You're confusing science with something else, I think. Going back to the parent, the skeptics need to disprove one of several reliably tested things, that 1) CO2 is a greenhouse gas, 2) atmospheric CO2 levels are increasing, and 3) Man is dumping a lot of CO2 into the atmosphere. The conclusion from these simple statements is that temperatures will increase because of man's contribution. There has been a body of work already indicating these three criteria already exist. Predictions based on these criteria may be inaccurate or may be incomplete due to other forces at work not included in the model, but that doesn't make them wrong for what we know.
Skeptics may disagree with the recommended actions and they may disagree on the predictions based on the gathered evidence, but to refute the science behind the prediction, skeptics need to provide the evidence to the contrary. It also helps if they also can follow the scientific theory and come to a conclusion of their own. Bonus points for including other scientific works (even the work they're trying to refute) in their research. Skeptics seem to have a vested interest in the status quo. They don't get to push off the burden of responsibility on others just to maintain it. If there IS evidence to the contrary, we ALL benefit from knowing about it, and it is in their best interest to get it published. It would go a long way to holding up their argument.
Simply saying "I don't believe you or your conclusions about the future" is not a valid scientific rebuttal. It is laziness at it's finest and the sign of a closed mind.