Are global warming scientists interested in the roles of water vapor, undersea volcanoes & sunspot energy?

You have to think about in terms of the Titanic. It only took that last gallon of seawater to sink the ship. So the question is, how close are we to a tipping point? Water vapor is the result evaporation, and evaporation has to do with the degree of heat energy of the overlying air m. Heat physics state that the warmer the air m the more water will evaporate into that air m. Even a fraction of a degree 'warmer' over the surface of an ocean is a lot of water vapor. While it may be counter intuitive the amount of evaporated water actually is way out of proportion to the heat energy that causes that evaporation. Likewise there a maximum amount of CO2 and methane that when reached actually does reduce the outgoing infrared radiation to the point where more heat is retained then is allowed to escape into outer space. That point was reached in 1990 when CO2 concentration reached 350ppm. Currently its at 386ppm and 400ppm is where the last gallon of water rushes in and sinks the ship...not immediately, but over a relatively short period of time considerable climate change WILL happen. As we add 12 to 15ppm of CO2 every decade, that's something to think about. Volcanoes are a factor of course, but that amount has already been factored into the equation....industrial CO2 is by far the more culpable. The sun's energy, either at solar max or solar minimum still has to be re-radiated, and the greenhouse effect is the key to that re-radiation...if it's not, things heat up! Methane and CO2ppm are 'small' as you stated, but their role is large...just like that last gallon of water sloshing into the Titanic's hull. Bummer for us!