Most climate scientists accept that carbon dioxide in the atmosphere has some warming effect on Earth’s climate, but undisputed science shows that its direct effect is tiny and declines dramatically as carbon dioxide levels rise.
The climate models produce scary warming forecasts by assuming “positive feedbacks”. This is the basis of their claims that man’s production of this harmless gas-of-life is pushing Earth towards an irreversible temperature tipping point.
Their main feedback assumption, expressed simply, goes like this: more carbon dioxide produces surface warming, which causes more evaporation from the oceans, which increases water vapour in the atmosphere, which increases greenhouse warming, which causes more evaporation, and so on, and on.