With an estimated population of nine billion people by 2050, we cannot continue to consume resources at the same rate and maintain our quality of life.

And that, quite simply, is the issue. We live in a finite world with finite resources. Although it may sometimes seem quite big, earth is really very small - a tiny blue and green oasis of life in a cold universe.

My earliest memory from childhood is of fishing with my father. And I remember vividly we were in a store, and we were buying a pup tent to go on our first camping trip.

Each of us now has 2.27 kg (5 lbs) of plastic embedded in our bodies.

Humanity is facing a challenge unlike any we've ever had to confront. We are in an unprecedented period of change.

We're in a giant car heading towards a brick wall and everyone's arguing over where they're going to sit.

I've always been more interested in organisms that can move on their own than in stationary plants. But when I canoe or hike along the edge of lakes or oceans and see trees that seem to be growing out of rock faces, I am blown away. How do they do it?