Mathis Wackernagel & Susan Burns - Global Footprint Network

Mathis Wackernagel and Susan Burns launched the Global Footprint Network in 2003 because "human beings are using more resources than the Earth can provide, and we are in global ecological overshoot." This husband-wife team developed the Ecological Footprint, a resource accounting tool that measures how much nature can produce in our country and how much we use of it.

"Our work is so much data driven, and yet it's so much about life," says Susan Burns. "And it's not about future generations anymore. It's about my life, our son's life," echoes Mathis Wackernagel.

When he was born, human beings were using half the resources that the planet was producing. We are now using 25% more than what's available, and it now takes a year and three months for the planet to recreate what was used by mankind the previous year.

And to conclude: "We are in a new century. In the past you could ignore resources constraints. If you do that in the future, we will be toast."