but water vapour takes many forms from humidity to clouds to rain to oceans.
humidity absorbs and retains heat, so it adds warming effect.
clouds form and blocks heat from penetrating the surface so provides insulation. so clouds also trap warmth beneath. IR is unaffected by high, thinner clouds but can be blocked by much thicker lower clouds: https://earthobservatory.nasa.gov/features/Clouds/clouds4.php
rain loses heat through natural cooling (heat loss). rain also captures GHGs and adds the compounds to oceans and land.
oceans then include GHG molecules and acidifies ground water, lakes and oceans. surface water absorbs heat energy through convection between the liquids and so the average temperature of oceans increases.
warmer waters evaporate more readily, thereby increasing the rate of convection and the rate of the water cycle... and also radiate heat energy back into the atmosphere.
lastly in the water cycle is ice. this is an important part as it reflects light and heat energy. but ice also melts with higher atmospheric temperature. so like other parts of the cycle, ice serves a dual role. but the less ice on the surface of the planet, the faster the rate of warming.
so yeh Q.... water plays an important part of the GW cycle but has many different stages.
imo the biggest threat to species comes from ocean acidification and the melting of ice.
its been fascinating watching the debate here. round and round and round we go.... where we stop no bugger knows.
