Tomorrow's climate is today's challenge We all tread on the world, pressing down on it by the way we live. Some of us tread on the world heavily and leave a large footprint. Some of us tread on the world lightly and leave a small footprint. The Ecological Footprint is a measure of the amount of natural resources it takes to sustain a given population over the course of a year. humanity’s footprint is 57 acres per person while the Earth’s biological capacity is just 41 acres per person. In what ways do you press heavily on the world by using up lots of our planet’s resources?