The authors make a valid point. However, I suspect that we have a different view as to what constitutes "limited" and "marginal". Let us suppose that by some action we could reduce the average person's "consumption and waste" in the western world by 50%, an optimistic target at best. Logically that might reduce the Canadian "footprint" from 4.3 ha to 2.15 ha. That is still more than five times that of the East Indian footprint of 0.38 ha.
That is, if we are to really create a "sustainable" society we have to tackle the problem by orders of magnitude and not just percentage fractions.
As a point of interest, the Wackernagel and Rees book was published in 1996. In 2002, I received an update from Professor Rees in which he stated that "more recent estimates put the Canadian eco-footprint at about 7.6 to 8.0 ha/capita". This suggests that the problem today is not only substantially worse but that we are rapidly losing ground (literally!)
Data published in a booklet entitled Canada and the State of THE PLANET, indicated that in 1994 only one fifth of the world enjoyed the high level of economic activity while all the rest existed in poverty. If this relationship holds true for our respective economic footprints, then it means that if every one on earth had an equal consumption level, it would be around 2 ha per person. That is to say, the poorest people in the world would be elevated by 4 times, but the "standard of living" of the western world would be reduced to 25% of its present level.
Can anyone in the West seriously imagine what that would be like? Or can anyone imagine any political party receiving a mandate from the popular vote to implement such change? I rather think not. So much for our "ethical obligation to share the wealth". But let me hasten to add, no one should decry any effort to reduce unnecessary consumption and waste - of which there is plenty. Indeed, we should all be making very effort to do so. But the point is, that alone simply does not solve the problem.
If civil engineers can discuss the substantial social changes implied by the subject of "Consumption and Waste" reduction, why should they feel obliged to ignore the much more damaging variable of population size? After all, both are subjects of social behavior and not of professional engineering.
Indeed, I suspect that we could be doing more harm than good by implying that people should not worry because we civil engineers have a solution: building even more infrastructure works that occupy even more land of which the world is already far too short.
A simple case of Emperor Nero fiddling [around] while Rome burns.
5. Keating, M., Canada and the State of THE PLANET: The Social, economic and environmental trends that are shaping our lives, Oxford University Press, 1997, p65