A little control takes heat off

Two of the great issues facing the world are global climate change and changes in the size and nature of human populations. The two are inextricably interwoven. On the one hand, the size and prosperity of the world's population may impinge on the amount of greenhouse gas (GHG) emissions that occur in future. On the other hand, climate change will itself have a range of impacts on societies. The aim of this book, which has its parentage in the International Institute for Applied Systems Analysis, is "to delve deeply into the intricate relations between shifting climate and population changes such as where people live, where they move to, how they propagate and how they die. It is also the first book to take a dispassionate, scientific look at how population affects climate change and society's ability to adapt to it."

The way in which this aim is approached is clear and logical. The book is divided into two parts. The first provides overviews of the climate outlook, demographic prospects, and economic perspectives on population, development and the environment. The second seeks an analysis of three major links between population and climatic change: the role of population growth and structure in GHG emissions, the effect of that growth and structure on the ability of societies to withstand the expected impacts of global warming, and the implications of global warming for population-related policies.

In themselves, the three chapters that make up part one are model reviews that provide convenient primers. They also stress uncertainties - uncertainties are legion. However, the strength and originality of the book lies in part two. The answer to the question of whether demographic changes will have a significant impact on GHG emissions is relatively clear: "Our central conclusion is that policies to encourage more rapid demographic transition are likely to significantly reduce GHG emissions in the long run. It appears unlikely that age-structure effects (such as the impact of population age structure on the number of households) or indirect effects (such as the possible relationships between the rate of population growth and the rate of per-capita income growth) are strong enough to reverse this direct effect."

With regard to another question, our ability to be resilient in the face of climate change, the answers are less clear: "The expected impacts of climate change could threaten agriculture, health and environmental security, especially in less developed countries. This does not mean that climatic change is expected to make living conditions worse than they are today; rather conditions are expected to be worse than they would have been in the absence of climate change." Nevertheless, lower fertility would improve the ability of developing countries to adapt to the expected impacts of climate change.

The final chapter of the book looks at the arguments for population-related policies (such as voluntary family planning) and argues that such policies are "no-regrets policies" in that they not only improve the welfare of the least well-off, but will in the long term reduce GHG emissions and improve the resilience of vulnerable populations to climate-change impacts. Moreover, policies in the LDCs that result in lower population growth will confer an external benefit on future generations in the more developed countries because of lower GHG emissions.

The team that put this book together has done a good job. The concepts of climate change, demography and economics are expressed with clarity. The integration of natural-science and social-science perspectives is achieved with great success. Acronyms and jargon, beloved of the international policy set, are refreshingly sparse.

Andrew Goudie is professor of geography, University of Oxford, and editor of The Encyclopaedia of Global Change .