In 1972, The Limits to Growth modeled the effects of unlimited human expansion on the planet's finite resources. Now, 40 years later, the predicted models are still a near match with reality.
The Limits to Growth was written by MIT researchers Donella H. Meadows, Dennis L. Meadows, Jørgen Randers, and William W. Behrens III on commission by global think tank, The Club of Rome. It examined five variables of interaction between people and the planet—world population, levels of relative industrialization, amount of pollution, worldwide food production and the rate of resource depletion. It posited that, with unchecked expansion, the world's supply of resources would falter and begin to fail by 2030. And, as you can see from the graph, humanity is apparently well on its way towards meeting that goal.
This would result in a massive worldwide economic catastrophe and result in an sharp and ongoing reduction in the human population for generations. However, the alternative to this model—austerity measures as we've seen in Greece but on a global scale—could potentially spell financial ruin for billions. So do you want to be poor and hungry or poor and hungry during an economic apocalypse? [Smithsonian]