Is water vapor the main villain in global warming?

The short answer to this question is yes. Which is why paid industry hacks use this fact to denigrate what genuine climate scientists say about global warming. But, it is an entirely misleading assertion as this somewhat technical post on RealClimate explains. In a nutshell: Increased water vapor in the atmosphere is largely the result of man-made releases of carbon dioxide and methane, two well-understood greenhouse gasses. As the atmosphere warms due to our releases of greenhouse gasses, it absorbs more water vapor. In the language of climate scientists, this is feedback not a forcing. It wouldn't occur but for our actions.

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