Scratch an environmentalist, and you will often find they believe that there are just too many of our species. This comes through overtly in organisations such as the Optimum Population Trust, which thinks that the population of the UK should be managed down to no more than 30 million. It also lies behind much of the current fuss over climate change: fewer people, less energy, less carbon.
Of course, many of us would probably find it more comfortable if there were fewer people around, but that's different from saying that there is some "optimum" population. The concept is underpinned and justified by measures such as the carrying capacity of the Earth. The Global Footprint Network tells us that we are currently using the resources provided by 1.3 planets. Like any measure, this figure will depend on the assumptions made, but the message is that we either cannot sustain the current world population or must consume fewer natural resources each year.
This is the latest incarnation of Malthusian thinking, and to me suggests a narrow view of life and a lack of confidence in the adaptability and flexibility of the human race. The whole philosophy of sustainability relies on us continuing to progress along the same path as we have in recent decades. It's really a first shot at global planning and, like all attempts at central planning, is deeply flawed.
The reality is that, when there are pressures for change – rising oil prices, reduced food security, etc – we find ways round them. The green revolution of the second half of the twentieth century made nonsense of Ehrlich's predictions of famine and disaster. Private sector development of new and efficient alternatives to the internal combustion engine (in parallel with continued efficiency gains for conventional engines) will lead to a new generation of personal transport. The free market isn't perfect, but it's a much better way of channelling creativity than is government planning.
Guest author Martin Livermore is the Director of The Scientific Alliance