I don't know if you've seen the recent books such as Tim Flannery's The Weather Makers, or obviously there is Al Gore's movie. Those are the popular things. The weight of evidence suggests that we're facing significant ecological damage and we have already seen evidence of it as a result of the carbon dioxide levels in the atmosphere. If ever there was an example around applying precaution, that's the one.
On June 5th, 2006. See this statement in context.