The author carefully defines his terms, methods and intentions at the outset. Resource availability, partcularly renewable resources, are a key foundation, since so many social actions result from whether crops, forests and fisheries are plentiful or depleted. While the author argues that wars are rarely the result of resource depletion, internal strife can often be traced to environmental degradation. He cites examples in Mexico, India, African states, Haiti and the Philippine Islands. He uses in-depth studies to present his cases. He's uncompromising in his analyses, but keeping up with his presentation isn't difficult. His prose is clear and undemanding.

A fundamental issue is the expansion of humanity over the planet. He contests the research that indicates population pressures are levelling out, noting that "the largest cohorts of girls ever been born have yet to reach their reproductive years, ensures tremendous momentum behind global population growth." This rise in world population is having local impact already. Resource depletion is causing internal strife along class and ethnic lines, but hasn't escalated into international conflicts, according to Homer-Dixon. Even so, the world is interdependent. He cites the conditions in China as a prime example: "We all have a stake in the success of the grand Chinese experiment with economic liberalization, . . . Whether and how China breaks out of the vicious cycle [of economic growth versus resource depletion] will shape much of human history for decades, if not centuries, to come."

Homer-Dixon's status as a first-rate global analyst was established with this monumental study. He sees "environmental scarcity" leading to civil unrest, with ethnic and class clashes dominating. "Scarcity" refers to resources needed to sustain the growing human population - water, cropland, forest assets, fisheries. How will investing countries/firms react to these conflicts? Environmental scarcity often derided as a source of conflict, but he argues that since daily living requirements are so dependent on these available resources, they become a root cause, even when this is not readily apparent. Although these conflicts usually remain internal, resources such as depleted river water supplies may spark international clashes. He offers no policy recommendations for the lazy. However, his analyse of physical and social conditions should lead to improved policy making. He posits a strong call for more research, itself a major policy step. This book is a must-read for policy makers and those who support them - we taxpayers. It's a vivid insight into to world conditions today and a window into tomorrow.