365 Days of Climate Awareness 101 – The Limits to Growth, 30-year update

Twenty years after publishing the landmark world modeling study “The Limits to Growth”, Donella Meadows and her system dynamics team composed a second edition, “Beyond the Limits”. This book examined evidence from around the world that physically humanity was already in overshoot, extracting too many resources and polluting at too high a rate for the planet to support. In 2000 they set themselves to re-evaluate the global state of affairs against the 1972 model results. Not to answer an overly simplistic, “Was the book right?”, but to examine how well the World3 model compared to three decades of events.

“[W]e can report that the highly aggregated scenarios of World3 still appear, after 30 years, to be surprisingly accurate,” Meadows wrote in the preface. Many parameters, such as population (6.0B, up from 3.9B) and annual grain equivalent production (3.0B, up from 1.8B) matched actual data well.  “Does this correspondence with history prove that our model was true? No, of course not. But it does indicate that World3 was not totally absurd; its assumptions and our conclusions still warrant consideration today.”

The book summarizes the philosophy behind the original, at times illustrating it with newer concepts. The problem of overshoot is described, along with the driving force—exponential growth—behind it. Then it describes the limits: sources (of resources) and sinks (for our waste products). After detailing the World3 model and its results, it tells a success story, how we, collectively among nations, dealt with the global problem of the Antarctic ozone hole (acid rain is another success story). The book then moves to present challenges facing us, and the fitness of the capitalistic free market to confront them, and later moves on to the future, and how we as a race might achieve sustainability.

Economist Arthur Daly identified three rules of economic sustainability. Those are:

1.    Renewable resources: rate of consumption cannot exceed the rate of replacement;
2.    Nonrenewable resources: rate of consumption cannot exceed the rate at which it can be replaced by a renewable alternative;
3.    Pollution: rate of emission cannot exceed rate at which it is absorbed, recycled, or rendered harmless.

Another useful supporting concept, made popular by ecologist Arthur Wackernagel is that of the “ecological footprint”, estimating the amount of land needed to support a given activity. He estimated that, in 2000, humanity required 1.2 earths to support its current level of consumption.

The book ends hopefully, pointing ways forward to sustainability, though without any assurance we will achieve it. We are now approaching the 50th anniversary of the original book, and our overall ecological footprint is estimated to be about 1.7 earths. Despite global decades-long conversations about the problem, we have backslid by nearly 50% from 2000 in the drive toward sustainability.

Tomorrow: brief states of the climate 1: 2010.

Be brave, and be well.