> My suspicion is that water vapor from air travel is by far the biggest contributor.

Have you calculated the water vapor generated from air travel, and compared that to the water vapor already generated by the water cycle? (just normal evaporation from lakes/rivers/oceans/plants)

Even as back-of-napkin math, this should be a pretty easy sanity check.

I think you're off by a few orders of magnitude here, but I also don't want to discourage you from adopting a "check for yourself" mindset.

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phkahler 2 hours ago | parent [-]

>> Have you calculated the water vapor generated from air travel, and compared that to the water vapor already generated by the water cycle?

I've SEEN the effects with my own eyes. You can also see contrails seeding cloud formation on some days. Then there's the fact that these extra clouds are formed and dissipate on a 24 hour cycle, so part of the day they let in sunlight and part of the night they trap heat. These effects are significant and there is little research on the bigger picture effects of this (that I've seen).

	▲	gzread 18 minutes ago \| parent \| next [-]
		How significant? Give me a number. What percentage of all the clouds in a day come from planes?
	▲	kibibu 2 hours ago \| parent \| prev [-]
		Clouds reflect radiant heat back into space. Contrary to your claim, "global dimming" was a very active research space for a long time, and in fact the water vapour and other airborne pollutants likely masked the impact of global warming.