A comment on my post "Why I don't want kids" mentions the impact our daily activities have on this world. That reminds me of a conversation I ha with someone a while ago. A US TV show took a suburban family and calculated that if everyone in the world lived the way they do, they would need 12 planets to provide the resources required. This family was then sent to live with a group of extremely environmentally aware people. They had only installed their first solar-panel just after the family arrived.
After a week (or so) of living with them, it was calculated that to live the environmentally friendly way would require 1.8 planets to provide the resources required.
This made me think: if living as environmentally aware as possible requires 1.8 planets, then how are we ever going to address the current imbalance? Of course we could try to repair the planet at half the rate we're damaging it in order to bring that number down to just under 1 planet, but there's something more fundamental than that.
This planet wasn't designed to support 6.5 billion people. If the value of 1.8 above is correct, then this planet cannot naturally sustain more than 3.6 billion humans.
The numbers here are for illustrative purposes only. The quoted number of planets required to sustain a given style of living are based on information from a friend whose memory might or might not be reliable. The population this planet can support is dependent on many other factors, including other animal populations.