Yes, the fact that the globe is warming is not disputed, but the causes are.
Among natural climate forcing factors, the most important have been the changing incoming Solar irradiance due to variations in Earth's orbital parameters, and the cloud effect of aerosols from volcanic eruptions.
Regarding the human activities are the 'greenhouse gasses', carbon dioxide, methane, nitrogen oxide, ozone, and chlorofluorocarbons (CFCs) have been considered the most influencing on climate.
Carbon dioxide is the main greenhouse gas emitted by human activity. It is responsible for over half the enhancement of the greenhouse effect. The largest single contributor to emissions from fossil fuels is power generation. Transport is another major contributor.
The concentration of CO2 in the atmosphere has increased from about 280ppmv, before the industrial revolution, to 358ppmv by 1994. The concentration of CO2 in the atmosphere has been measured in Mauna Loa, Hawaii since the 1950s.
(I don't know why it's such a squiggly line, though, but it is increasing at an accelerated rate)
Read more:
http://www.ieagreen.org.uk/ghgs.htm
Paleoclimatologists, studying the global temperature variations across millenia, suggest that solar irradiance and volanism may be responsible for 41-64%, while natural variability and human-induced greenhouse gas is needed to reproduce the rest.
Read:
http://www.eurekalert.org/pub_releases/2003-01/su-eog123002.php
http://www.pewclimate.org/global-warming-basics/
Yes, the global warming would
never have the ridiculously accelerated effects as in the film, but it is causing unnatural effects on the weather, effects only seen in the last 200 years, after the industrial revolution. It's ridiculous to assume the tremendous increase of fossil fuel combustion over the last 200 years would have no environmental effect whatsoever.
[This message has been edited by Mort-Hog (edited June 01, 2004).]