosphere and turn it into biomass (e.g., wood, leaves, etc.). Deforestation, conversely, can lead to significant levels of CO2 emissions in some countries.
• Carbon dioxide can be captured from power plants and industrial facilities before it is released into the atmosphere, and then injected deep underground.

The figure below displays a breakdown of sources of CO2 emissions in the U.S. in 2006. By far the largest source is fossil fuel combustion:

Answer 2

The source of carbon dioxide in fossil fuels comes from the carbon that was originally absorbed by plants through photosynthesis millions of years ago. When these plants died and decomposed, the organic matter was buried and transformed into fossil fuels like coal, oil, and natural gas. When these fuels are burned for energy, the carbon in them combines with oxygen in the air to form carbon dioxide.