A group of prominent academics is behind controversial proposals to halve the number of people living in the UK over the next century, to help solve the environmental threat posed by the growth in the world's population. The Optimum Population Trust, made up of senior figures from academia, the media and the environmental movement, was criticised last week for suggesting that one method of reducing population levels would be drastically to cut immigration.

The idea was raised at a conference in Oxford, attended by representatives from several government departments, universities and lobby groups. A growing number of people -- including Sir David Attenborough -- believe damage to the world's natural resources can be reduced only by cutting the population.

But the OPT plan is possibly the most radical. It believes the UK must set an example to the world and reduce its population from nearly 60 million to 30 million by 2121. The group argues that, as the birthrate is already very low, the only way to do this is to all but stop immigration. Currently 171,800 more people come into the UK than leave each year.

However, critics -- some alarmed at the trust's growing respectability -- claim that immigrants to the UK have no impact on global figures or the world's environmental problems. The United Nations forecasts that world population will increase from 6.3 billion to 9 billion by 2050.
UK population is expected to rise from 59 to 62 million, but the OPT believes it will reach 71 million. Concern about destruction of the environment is nothing new, but mostly the focus has been on how to reduce the impact of each person.

The Oxford conference is a sign of the rising discussion about the total number of consumers. It is a debate that's been had before in the UK -- most recently in the 1970s when the government appointed a short-lived Minister of Population. The OPT is determined to put the subject back on the agenda and is building up a network of influence.

Patrons include the broadcaster and natural historian Professor Aubrey Manning, former UN ambassador and government adviser Sir Crispin Tickell, and Jonathan Porritt, the former head of Friends of the Earth and now chairman of the Government's Sustainable Development Commission.

One of the group's co-chairs is Professor John Guillebaud, professor of family planning at University College London, and last week's conference was jointly organised with Oxford University's Green College Centre. The guest list included five government departments, the Met Office and the Countryside Agency.

The OPT says population growth -- from 1 billion in 1830 to 2 billion in 1930 and 6 billion in 1999 -- must be reversed, mostly through greater access to contraception.

It says surveys show half of the women in poor countries would like to prevent another pregnancy, and initiatives in Thailand and Bangladesh suggest when women have access to contraception there is a sharp fall in birthrates.

But the OPT's plans for Britain clearly made some people in Oxford uneasy. At least two presenters challenged the arguments. Mike Mason, an Oxford-based environmental consultant, said immigrants came from another country, meaning there was no global increase, and many also sent money home to their families, who became more prosperous and had fewer children.
'You can't be anything but global if you're interested in climate change,' he added.