The Science and Politics of Global Climate Change is just what its subtitle asserts: a guide to the debate -- or perhaps the debates. The combined expertise of Dessler (a climate scientist) and Parson (a professor of law) allow them to summarize several debates regarding the scientific facts about climate change, its causes, its likely consequences, and the wisdom of various mitigation and adaptation strategies.
Global Climate Change's first chapter briefly sets the stage for the work, laying out the fundamentals in the scientific and policy debates. The second chapter gives a brief description of the scientific method and attempts to distinguish and clarify empirical and normative claims made in the wider public debate on climate change. The best of the work begins in Chapter Three, which provides an admirably clear account of what is known about climate change and its likely consequences as of the time of publication. The conclusions are based largely on the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) and other special reports published by the Panel. Some subsequent material is included to bring the findings up to date.
The conclusions of these reports show significant global warming and argue that it is caused mostly by our production of various greenhouse gasses. Consequently, the fourth chapter outlines adaptation and mitigation strategies and discusses their costs and benefits. Finally, the fifth chapter describes the political debates related to responding to climate change. In each chapter, Dessler and Parson give an even-tempered presentation of the main arguments of the parties to the debates, but without withholding their own views. Usually, these views assume the middle ground of various ranges of uncertainty described by the IPCC.
Among the more interesting elements in Global Climate Change is Dessler and Parson's the treatment of "the climate skeptics," i.e., those who believe some number of the following claims, (1) the Earth is not warming, (2) the Earth may be warming, but human activities are not responsible, and (3) future climate warming will almost certainly be very small. The authors address these claims directly in the last chapter, but much of what is in the third chapter is sufficient to rebut the claims. There, Dessler and Parson examine five natural factors that might cause the climate to change: orbital variations, tectonic activity, volcanoes, solar variability, and internal variability. The authors conclude that none of these factors are significant enough to account for the rise in the global temperature during the past century. At most, they are able to explain small fluctuations or minor deviations from the general warming trend. Indeed, the best climate models include all these factors and human activity in the explanation of the data.
In brief, Dessler and Parson definitively reject the skeptics first claim, believe that human activity has likely caused most of the recent temperature increase, and caution us not to believe that climate change won't be a significant problem in the future. They write, "If climate change lies near the low end of the projected range, impacts over the twentyfirst century are likely to be manageable for rich, mid-latitude countries, but may pose serious difficulties for poorer countries. If climate change lies near the high end of the projected range, impacts over the twenty first century are likely to be severe and potentially unmanageable for everyone." Unfortunately, they dedicate only six pages to describing these impacts. For a readable and well organized treatment of the impacts, see The Rough Guide to Climate Change by Robert Henson -- London: Penguin Books, 2008.
Global Climate Change is an excellent treatment of the debates, but since its publication, the gravity and certainty of the conclusions in the climate change debates have increased. For the most current information on the scientific aspects of the debates, one must read the Fourth Assessment Report of the IPCC (2007). It is available at http://www.ipcc.ch. The report is presented by three working groups covering "The Physical Science Basis," "Impacts, Adaptation and Vulnerability," and "Mitigation of Climate Change." Each group provides a detailed survey of the scientific literature and its main conclusions, along with a kind of executive summary for policy makers. It would be a great contribution to public understanding if Dessler and Parson published a second edition of Global Climate Change based on the IPCC's Fourth Assessment Report.