Greenhouse gases are benevolent. Where greenhouse gases become a concern is when there is too much of them to trap infrared energy resulting in heat.
Water mitigates the climate that greenhouse gases create. The more greenhouse gases in the troposphere of Earth, the greater the need for mitigation of the heat by water vapor.
Of the phases of water, it is vapor that is the last phase to accept heat from the troposphere. That has been a good thing. Water vapor not only exists because of the Earth's infrared heat, it also acts to move water around to provide rain and seasons. Under a normal troposphere seasonal changes are also mitigate to allow a wide spread distribution of that heat rather than a concentrated amount of heat from solar rays. It is a matter of surface area. Water vapor accepts Earth's heat and then builds into clouds that travel around the Earth to bring rain and shade.
Today, everyone age of 15 years old remembers less turbulence and a more benevolent climate. Today, water vapor continues to receive heat and turns it into physical wind and rain, etc., with far more ferocity.
I believe the best concept to understand this from a scientific view is "The Mechanical Equivalent of Heat." (click here) It is the relationship of heat and work. It has a formula of J (joule) = W (work) / Q (heat). The equation works in both directions, hence the equal sign. It is an equation within theromodynamics.
The heat is the ever growing greenhouse gas infrared heat. The work is that of the water vapor cloud system that mitigates the heat. And the joule is the understood energy used in the mitigation in the climate.
In a climate model which reflects the increasing heat and water vapor the joule would be an indication of how different the climate is compared to 150 years ago. Water vapor due to it's properties effects change (mitigation of heat) in motion.
Example: How many joules are produced by a tornado? Tornadoes result from heat mitigated by water vapor or lack there of. Hurricanes are the same way. Due to the dynamics of Earth, hurricanes have a vector.
But, that is the relationship of water to global warming. It mitigates the heat as it has within a far more 'normal' troposphere, but, with greater indications of energy due to higher infrared heat trapped by ever increasing greenhouse gases the result in no longer benevolent.