I don't think it's impossible for this many humans to live on the planet over time (especially as we improve technology to accomplish more with less).  What I'm more concerned with is how rapidly expanding human population in such a short period of time as we have is degrading the quality of life for those already here.  

We're popping them out (not so much the US, but many other countries... and then they want to come here and ruin it) faster than technology advancement can keep up with.