is global warming a consensus? (please respond with comments)

My parents periodically email me articles about various scientists who are outspoken global warming skeptics. Usually I ignore them, as I'm aware that in any field, you can find a few nuts, regardless of how strong the consensus view is. This is certainly true in my field (John Hagelin, if he counts as a physicist still). And I'm not prone to believing in conspiracy theories, which is what it looks to me like you'd have to believe in, in order to deny global warming. However, a few days ago they emailed me this article, which claims that less than half of published climate scientists endorse global warming. This is directly contradictory to pretty much everything else I've heard, both in the media and through talking to other academics (and having attended a lecture or two on global warming by climate scientists). I'm putting this out here in the hope that someone knows what the heck they are talking about in this article, whether there is any truth to it, and if so if it is misleading:

Breaking News: Less than Half of All Published Scientists Endorse Global Warming Theory

The above article is linked off of the US Senate Committee on Environment and Public Works, so it does not appear to be an obscure or extreme right-wing biased source.

The main reason I need comments on this is that I'd like to respond to the email I got, but I don't know enough about global warming science/politics to comment on it. But if it is true, then I think many people should know about it as this is not the impression that most people I know (including myself) have regarding the current consensus. Thank you, livejournal users!