The chart is based on a sort of 'business as usual' reference case, as they say:
"the way the world would emit GHGs if either there were no consequent climate change or we were completely ignorant thereof".
There is a later chart which shows temperatures being kept under 2 degrees C based on their "Fair Plan emissions trajectory".
Yes these are all modeled projections, but we don't have an alternate earth to experiment on.
Don't try and tell me you don't do any modeling in the mining industry e.g. pit optimisation? How else do you do it when you don't have an alternate pit to try things out on? You do it by building a model.