I was talking about risk last night with a couple of friends. I was asked why climate change is a risk to individuals, nations and the world. Here's why. The following distribution describes the estimated chance of different warmings if we give up producing CO2 and other greenhouse gases now (actually if we stopped in 2005). You will see that we have a more than evens chance already of melting the greenland ice sheet (7m of sea level rise, enough to reach the shores of Cambridge). Over the next few years we will reach the same chance of destroying the amazon rain forest (it's even possible that if climate change was compounded by drought, a vast fire might erupt). Big risks.
The commentary "Stop Worrying Start Panicking?" on this is here:
The other thing I've been thinking about is the basic evidence about why the planet is cooking (in particular, how we determine the radiative forcing of different gases). I've found this article which appears quite good: http://www-ramanathan.ucsd.edu/RamAmbio.pdf