Not gonna lie. I've spent a few minutes trying to find good numbers and google isn't as awesome as it usually is.

The actual amounts of ghg produced by natural sources is hard to find.

The treatment of water vapor in the atmosphere and the feedback loop of
warmer air -> holds more moisture -> holds more heat -> is warmer air
is poorly understood, 'cause more moisture also leads to more clouds, which reflect incoming light before it warms the moist air below them.

Not sure the long term trends on increased water vapor, and water vapor content in the atmosphere is (AFAICT) not something you can determine geologically or radiologically... so a huge ??? in past trends.

None of which is contrary to the fact that humans are definitely emitting greenhouse gasses, which are so named due to their contributions to global warming. It's just that the long term effects are not well modeled.