Water vapor, a greenhouse gas fluctuates much more than 0.008% (1/125th of 1%).
How much effect does water vapor have compared to CO2? And has it increased, accounting for the increase in global temperatures?
Does water vapor reflect energy back into space, acting sometimes as a global cooler?
If an increase in water vapor increases global warming, does the warming generate more water vapor, yielding a positive feedback loop? If so, what counters the loop?
How many degrees would the earth’s temperature drop if all the CO2 disappeared from the atmosphere? How many degrees increase if CO2 doubled, trebled, or quadrupled?
I don’t know the answers.