Who to believe?
If this forum reaches a concensus on the validity of human influence on climate change then it would probably be the first anywhere! All sides can put out the usual suspects as evidence both ways as witness the Myth/Fact posting previously and the sums on the effect of CO2 earlier. You only get the truth as it suits someones point of view or vested interest and nothing seems to give such entrenched opinions. For what it's worth I have followed (as best I can) the topic in New Scientist for some time and whilst they may of course have a vested interest (not sure why though) the story does seem that the concensus of most scientists is that climate change is happening and human intervention is having an effect.
One thing I do take issue with though is this "Save the Planet" message from the more extreme tree huggers; the planet will be fine without us and frequently does it's best to get rid of us in big numbers!