My favourite analogy for climate change is that the thin layer of carbon dioxide in the atmosphere is like a blanket you have over you on a chilly lie-in morning. Throw an extra blanket on, and pretty quickly you get uncomfortably warm…
A couple of videos
– a carbon history of the world
– “But Carbon Dioxide is only 0.038% of the atmosphere”
For good metaphors to explain all aspects of climate change, check out Climate Bites.
For detailed demolitions of various denialist talking points, see Skeptical Science.