Does manmade CO2 have any detectable fingerprint?

Atmospheric chemistry shows that humans are driving the recent CO2 increase.

A key piece of evidence involves carbon isotope ratios in the atmosphere. Isotopes are different versions of the same element. Carbon comes in three isotopes of different weights and amounts: carbon-12 (98.9% of all carbon), carbon-13 (1.1%) and carbon-14 (trace amounts only).

Photosynthetic plants prefer the lightest isotope, carbon-12, because it is favored in photosynthesis reactions. That means plant tissues have relatively less carbon-13 than carbon-12. Fossil fuels, made of dead plants, also carry that distinct low carbon-13 isotope ratio, as does the CO2 produced by burning them.

Measurements over recent decades show a shift in the isotope ratio of atmospheric CO2, consistent with our burning of large amounts of ancient plant-derived carbon – in other words, fossil fuels. Natural carbon sources, like volcanoes, cannot explain this “fingerprint”.