Limits To Growth is an oddly dispassionate analysis of the challenges we face as a planet in this century. While I have no doubt that the authors are passionate about sustainability, they have let cold facts and careful analysis set the mood. I think I was surprised by the cooler analytical tone because I had heard so many people talk so enthusiastically about the book. What it lacks in temper, however, it regains in clarity.

The central argument is laid out in three parts: (1) Our populations and economies are growing but (2) there are limits to that growth and (3) there are consequences for overshooting those limits.

The chapters on growth and limits are fairly straightforward. There are ‘w’ many people who each consume ‘x’ amounts of stuff, growing at a rate of ‘y’, but there is only ‘z’ stuff available. The most interesting part of the book concerned itself with ‘overshoot’, or what happens when we exceed limits. Here, modeling takes over from data, and the authors make extensive use of the World3 simulation model.

Of course, the engineer in me likes to believe that it is possible, through clever programming, to model the whole world and its various systems with ever increasing precision and granularity. The authors point out that in the 70s, when Limits To Growth was first published, the World3 simulation took hours to run on a super-computer, but now (in 2005) it takes only a few seconds on a laptop computer. That made me wonder why they didn’t take advantage of advances in computing power add more detail and nuance to their modeling, rather than simply getting it to run faster. I suppose that there is a certain beauty in simplicity, and the devil often lurks in details, so on this point I am willing to be forgiving.

The simulations start off being fairly pessimistic, and then become rather grim, projecting large collapses in economic output and population. By the end, however, hope is introduced, contingent not only on significant technological advances, but also a fundamental shift in cultural attitudes towards family size and resource accumulation.

The positive picture of what could (and should) be our future does seem somewhat elusive, and the authors are clear that they are not fortune-tellers. But they suggest five broad principles they feel would be helpful on the journey: Visioning, Networking, Truth-Telling, Learning, Loving. It’s really hard to take issue with such a list. And while it felt a bit like an obligatory hopeful, if not happy, conclusion to an otherwise sobering account, it resonated with the optimistic side of my nature.

The other side of my nature, which is not so much pessimistic as it is realistic, will continue to watch and read with fascination, amazed by the complexity of it all and unsure at each step.