The next few years will be important in determining the course of world efforts to control climate change. Our eyes and ears are constantly bombarded with claims and counterclaims that I said in the Introduction included the sensible, the senseless, and the self-serving. My aim has been to tell the technical side of the story in an honest fashion at a level for the general public without oversimplifying or hiding the consequences of the choices that must be made. I hope that armed with some facts the reader can distinguish between my three Ss.

Many say that in democracies the people are rarely willing to make hard choices unless they are frightened of the consequences of not making them. Perhaps I am too much the romantic, but I believe that they are willing when the problem is clear and the consequences of action or inaction are clear. I hope you will take a few things away from this book:

• The greenhouse effect is real;

• We are changing the atmosphere and the world is heating up;

• The science is still evolving and how bad things might become is still uncertain;

• Inaction is certain to have serious consequences;

• The longer we delay starting to deal with climate change, the harder dealing with the problem will be;

• The problem is emissions of greenhouse gases and the goal is to reduce them: the world does not have to run only on windmills and solar cells;

• We can mitigate the damage, but have to act on a worldwide scale;

• The richer countries will have to develop the affordable technologies that all can use;

• It will be hard to develop sensible national policies and even harder to develop sensible international ones, but we must try to do so.