The population explosion in poor countries will contribute little to climate change and is a dangerous distraction from the main problem of over-consumption in rich nations, a study has found.

It challenges claims by leading environmentalists, including Sir David Attenborough and Jonathon Porritt, that strict birth control is needed to reduce greenhouse gas emissions.

The study concludes that spending billions of pounds of aid on contraception in the developing world will not benefit the climate because poor countries have such low emissions. It says that Britain and other Western countries should instead focus on reducing consumption of goods, services and energy among their own populations.

David Satterthwaite, of the International Institute for Environment and Development , a think-tank based in London, analysed changes in population and greenhouse gas emissions for all countries between 1980 and 2005.

He found that sub-Saharan Africa had 18.5 per cent of the world’s population growth and only 2.4 per cent of the growth in carbon dioxide emissions. The United States had 3.4 per cent of the world’s population growth but 12.6 per cent of the growth in carbon dioxide emissions.

China’s one-child rule had resulted in a sharp decline in population growth but its CO2 emissions had risen very rapidly — 44.5 per cent of the growth in global emissions — largely because of the increasing number of Chinese enjoying Western levels of consumption.

Dr Satterthwaite, whose study is published in the peer-reviewed journal Environment and Urbanization, said: “A child born into a very poor African household who during their life never escapes from poverty contributes very little to climate change, especially if they die young, as many do. A child born into a wealthy household in North America or Europe and who enjoys a full life and a high-consumption lifestyle contributes far more — thousands or even tens of thousands of times more.”

The world’s population has risen from 2.5 billion in 1950 to 6.8 billion. It is growing by 75 million a year and is almost certain to exceed 9 billion by 2050. Nine of the ten countries with the highest predicted growth rates up to 2050 are in Africa. Uganda’s population is expected to treble from 33 million to 91 million.

The populations of developed countries, including Japan and Russia, are expected to decline over the same period.

A separate study by the Princeton Environmental Institute found that the world’s richest half billion people accounted for 7 per cent of the world’s population but 50 per cent of emissions. The difference in emissions levels between a rich Westerner and a poor African was illustrated in a study this month by the New Economics Foundation.

It found that by 7pm on January 4, a typical person in Britain would have generated the same amount of carbon emissions that someone in Tanzania would be responsible for in the whole year. A US citizen would reach the same point by 4am on January 2.

Last month the Optimum Population Trust called for population restraint policies to be adopted by every world state to combat climate change. The call was endorsed by Sir David Attenborough, James Lovelock and Jonathon Porritt.

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