temperature of the earths surface, and the other part - the colored parts - are actually modelled these,gcms, global climate models, versions of the surface temperatures the first thing i point out, is if you look up to the middle part of the 1900's, what you see is the models replicate observations pretty well. now what i should say is there's two versions of the models run here and this is the beauty of models. we can run them, within this case greenhouse gas enforces included or excluded. the blue envelope is the set of model runs done without greenhouse gasses and the red envelope is the one with. so the message here is that up until about 1970, the two families follow each other pretty closely then they start to diverge. the reason they diverge of course, is greenhouse warming is becomeing a stronger influence and the actual earth climate is starting to feel that and depart from what it would look like if - i can't get the pointer to work - but if we only had natural variability, which you can see by the end of the 20th century the difference between modelled with natural variability an