In a Swedish Facebook group for "climate change skeptics" Erik Larsen has shared his calculation of how big part of temperature change can be attributed to human emissions of carbon dioxide. His reasoning goes as follows:
- Temperature has raised by 1 °C since 1850.
- Carbon dioxide has raised by 30%.
- Carbon dioxide only constitute 4% of the greenhouse gases (the main part consists of water vapor).
- Carbon dioxide is only 1/4 as efficient as water vapor per molecule as a greenhouse gas.
From this he concludes that the temperature raise from carbon dioxide is only 1 °C × 0.30 × 0.04 × 1/4 = 0.003 °C.
I have tried to explain (in Swedish) that this calculation is not correct, but of course he refuses to accept that and writes that my objections are not logical. Today I wrote that it's lucky for him that his calculation is not peer-reviewed and suggested that I could share it in a physics and/or mathematics group for review. He complied. So here it is.
What do you think of his calculation?