While making my mind maps I started looking at the idea of global warming being a snowball effect - it gets bigger and we may or may not be able to control it - and I'm thinking of using this to help me illustrate my metaphor.
I'm looking at places you wouldn't normally find snowballs e.g. the desert so I'm looking at sand as well as snow. I started experimenting on photoshop trying to morph sand into snow. Bare in my mind its my very first attempt at photoshop :P