I've approved of the environmental messages in some movies. The fact that Avatar had environmental angle wouldn't have bothered me, except for the fact it was so peachy and self-righteous -- and simpleminded.
Cameron is unfortunately one of those people who pays lip service to environmental issues but don't even bother to examine the actual facts.
As someone who cares about environmental issues I am embarrassed by people like him, because they create the impression that environmentalists are all arrogant asses.
However, I'm not a vegetarian. I only use incandescent lightbulbs. I find it absolutely imbecilic that California lawmakers think outlawing the sale of big screen TVs are going to save the Earth.
And I don't believe in global warming. The fact is, there quite simply is no evidence that global warming is a reality, much less caused by man. But say this to some people and they look at you as you're a holocaust denier (or a "$#@!" if you're talking to James Cameron).
If evidence for global warming was so overwhelming why did An Inconvenient Truth need to filch effects shots from The Day After Tomorrow and pass them off as the real thing?

It also boils my blood to hear these Hollywood millionaires telling people "You need to be more environmentally conscious" while they fly around in private jets.