The link will take you to an interesting but technical article. You have to sign in to read it. It says for unregistered users "sign up for free now".

If you don't want to bother, some interesting items are that water vapor is only 0.25% of atmosphere. CO2 is 400 parts per million which would be 0.04% of atmosphere. Climate change deniers used to like to put the small percentage of CO2 as making it impossible for CO2 to affect climate. I suppose because water vapor is only 0.25% it does nothing?

Also of interest is the feedback between CO2 and water vapor. Warmer air holds more water vapor (scientific fact: it's just physics). The article says that doubling CO2 would increase earth's temperature 1 deg C if there was no water vapor. But there is water vapor and the feedback makes a much larger temperature increase.

To paraphrase the Republican former Governor of Utah Huntsman, I prefer to believe things in this article, written by experts, then believe what some radio personality or senator from Oklahoma (etc).

Chris

• Physics Today: water