Chapter three is a summary of the current state of scientific knowledge about climate change, focusing on temperatures. It considers questions such as "are temperatures rising and how do we measure them?", "are human activities responsible for global warming?", "what are the expected changes over the next century?" and "what are the likely effects of these?". In forty pages this is obviously only a summary, but it is a solid presentation: the most recent (2007) IPCC report wasn't available, but much of the work it drew on is used.
Chapter four considers possible policy responses to global warming. Adaptation will be a key part of response to climate change, but "mitigation" measures, to reduce emissions of carbon dioxide and other greenhouse gases, will also be essential. Models here depend on emission trends, economic growth, and technological progress. Key policy tools, available at national and international levels, include carbon taxes and cap-and-trade permit systems. (A brief appendix presents some basic economics, looking at discounting, marginal costs, and permit trading.) Any such systems need to carefully constructed and timed so as to provide the right incentives, both for individual states and for businesses.
Putting it all together in some kind of cost-benefit analysis or "integrated assessment" is difficult and involves major uncertainties:
"alternative plausible specifications can increase the optimal reduction in twentyfirst-century emissions from less than 10 percent to more than 80 percent".Geoengineering possibilities are briefly touched on.
Chapter five considers aspects of the current "impasse". Dessler and Parson describe the lack of progress on international policy and some of the criticisms of the Kyoto Protocol. Turning to the science, they write:
"It is not possible to address all the erroneous and misleading claims advanced in the climate-policy debate. They are too numerous, and they are also a moving target."But they tackle some of the less patently false arguments of the "skeptics", about the reality of warming, its cause, and its likely magnitude. More generally, they consider policy skepticism in the face of uncertainty, sound science, and the status of IPCC reports.
Dessler and Parson conclude with some recommendations of their own: they argue for attempting to keep warming below 3 degrees Celsius and atmospheric carbon dioxide below 450ppm, and recommend a "tradable emission permit system including an escape valve". As possible alternatives to sticking with or reforming the Kyoto Protocol, they suggest a bilateral agreement between China and the United States, or a "coalition of the willing" of committed developed nations, with trade levies to prevent global disincentives.
The Science and Politics of Global Climate Change is an excellent overview of the topic, suitable for lay readers but potentially also policy-makers and scientists seeking a broader perspective. For those who want more, each chapter has annotated further reading recommendations. It is unfortunately in the wrong format to reach a really broad audience: it is a paperback, but it's a quarto with a recommended retail price of US$40. It would have been a good candidate for Cambridge University Press' sadly discontinued Canto series. In any event, every general library should have a copy.