The Earth is a unique system in the universe, the only planet we know of that's hospitable for humankind.

We have an atmosphere that is roughly 21% oxygen. The rest of it is largely nitrogen. There's just enough carbon dioxide (CO2) to drive photosynthesis. That has been, throughout the history of our species, pretty stable. Until recently.

Ice ages have come and gone. Coral reefs have persisted.

Humans have always wondered the big questions, "Who am I? Where have I come from? Where am I going?" It's part of human nature. It's perhaps the underpinnings of religion.

The concept of 'peak oil' has penetrated the hearts and minds of people concerned about energy for the future. 'Peak fish' occurred around the end of the 1980s.

We have become frighteningly effective at altering nature.

Only two percent of the ocean is fully protected right now.