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?

The failure of world leaders to act on the critical issue of global warming is often blamed on economic considerations.

The future doesn't exist. The only thing that exists is now and our memory of what happened in the past. But because we invented the idea of a future, we're the only animal that realized we can affect the future by what we do today.

If America wants to retain its position as a global power, its president must listen to the people and show strong leadership at this turning point in human history.

I need quite a lot going on, so a perfect holiday for me is one in a cooler climate with wonderful scenery, animals or great architecture.

If we brought the mammoth back to Siberia, maybe that would be good for the ecosystems that are changing because of climate change.

But Australia faces additional regional and global challenges also crucial to our nation's future - climate change, questions of energy and food security, the rise of China and the rise of India. And we need a strong system of global and regional relationships and institutions to underpin stability.

Make it so people can actually find good housing, can find good quality jobs and can afford to live - then we can weaken the climate of insecurity and fear that allow people to be exploited to increase division.