Yes, scientists can differentiate between CO2 emitted from human activities and that occurring naturally through carbon cycle processes. This is done by analyzing the carbon isotopes (different forms of carbon) in atmospheric CO2.
Human activity causes carbon dioxide (CO₂) and other greenhouse gases to be emitted into the atmosphere.
Scientists know that the source of CO₂ in the atmosphere is the result of human activity (e.g. burning fossil fuels to produce electricity, transport, and industrial processes). This is because they can analyse the different isotopes of carbon in atmospheric CO₂ to understand their sources.
Measurements of carbon-13 and carbon-14, relative to carbon-12, confirm that the increase in CO₂ concentration since 1800 originates principally from fossil fuel and land clearing emissions.
Electricity production involving the burning of fossil fuels is the predominant contributor to Australia's CO₂ emissions.