How can a colourless, odourless gas like CO2 that only makes up 0.04 percent of the atmosphere (or 427 parts per million, as of 2026) have an effect on global temperatures?
Fact:
This argument sounds plausible, however is it completely fallacious, as the quantity of a substance is not the only factor determining its impact. For example, Chlorofluorocarbons (CFCs) and Hydrochlorofluorocarbons (HCFCs) make up just 1,190 parts per trillion of the atmosphere (or just over one part per billion), yet threatened to destroy the ozone layer (with extremely deleterious repercussions for life on Earth). Similarly, just 35 parts per billion of arsenic in drinking water is hazardous to health, and 800 parts per million of alcohol in the bloodstream is enough to render a person intoxicated. Finally, the painkiller ibuprofen works at just 3 parts per million. So, of course CO2 can have an impact at just 427 parts per million.