Stephen Hawking on Global Warming and Colonisation of Other Worlds

BBC reports that Stephen Hawking sends the following message to humanity on Earth:

• Humanity is at risk from a series of dangers of our own making e g global warming.
• Assuming humanity eventually establishes colonies on other worlds, it will be able to survive.
• Disaster to planet Earth becomes a near certainty in the next thousand or ten thousand years.
• By that time we should have spread out into space, and to other stars, so a disaster on Earth would not mean the end of the human race. 
• However, we will not establish self-sustaining colonies in space for at least the next hundred years, so we have to be very careful in this period.

Evidently Hawking believes in man-made disastrous global warming and sees a necessity to escape to other worlds around other stars than our Sun. 

We cite from SkyandTelescope:

• The Sun’s nearest neighbor, Alpha Centauri, is actually a triple-star system —three stars bound together by gravity. 
• Alpha Centauri A and B are two bright, closely orbiting stars with a distant, dim companion, Proxima Centauri. 
• The binary appears to the unaided eye as a single star, the third brightest in the night sky, but it lies 4.37 light years from the Sun — Proxima Centauri claims the honor of being our true nearest neighbor at only 4.24 light years away.
• It’s difficult to conceptualize such vast distances, but a popular analogy sets the Sun at the size of a grapefruit. If you wanted to get from your grapefruit-sized Sun to a grapefruit-sized Alpha Centauri system, you would have to travel about 2,500 miles, which is about the distance from coast to coast on the continental United States. And that’s just to the Sun’s closest neighbor!

So to escape global warming our only chance is to reach Alpha Centauri or beyond, at least 4 light years away, with a lot of material, food and people to build a colony.  Of course clever scientists can make this come true...