[Shadow6363]

Water is a greenhouse gas?

[credit_guy]

Not only water (vapor) is a greenhouse gas, it's by far the most important. Per wikipedia, its contribution to the greenhouse effect is 36-72%, while the next contribution, of CO2, is 9-26%.

https://en.m.wikipedia.org/wiki/Greenhouse_gas

[T-A]

Yep: https://www.ncdc.noaa.gov/monitoring-references/faq/greenhou...