Global warming - is it happening or not? Considering the winter Toronto just had, with little or no snow and warm temperatures throughout January and February, it's not hard to feel a little concerned about the weather.
There is lots of evidence to suggest that us humans are affecting the climate of the earth, and there are also several coherent expressions of skepticism out there - like Bjorn Lomborg's book, The Skeptical Environmentalist.
Scientific American is promoting a bit more discussion. They have a blogger, George Musser, on the job, answering queries from skeptics about climate change.
Although you have to click through a few screens to get to the good stuff, it's an interesting read.