The way I see it is that we will end up having to relocate on another planet at some point because we are tearing through resource and life here. As a human race we are past 7 billion people and counting. That's nuts. Thee resources won't last forever. And I don't think people will sit idle and watch everyone die away. There have been discoveries of similar planets to earth. But so far away. Hence the starts to rudimentary microscopic warp drive concepts and such. It could happen. Not instantly. But It could happen in the future.
Also, Michio Kaku is awesome. Guy has lots of really good information to talk about and is confident about it as well.
Yes, the number is pretty ridiculous. In 1800 the pop. was 1B. It took another until 1925ish to get to 2B. And then it skyrocketed from 3B to 7B since then!!
But I'm in the boat (see what I did there) that our population will eventually level off. As countries become more and more developed, and able to provide education and a higher quality of life, life expectancy, etc. then the underdeveloped countries today where women on average have 5-10 kids will turn to 2-3 kids. The global average is actually 2.5, and was 5 in the mid 20th century. Of course it's the average, cuz for example in countries like Japan, you actually have negative population growth, same in Europe and Russia, but on the other hand you still have the 5+ in developing countries.
The high UN projection that we keep growing at the rate we are now is not taking into account external factors like the ones I mentioned. There are other radical projections that we will actually LOSE people due to war, disease, and such, which IMO take the external factors too much into account.
The middle of the road scenario is leveling off, which I think will be around 10B max and this I think will happen around 2100.
But I def agree that even tho I think we will level off, we will still level off at an insane number. So the environmental and econ. consequences will be...interesting. Even today, parts of the world are running out of water and prices of food and energy and killer.
This is a perfect example of the leveling off. ie. Europe. Asia is trending that way potentially as well.