It's certainly the case that CO2 is not the only greenhouse gas. But speaking as a scientist I'm afraid there really is no doubt that human activity is changing the climate.
As for those who are trying to persuade people otherwise, did you ever consider their vested interests, or those of the people who pay them? The story that scientists will make up something like this to get grants, and that reviewers will turn a blind eye to this because of, well, whatever (they never seem to worry about coming up with a story to explain that), is a classic smear.