First, I'd politely suggest that the first step toward constructive discussion is not to patronize the person you're talking to. Condescension might make you feel great, but isn't a great way to start a difficult discussion.
OTOH, if you're actually genuine about believing that "anyone who doesn't agree with global warming doesn't understand science"...then you might want to check your biases. There are a LOT of scientists - including some climatologists - who disbelieve the all or parts of the current paradigm that "the planet is warming and humans are the main cause". Let's use, for example, Dr. John Christy, professor of atmospheric science and director of the Earth System Science Center at the University of Alabama Huntsville (UAH) who's shown that observed temps are *radically* different than pretty nearly all the climate models put forward by the IPCC: http://www.cnsnews.com/sites/d... ...if that doesn't make you suspicious of "sky is falling" predictions by the IPCC, what would?
As you posted AC, and I don't even know if you'll come back to respond, it's not worth a comprehensive discussion here, so I'll be as succinct as possible. (If you do come back, and want to have a constructive dialogue, I'd be happy to.)
First, we'll set aside all of planetary history before the last 3m years (because they were warmer), I'd invite you to look at this: http://upload.wikimedia.org/wi...
or more zoomed in for specifics: http://upload.wikimedia.org/wi...
There are *clearly* nearly-vertical temperature and CO2 spikes every 100k years or so. The last one was about 100k years ago.
If something happens repeatedly, say, a dozen times in a row, in a reasonably consistent cycle, and then it happens a 13th time, a reasonable observer is going to assert that what ever caused the previous 12 is causing the 13th, and whatever caused them to end will ALSO cause the 13th to end. The fact that you happen to be present to see the 13th, doesn't mean you're the cause.