By relying on the miracle of fossil fuels we have grossly overshot the carrying capacity of our planet. Fossil fuels have provided cheap, very portable energy, but it has also enabled industrial food production to feed far more people than sustainable agriculture practices can ever hope to feed. Without the fossil fuel based fertilizers crop yields will return to normal levels and the land used sparingly to avoid depletion of all the natural nutrients. Even our crops have been altered to rely on petroleum based fertilizer to the point that the very plants will die without the additional nitrogen.