I previously posted about the scariest global warming graph I've ever seen. This was a graph from an MIT Study that shows there is a 50% chance the world will warm by 5ºC by 2100 under business-as-usual. I might as well said that an asteroid is heading for earth! Yet, we humans do not react to threats that are not visible, immediate, caused by an enemy, or that do not have historical precedent or simple, personal consequences -- even if it's the biggest threat mankind has ever faced!
To help put the threat in terms that people can relate to, I offer the following illustration:

This is a non-scientific illustration of possible global average temperature increases compared to crashing your car in a brick wall at various speeds. And note that you have no air bags, no seat belts, and all your children and future grandchildren are in the back seat.
You can view a recent talk I gave on climate change at FORA.tv. The talk is 52 minutes long plus about 15 minutes of Q&A (sorry for the limited AV set up in the hall). The MIT Study is discussed in Chapter 4 and the Car Crash is Chapter 5 (you can skip to chapters after the ad plays). You can get more information and copies of the slides at my website, ClimatePlace.org.
I've come to the conclusion that climate change is the biggest psychology and marketing communications problem we have ever faced. We must quickly get people (especially our elected leaders) to understand the clear and present danger that climate change poses. Suggestions on how to achieve this will be appreciated!