I have serious doubt that Stephen Hawkings has very high IQ.
What I do know is that he is a prodigy in living with an incurable disease that should have left him dead a few decades ago. That is, if it is really him in the wheel chair now. And not just something to wheel out in front of crowds now and then. He doesn't need a teleprompter, just program his speak-n-say to say whatever you want.
Now, the actual rebuttal.
If we, the human race, don't learn to overcome these societal problems then it does not matter where we go, we will just do the same thing there too.
Using technology for peace rather than war is something we have to learn. And to learn that, we basically have to throw out all the text books in our current govern-cement schooling system. Our schooling system is to create good factory workers and soldiers. It needs to be abolished. When we learn to actually work out differences, and to see win-win scenarios, then our race will turn away from war and towards negotiation.
We have not destroyed our planet. Global warming, if it actually exists, only threatens the infrastructure we built on the coasts without high sea walls. It does not threaten humanity. But! We are moving into a mini-ice-age, so I feel we are quite safe from rising sea levels.
So, to sum up, I do not agree with Stephen Hawkings. Especially in this statement. I also believe that this statement is propaganda designed to unsettle people, and allow people to "believe" it when trillions of dollars disappear into "space exploration".