The corruption of science by wealthy and corporate interests, and the spinning of propaganda by governments has made many people entirely distrustful of any science. The oil and gas industries/owners have bought themselves many years of profits by sowing doubts just like yours, and I'm sorry to see them be as successful as they are.
In the case of rising CO2 levels, among the scientists who work in this field, there is a super-majority beyond which there is no higher level possible with humans involved. I know how difficult this is since I worked in a military research lab with about 30 PhDs . Our larger organization had hundreds of PHD's. Getting a small group of PhDs to agree on anything was virtually impossible.
When you think that you know about a field of science in which people have spent their entire academic lives working in, this is likely the result of the Dunning-Kruger effect which has been extremely well confirmed as an inherent human trait. You often see it in PhD's ruminating about fields outside there own field. We are all susceptible.
I don't trust governments or scientists in general, and have a distrust of my own brain damaged intellect. In this case, having looked more closely at the CO2 data and the subsequent ocean temperature and arctic ice loss confirmations by NASA, it's pretty damned obvious the scientific consensus is warranted and we're in serious trouble. Scientists get ridiculed and attacked within their own ranks for making exaggerated statements- so they intentionally understate and avoid grandstanding. Some have expressed the situation in terms like "possible extinction event". They just don't know what will happen to the worlds ecosystem balance as CO2 levels rise above those estimated for our current epoch, and they are very concerned. They are concerned that by doing nothing, we may bring about our extinction. While I'm not a huge fan of humans, I don't know of any better sentient beings, and I think we should try to use the best science available to guide us.