Source of data and further research: The Basics: Isotopic Fingerprints | NOAA
You’ve seen that burning fossil fuels, such as in a car, can produce a large concentration of carbon dioxide. But how can we determine the source of carbon dioxide in the atmosphere? Is it from human sources, like the burning of fossil fuels, or natural ones, like the ocean? The answer lies in isotopes. Isotopes are atoms of the same element that have different masses, due to different numbers of neutrons. A carbon dioxide molecule can have one of three different carbon isotopes: Carbon-12, Carbon-13 or Carbon-14. Fossil fuels, like gasoline, coal and natural gas, do not contain Carbon-14. Scientists measure the concentration of the different carbon isotopes in the atmosphere and have determined that the increase in carbon dioxide is due mainly to the burning of fossil fuels.