Lots of death knells out there to frighten people like petros. One for global warming isn't going to ring out because of some minor politician like Harper counting on people being befuddled by bs. That won't stop the deniers from trying to derail Intelligent discussion with wholly unrelated nonsense. Since the world is generally a pretty great place to have those discussions and therefore worth minor aggravations you just have to exercise restraint patience and a sense of humour.