This has been around a long time and there are many variations of it. I was sent this by a group called "Big History". Too many of us think we can keep on increasing our numbers and nothing will happen. I keep asking the question: how many people do you think the Earth can hold - 10 Billion, 100 Billion or more? No one has yet to answer. Overpopulation is not a myth it is the mother of all drivers including Climate Change. Take this test and see how many Earth's it would take to sustain your lifestyle (even with my trying I still need 1.5 Earth's).
Another link to the site is: [footprintnetwork.org]