from the huffinton post:

a while ago david mentioned peak oil, climate change and overpopulation as the big three... i would add to that the water crisis, already upon us but still in its early stages... for insight on the topic, have a look at the latest issue of nation geographic: http://www.nationalgeographic.com/zinio/freshwater/ when i was a kid they had lions, pandas and native tribes on the cover, now every second issue details a looming crisis...