As historical leader of the U.K. Green Party, director of Friends of the Earth and of Forum for the Future, Jonathan Porritt has become the inescapable expert when it comes to media debates on the environment.

In addition to his functions as administrator of a powerful water supply and sewerage utility consortium, Wessex Water, he is a patron of the Optimum Population Trust, concerned by the impact of population growth.

As to the ills being experienced by the world population due to the state of the environment, his solution is not to call into question our consumer society, but rather to prescribe a reduction of the population by half.

During his recent interventions, Jonathon Porritt recommended the reduction of the British population from 61 to 30 million people. Not surprisingly, he is intent on promoting birth control, contraception and abortion. He assures us that his grand plan constitutes the least expensive solution to curb global warming.

Jonathon Porritt is chief adviser on environmental matters to Prince Charles and to Labour Prime Minister Gordon Brown. His theories are equally well received across the political spectrum, including by conservative opposition leader David Cameron. However, there are a number of discordant voices - even within the Green Party itself - in particular that of George Monbiot, environmentalist journalist at the Guardian. While he has no problem with the authoritarian aspect of a population reduction policy (all the more since his personal solution for combating global warming would be to introduce CO2 ration cards), Monbiot strongly opposes a policy that would deal a fatal blow to economic growth and to capitalism.

In the final analysis, global warming is of secondary importance in this debate. The central issue is the revival of malthusianism. Accordingly, and evidently with a view to reducing the British population, Jonathon Porritt recommends a ban on immigration, which has won him the praise of the Labour minister of immigration, Phil Woolas.