One tragic example of the loss of forests and then water is found in Ethiopia. The amount of its forested land has decreased from 40 to 1 percent in the last four decades. Concurrently, the amount of rainfall has declined to the point where the country is rapidly becoming a wasteland.

Throughout most of my life, I raised tobacco. I want you to know that my own hands, all of my life, I put in the plant beds and transferred it! I hoed it! I've dug in it! I've sprayed it! I've chopped it! I've shredded it, spiked it, put it in the barn and stripped it and sold it!

There's such a wide variation in tax systems around the world, it's difficult to imagine a harmonized CO2 tax that every country agrees to. That's not in the cards in the near term. But the countries that are doing the best job, like Sweden, are already doing both of these. I think that eventually we'll use both of them but we need to get started right away and the cap-and-trade is a proven and effective tool.

As human beings, we are vulnerable to confusing the unprecedented with the improbable. In our everyday experience, if something has never happened before, we are generally safe in assuming it is not going to happen in the future, but the exceptions can kill you and climate change is one of those exceptions.

The good news is, we have everything we need now to respond to the challenge of global warming. We have all the technologies we need, more are being developed.... But we should not wait, we cannot wait, we must not wait.

We can believe in the future and work to achieve it and preserve it, or we can whirl blindly on, behaving as if one day there will be no children to inherit our legacy. The choice is ours; the earth is in balance.

Two thousand scientists, in a hundred countries, engaged in the most elaborate, well organized scientific collaboration in the history of humankind, have produced long-since a consensus that we will face a string of terrible catastrophes unless we act to prepare ourselves and deal with the underlying causes of global warming.