Personally, I don't know whether there is any significant long term warming occuring on the earth and even if there is to what extent it is effected by man's actions. The science is far from a consensus although there is far more effort in attempting to prove and predict global warming than there is about disproving it, on top of that any information which conflicts the assumption that Global warming is occuring is generally not reported on; this leaves us with the impression that there is no one in the scientific community who doesn't believe in man made global warming.
I do know that we're being manipulated to believe in global warming for reasons that have little to do with the planet. Al Gore stands to make hundreds of millions of dollars if he can convince people, companies and governments that Global Warming is an issue because he is one of the primary investors in a carbon trading firm. In Canada and the United States there is the motivation to make Global Warming a major political issue in the upcomming elections because it is believed that Liberals and Democrats are stronger on the issue than the Conservatives and Republicans.
As for Environmental lobby groups they should generally not be trusted. Patrick Moore (a founder and former president of Greenpeace) had the following to say:
"See, I don't even like to call it the environmental movement any more, because really it is a political activist movement, and they have become hugely influential at a global level"
"By the mid-1980s, the environmental movement had abandoned science and logic in favor of emotion and sensationalism. I became aware of the emerging concept of sustainable development: balancing environmental, social and economic priorities. Converted to the idea that win-win solutions could be found by bringing all interests together, I made the move from confrontation to consensus"
Anyways, one more quote from Patrick Moore on this subject which I think is appropriate:
"It's become so complicated, there's so much snake oil around the whole subject... the best comment that was ever made was by Michael Crichton in his book State of Fear: 'I am certain there is too much certainty in the world'. And I am certain that he is right"
