Earth no longer habitable in 100 years?

These are the words of Stephen Hawking today. But what's a little irritating is the fact that it has up to -120 degrees in winter on Mars. How should a human being survive here? I myself have the most confidence in private rocket companies. Because there is no oxygen on the red planet, so this is again difficult for all people, because they have to walk around in the space suit and the way must be thermo-insulated. In addition, how to get from the earth to Mars quickly, because to understand it, the earth is still the supermarket and Mars the helpless Haus.Dazu would need a drive that is infinite, efficient and effective, as the science first still working.