CIWEM Executive Director, Nick Reeves, debunks the myth that population decline is something to fear.

Three million new homes by 2016 is one of Prime Minister Gordon Brown's top priorities. That his announcement on more affordable homes coincided (in July 2007) with the worst UK floods in living memory, raised doubts about the wisdom of building on flood plain and questions about how much longer Britain can sustain a growing population living a 'me, me' consumer lifestyle without massive investment in the urban infrastructure. How bad does it have to get before we plan properly for a future in a world bent out of shape by climate change? It is self-evident that population x consumption = impact. And that much of that impact is damaging hugely to the environment and our ability to sustain ourselves begs the question: isn't it really time to have the debate that dare not speak its name and that many are keen to avoid? That is: how to manage our own fertility through population policy.

Of all the people that have ever lived around one-third are alive today. But, some good news! After 200 years or so of continuous and rapid population growth, the United Nations tells us that we're beginning to see population decline in more than 60 countries.  For the environment this is good news indeed, because recent surveys seem to indicate that those countries with relatively small populations are also the most environmentally-sustainable and socially-equitable.

For many politicians and much of big business population decline conjures up visions of collapsing markets, recession, bankrupt pension funds and the elderly in poverty, with fewer young people to look after them. The recent British census showed population falling in Scotland and parts of northern England. This spooked Scotland's politicians who committed to immigration and tax breaks to encourage couples 'to conceive for Scotland.' For me, a more rational response would have been: don't panic, let the numbers fall. It will be good for us and for the environment.

Economic collapse would only come to pass if there was a sudden, rapid decline in populations. A gradual decline is a different matter and the environmental benefits are obvious: fewer cars and houses,  more space and more wilderness supporting biodiversity. Population decline would also empower working people, raise the status of the socially-excluded, reduce inequalities and eradicate poverty. It will make the UK wealthier, not poorer, as some politician's fear. Throughout the world respected Universities are studying and promoting the benefits of gradual population decline. Sadly, this is yet to reach the political salons of Westminster (and Edinburgh)  where it is associated with economic collapse, famine and political turmoil. Politicians are yet to realise that population decline does not cause these things, but is caused by them. Failing economies have, throughout history, led people to leave in search of opportunities elsewhere. A quarter of the people of Europe's poorest country, Moldova, have emigrated since the collapse of communism. And in Africa, HIV is throwing previously prodigious population growth into reverse - just as the Black Death wiped out one-third of the population of medieval Britain. Devastating climate change eliminated the medieval colonies of Greenland and, nearer home, potato blight reduced Ireland's population from eight million to four million through famine and emigration.

In days of yore, when humanity had little control of its destiny, population fluctuated with the rise and fall of human fortunes. Good times led to population growth and bad times to a fall in numbers. Now, for the first time in our history, we are faced with a decline caused by good times and not bad times. It is affluence and not poverty that is leading to falling numbers. And if the causes are benign, what are the consequences? Well, if the fall in the number of people is slower than the natural growth in productivity (or output per person), then the economy will still grow. The number of consumers may fall, but the growth in incomes and export markets will ensure that demand stays buoyant. Nor will there be the demographic crisis some fear, with huge numbers of the elderly a burden on those of working age. The dependency ratio of workers to non-workers is virtually unaffected whether the population is growing or falling by 0.25 per cent per year.

However, a declining population will involve a gradual shift in power from the owners of capital to the owners of labour. Companies will be forced to train the unskilled, provide family-friendly policies to retain women and entice the elderly out of retirement. This dramatic effect was last seen in Britain after the Black Death and led to the collapse of feudalism. A severe shortage of labour meant that the 'peasants' could negotiate better wages and improve there lot generally. Death from disease was terrible, but for those who survived, prospects improved immeasurably.

So, imagine what life would be like in the UK with fewer people. Motorways without traffic jams, much less pollution, trains where you could always get seats, no ugly tower blocks, greener urban areas and low income families enjoying spare bedrooms, studies and playrooms. Marvellous!

Professor John Guillebaud, of The Optimum Population Trust, argues strongly, on environmental grounds alone, for allowing the population of Britain to decline naturally to 30 million - the level it was 100 years ago.  And a growing number of economists agree too. The scarcity of labour would stimulate the incentives for more efficient utilisation of resources, shifting the economic growth pattern from the 'input-driven type' to that of 'gains in efficiency'. In other words, instead of the policy to be pursued in Scotland and elsewhere, where you boost the economy (and harm the environment) through population growth, you have fewer, more skilled people working more smartly. Studies by the Organisation for Economic Co-operation and Development (OECD) show no correlation between population size and Gross Domestic Product (GDP) per capita. If big populations create wealth then China and India would have been the richest, and not the poorest, of nations. In fact the opposite is true. Low population countries such as Switzerland, Norway and Sweden are very wealthy, and Ireland, with only four million people, has a better GDP per capita than Britain. Luxembourg, by far the smallest EU country, is also by far the wealthiest.

But our political leaders like a large population. It means large armies, prestige and negotiating muscle. A Britain of just 30 million souls probably wouldn't keep its place at the top table of the developed world or its seat on the UN Security Council which, it would seem, is more important than a cleaner and greener environment, fewer cars and better homes for low-income families.

Floods, pollution, waste disposal, habitat destruction, urban degradation and many other problems will absorb a disproportionate amount of resources as the number of people increases. The quality of life, except for a minority of the rich and powerful, will decline. It is therefore desirable that we avoid this by voluntarily taking responsible action so that we achieve a sustainable global population. This is one of the biggest challenges in politics and we owe it to future generations to rise to that challenge.