The Optimum Population Trust recently published a study which claims that Britain's optimal population is about 17 million people:
If the UK had to provide for itself from its own resources, it could support a population of only 17 million – 43 million less than its latest official population figure* - according to new research by the Optimum Population Trust.
Even if the UK dramatically improved its sustainability with a 60 per cent cut in carbon emissions by 2050 - the target set by the present Government - UK “overpopulation” would grow from 43 to 50 million, the research shows. This is because projected population growth of 17 million**, taking the country’s population to 77 million by 2050, would cancel out the sustainability benefits of carbon savings.
The sustainability of human populations: How many people can live on Earth? ***, published today (Monday February 18), is based on a new analysis of biological capacity and ecological footprinting data. It suggests that in 2003, the last year for which comprehensive data are available, total world population was 6.3 billion but the sustainable figure was 5.1 billion. Global overpopulation was thus 1.2 billion. (italics in original)
A 9-page report based on this study can be downloaded here. From pages 2 to 3:
Not surprisingly, the impact of this population growth on the environment since 1750 has been extensive. Now, not a day goes by without news of droughts, floods, famines, conflicts over resources, extinctions, and, in the last 20 years, the increasingly evident effects of global warming. This impact has been expressed in what has become known as the Commoner-Ehrlich Equation:Note that it is assumed that technology is multiplicative factor that increases the human impact on the environment. Yet technology mitigates the impact we have on the environment by enabling more efficient use of resources and/or less polluting methods to be used.I = P x A x T.This states that the impact (I) on the environment is directly proportional to the population size (P), the ‘affluence’ (A) (defined as the resources a population consumes and wastes) and technology (T) through which we (1) prolong life, (2) produce things more quickly and cheaply (thus feeding back into consumerism and affluence) and (3) grow food faster which feeds back into ‘population’. This equation thus neatly summarises the impact of humankind on the planet.
It is technology that has enabled us to sustain the large population we currently have on earth, living longer and healthier than at any time in history. Remove the technology and the environment would be devastated as people desparately try to grow food and obtain water using methods that simply cannot sustain us. Indeed, based on similar points to mine above, Tim Worstall argues that we should divide by T rather than multiply. However reading further, it seems that T isn't measuring technological advancement, but rather the impact of technology on the environment:
Politicians, unsure what to do, offer solutions which include suggestions such as: develop fuel-efficient cars; change to efficient light bulbs; fly less; build renewable energy and nuclear power plant; increase mass transit systems; and plant trees. These solutions only address the reduction of the affluence and technology variables of the equation, but never the population variable.Here the paper acknowledges that technology can in fact reduce the impact of humanity on the environment (though it argues that the drive to economic growth will then cancel this out). To retain T as a multiplicative variable, whilst acknowledging that it can reduce humanity's impact on the environment, one must consider it to be a measure of the impact of our technologies on the environment, rather than a measure of advancement. Technological advancement will thus tend to reduce T, and I'd suggest it has been doing so for centuries whilst increasing population and affluence have offset the reductions in impact it enabled.
Reducing impact by decreasing affluence (consumption) only partly addresses the problem since populations are growing faster than affluence – for example, in Africa. Technology, meanwhile, tends not to “decrease” at all. Whilst it can be used to reduce the impact of affluence, it is likely that its benefits in energy saving devices will be cancelled out by its disadvantages, as businesses continue to use it to maximise their economic growth via consumerism. So, realistically, impact will continue to rise since economic growth demands it. This is bad news since, as we will now see, human impact on the planet is already unsustainable. (italics in original)
An interesting point is that there is no mention in this study of one of the main findings in demography which is that increasing affluence has lead to a fall in birth rates resulting in slow population growth rates or even declining populations in rich countries. This implies that rising affluence may in fact help with the goal of slowing population growth, a finding that is at odds with the arguments presented on the OPT's paper.
I intend to return to other aspects of this paper in later posts.