The geniuses at the MIT Global Change Program have looked at the scenarios for climate change - what kind temperature change we can expect if we do something and reduce our greenhouse gas emissions, or what we are looking at if we don't.
Take a gamble on the wheel of misfortune
here.
An interesting analogy used on the site is one of taking personal responsibility to mitigate risk:
Human-induced climate change is a problem of risk management. It can not be proved that the outcome will be dire or shown with certainty that it will not. As with other problems we face in private life and public policy, from controlling your cholesterol level to defense against epidemic disease, uncertain dangers can warrant reasonable measures to reduce risk.
The answer - take care of the biospshere, like taking care of your heart - do something about it.