I don't know about being labelled a 'lunatic'. If anyone could provide evidence that the world is not warming as a result of the extra greenhouse gases that we are pouring into the atmosphere then they would have to disprove numerous theories to do so as well as provide observational evidence. Despite lots of people saying 'it must be wrong', no-one has disproved the basis of AGW nor provided observational evidence showing the earth is not warming.
In fact, each decade is hotter than the one before. Ordinary people are already seeing the effects of AGW on extreme weather each year.
Seems to be a human trait to deny the unpalatable. It's even described as one of the stages of grief. Denier is a more appropriate label for deniers than lunatic :)
As for scientific theory 'being accepted as fact' - most people view accepted scientific theories as fact. Even those that have been shown to not apply in certain circumstances (like Newton's Laws) are accepted as fact and used extensively outside of quantum physics. Once something attains the status of 'scientific theory' it is, to all intents and purposes, a fact.
