We can now return to the assessments of the national interest and discussion of the obstacles in the way of good policy with which we opened the book. We have to decide whether it is in our national interest to do our fair share or to lag behind others in the mitigation effort. Then we have to decide how we go about doing our fair share.

In forming our assessments of the national interest, two main questions have to be answered: Is the science legitimate? And what is the relationship between what Australia does and what the rest of the world is doing?

On the first question, the material presented in Chapter 1 confirms the central propositions from the science beyond reasonable doubt. The central propositions of the mainstream science on climate change are accepted by most Australians. This provides a basis for effective policy action.

On the second, there would be no reason to participate in a global effort to reduce greenhouse gas emissions if there were no prospect of effective global action. Chapter 4 demonstrates the reality of widespread international action to reduce emissions. This has shifted the world well below business-as-usual emissions growth. Current action holds out the possibility of evolution into strong global action that realises the international community's objective of holding temperature increases to below 2°C.

Here we are dealing with facts, not beliefs. I hope that people who oppose Australian action to reduce greenhouse gas emissions on the grounds that others are not acting will directly respond to the facts presented in this book.