In these early years of the 21st century there are two related challenges facing human civilization. As the global economy continues to grow and consume more energy, what happens when we start running out of non-renewable fossil fuels? And how do we find a safe way of burning these traditional fuels, given the negative effect they have on the environment?

The six essays presented here by various experts in the field don’t even try to solve this double bind. Instead, the goal of the book is to view the issues “through the eyes of those who think about them rigorously.” The results are informative and the discussion stimulating, but the overall effect is mixed, because those who think about these subjects rigorously are by no means in agreement about them.

In the first essay, for example, David Keith argues that climate change is the greater threat to our civilization, because we have plenty of energy resources to keep us going for centuries. Next, J. David Hughes flips this around and says that energy is the more urgent problem because in fact we are running out of cheap hydrocarbons. Keith sees coal-to-liquids technology as one solution to the problem; Hughes dismisses the same process as “a complete non-starter.” Hughes places heavy emphasis on an analysis of declining Energy Return on Investment (EROI), but in the next essay, by Mark Jaccard, this calculation is challenged with a different economic model. It’s hard to imagine working together on solutions when there is so little consensus about the exact nature of the problems.

As Keith sees it, the twin carbon crises are characterized by high uncertainty and high inertia – the former represented by the mixed messages Carbon Shift delivers, and the latter exemplified by the dismal political response outlined in the final essay by Jeffrey Simpson. Homer-Dixon adds a conclusion that attempts to provide some coherence to the different points of view as well as suggest a very general plan for action. But while a case for radical change is made, Homer-Dixon admits that “logic alone isn’t going to cause us to act.” Things are going to have to get worse before they start getting better.