I haven't seen the movie, but I don't fault Gore for trying. This is a subject on which he has been involved ever since his college days, and one where he seems to have done his homework, so he is hardly an uninformed observer. I personally think he is probably overstating his case in some areas, but the core arguments are pretty solid. Most climate scientists do indeed seem to believe that the earth has warmed over the past century, that it is currently warming and we can observe this warming in our present environments, that it will continue to warm this century even if the extent is unknown, that human activities are at least partially responsible, that at least some affects of this warming are likely to be damaging, and that we can take certain steps now to mitigate potential damages.
Beyond these generalities however, there seem to be vast differences of opinion within the scientific community on the particulars - the extent of change expected, the extent of human contribution, whether specific weather effects (hurricanes, etc) are significantly effected by warming, and so forth. The actual scientists I have read state their conclusions with due caution in most cases, knowing that much more research is needed. The measurement and statistical issues involved in building accurate climate models are daunting indeed, particularly if one hopes to use such models for forecasting, and truly hard measurement data (i.e., direct measurement to X significant digits) on some key variables only goes back a few decades, and none go back more than a couple centuries. Beyond that proxyies must be used. The validity of using proxy measurements, especially multiple proxy reconstructions, to impute key variables from past data is far more difficult to establish than most people realize. Most scientists realize this these days I think. I do think they have made giant strides in the past few decades, and applaud their efforts. But much needs to be done still, and a cautious attitude is still called for.
On the other hand, we have seen in recent years what can only be called mass hysteria by the media on this issue, roused by activists who feel no compulsion to make their case with scientific rigor and humility. I have seen the most outrageous claims utterly unsupported by facts or empirical data. And I have seen outright torture of data to make it fit preconceived notions. The scientific community has done a terrible job of countering the politicization of their research by, frankly, those with strong Marxist, statist, anti-globalization, anti-western, and even anti-human agendas. As a result, we have seen the inevitable counter-reaction by those in political opposition to these types, which has also been willing to use any means necessary to debunk.
Now that I think of it, the current climate (no pun intended) is analogous to the Reformation period. Excesses by one side produces a revolt followed by hardening attitudes and a counter-revolt. And the baby gets thrown out with the bathwater. So goes the culture war.
The British media seems particularly prone to manipulation and hyperbole. Michael Crichton's novel State of Fear (not a particularly good story in my opinion), was filled with poor science, and those who use it to try and buttress a case against global warming only show they have no familiarity with the science. In spite of this criticism, he was correct in his critique of the media on this issue I think, and on the cynical manner in which activists manipulate public opinion.
As with most inflammatory issues, humilty and caution are counters to demagoguery.