How water issues look from upstream
Is there really a 40,000-year-old bush in Tasmania?
It sure appears to be that old. It clones itself. Suppose what might happen if (perhaps when?) we find ways to replace most of the human body? Assuming we learn to overcome Alzheimer's and other threats to the brain, then the more organs and body parts we learn to replace, the closer we come to a dramatically different world than the one we know.
Farms inside skyscrapers?
That's the idea behind the "vertical farm." The idea isn't completely ludicrous, but it's a bit unlikely, at least for now.