Skeptical Science, gets skeptical about global warming skepticism! A fantastic website. A great teacher-backgrounder: when a student says but "Mars is getting warmer" or "the Medieval warming was warmer," you don't need to be a NASA expert you can go to this site to get the hard science!

Scientific skepticism is healthy. Scientists should always challenge themselves to improve their understanding. Yet this isn't what happens with climate change denial. Skeptics vigorously criticise any evidence that supports man-made global warming and yet embrace any argument, op-ed, blog or study that purports to refute global warming. This website gets skeptical about global warming skepticism. Do their arguments have any scientific basis? What does the peer reviewed scientific literature say?

And see the Most Used Climate Myths: a summary of global warming and climate change myths; for each myth there's what the sceince says at both a "basic" level and "intermediate" level.