I agree with several here - don't underestimate your influence as a parent. We live in ultra-liberal Oregon and my high-school son has had many-a-day since elementary school where he had to listen to senseless dribble from his teachers. We've always discussed these things at home and, most of all, taught him critical thinking. Teachers come and go, but you'll always be their parent - they actually DO listen to you, even as a teen (contrary to popular belief).
Oh, and definitely show him the "Great Global Warming Swindle"!! My son and I watched it a while ago - he loved it and has used some of the information there to refute and educate his brainwashed friends.
Hold strong!