Visit this climate blog for a physics maven's responses to the arguments that question global warming. Better yet, take the science with you: There's now an iPhone app that provides answers to common misconceptions and questions.
Here's a link to the top skeptic arguments and what the science says. For example:
Skeptic argument: "It's the sun."
What the science says: "In the last 35 years of global warming, the sun has shown a slight cooling trend. Sun and climate have been going in opposite directions."