Over at the Bad Astronomy blog, astronomer and writer Phil Plait has a good post on the subject of climate change that's worth reading. He particularly recommends this short (6 minutes and 30 seconds) video from PBS Digital Studios' It's OK to Be Smart series that quickly goes through two dozen facts on the subject:
Given its brevity it skips over a lot of additional points that could be made.
For example, the most glaring demonstration that more CO2 means a hotter planet is the example of Venus, a planet that's closer to the Sun than we are (so it gets more intense sunlight) but that's shrouded in clouds that reflect so much sunlight into space that all else being equal, we'd expect the surface of Venus to be pretty close to that of the Earth. But it isn't, because Venus as a very dense carbon dioxide atmosphere and consequently a surface temperature in the hundreds of degrees. You can cook a turkey on Venus by setting it outside for half an hour or so.
Also, we know even more directly that burning fossil fuels is responsible for increased CO2 in the air because we have a pretty good idea how much we're burning and how much CO2 that releases, and by itself fossil fuel use is more than enough to account for all the measured increase in CO2. (The excess is being absorbed by the oceans, rocks, and photosynthetic organisms.)
This even shorter (3' 40") video from Hank Green below (also recommended in Plait's blog post) addresses some popular false claims, such as the notion that back in the 1970s there was a consensus for global cooling. (I know first-hand that one's nonsense, because I was an undergraduate physics major at the start of the 1970s and that's when I learned about global warming. Here's an earlier post from this blog that includes a clip from a 1958 Bell Telephone science special on the weather that covered the subject of human-caused global warming.)
Finally, Plait also recommends this succinct list of myths and corrections from the Skeptical Science website: http://www.skepticalscience.com/argument.php.by