We do not know if CO2 is the cause of global warming
Why does CO2 drive global warming when there is only 0.04% of it in the atmosphere? And why isn’t water vapor the major driving factor? [...] Both water vapor and CO2 are responsible for global warming, and once we increase the CO2 in the atmosphere, the oceans warm up, which inevitably triggers an increase in water vapor. But while we have no way to control water vapor, we can control CO2. And because we are increasing the amount of CO2 in the atmosphere by continuing to burn fossil fuels, even in relatively small amounts compared to the entire mass of the atmosphere, we are disturbing the entire heat balance of the planet. For more information on how carbon dioxide traps heat, why water vapor isn’t the culprit, and answers to several other interesting questions, check out this post: How Exactly Does Carbon Dioxide Cause Global Warming?