The reference in your recent editorial (see Apocalypse now?) to the book Limits to Growth, and the statement that the book of 30 years ago made predictions that failed to materialise, was wrong on several fronts.

First the book has been updated twice — in 1992 and in 2004 — and thus is not as outdated as you imply. Second, the main author was Donella Meadows, and then Dennis Meadows.

Most importantly, the book made no predictions. It presented some 13 different scenarios, informing policymakers of what might happen if certain paths followed their course. The collapse of society was the result of most scenarios but this wouldn't occur for another 25 years even in the most pessimistic scenario.

Also the cause of collapse wasn't running out of any particular resource, as implied in the editorial, but rather due to channelling of resources away from industrial output and services and towards managing growing pollution, as well as the greater inefficiency of extracting increasingly low-grade resources.

Thus the book is valuable in that its recommendations are highly practical, based on real-world modelling (of course, all models are very limited, a point on which the authors expound). This kind of modelling uses our best knowledge of models and offers possible quantified scenarios.

The Intergovernmental Panel on Climate Change (IPCC) also relies heavily on computer models for its predictions and recommendations. I infer from the editorial that the Millennium Ecosystem Assessment relies less on this approach, and is thus more general and broad-sweeping.

Limits to Growth serves well alongside the IPCC as examples of how to offer practical recommendations for global problems.