Natural selection has ensured that we are well-endowed with selfish genes. We will always put self before family, family before community, community before country. Hence efforts to get international agreement on controlling global carbon emissions will always be bedeviled by the “after you” syndrome.

The latest report of the UN population division of March 11, 2009 shows that the world's population is 6.8 billion, and is expected to exceed 9 billion by 2050.When I was born in 1930, there were only 2 billion people on Earth. What has happened to cause this staggering increase, and for how long can it continue?Back in 1972, the Club of Rome pointed out that there are indeed limits to growth, as exemplified by the finite limits to our reserves of fossil fuels. But we failed to realize that we are living under a glass ceiling that traps our carbon emissions and causes the Earth to warm up. It is an ill bird that fowls its own nest, but that is exactly what we are doing to our environment. We always used to think that the future was boundless; the sky's the limit. But it is slowly beginning to dawn on us that the phrase has acquired a sinister new meaning; today, the sky is the limit.It is human activities, whether it be the farts of our domestic cattle and sheep, or the burning of our forests, or the emissions of our power stations, or the exhausts of our cars, or the production of cement, or the cremation of our bodies at the end of our days, that are all are contributing to global warming.What can we do about it?Unfortunately, natural selection has ensured that we are well-endowed with selfish genes. We will always put self before family, family before community, community before country. Hence efforts to get international agreement on controlling global carbon emissions will always be bedeviled by the “after you” syndrome. With the Copenhagen Climate Change Conference set for December, can we expect any breakthroughs in this potential stalemate?Perhaps there is some hope. A young PhD student at the London School of Economics, Thomas Wire, has just carried out a detailed cost-benefit analysis of all the ways in which we might be able to reduce future carbon emissions. His startling conclusion is that it is family planning that is one of the cheapest ways of combating climate change. Each $US7 spent on basic family planning would reduce carbon dioxide emissions by more than one ton, so family planning must be seriously considered at Copenhagen.This fits in rather well with our own thinking. In January this year, the University of California at Berkeley hosted a two-day discussion of “The World in 2050”, with 42 participants from all around the world. The conclusion was that it was rapid population growth in some regions, combined with increasing affluence and explosive growth in fossil fuel and natural resources consumption, that was seriously endangering a broad range of natural systems that support life.The world's population is growing by 78 million this year alone, and more than 95 per cent of this growth is in low-income countries, especially in sub-Saharan Africa. There is a large unmet need for family planning, with 200 million women wishing to delay or stop the next pregnancy, and more than 100 million women not using any contraception because they have no access to it.Even in the U.S., one of the most affluent and effluent nations in the world, half of all pregnancies are unintended. There is also increasing evidence to show that rapid population growth, which produces a large number of uneducated, unemployable, testosterone-driven young men, is a recipe for civil unrest.The manuscripts from our Bixby conference in California have just been published by the Royal Society of London as a theme issue of its Philosophical Transactions – Biological Sciences, entitled “The impact of population growth on tomorrow's world”. The Royal Society has agreed to give a copy to each delegate attending the Copenhagen Climate Change Conference.If we could ensure that all the women of the world had the ability to control their own fertility, so that every birth was a wanted birth, we would no longer have a plague of people, and the world would breathe more easily in the years to come.Roger Short is professor at the faculty of medicine, dentistry and health sciences at Melbourne University.(Source: theage.com)