Why we should think bigger about public health — way bigger.
The human footprint on the earth has grown explosively over the past century or two. Two hundred years ago, there were about 1 billion of us; today, we number more than 7 billion. We have harnessed vast amounts of energy, cleared countless forests, dammed thousands of rivers, reconfigured entire coastlines and built vast cities. We appropriate about half the planet's accessible fresh water and nearly half the desert-free land surface to feed ourselves.
