In order to test an idea in science you build an experiment and test it. What better way to build a climate change experiment than using Mars.
Our current understanding of climate change relies on computer models and small scale experiments. As climate change is something we want to avoid (on Earth) it is obviously not a great idea to let it happen and just watch. The only solution for developing a good planetary scale model is to run an experiment on another planet.
Not only is Mars close to us, its chilly -60ºC surface temperature could do with a bit of warming up. Not only would this experiment teach us a huge amount about climate, if ‘successful’ we have the beginnings of a new human habitable planet to live on.