By Richard Black
Environment Correspondent, BBC News website
Solving the Earth's environmental problems means addressing the size of its human population, says the head of the UK's Antarctic research agency.
Professor Chris Rapley argues that the current global population of six billion is unsustainably high.
Writing for the BBC News website, he says population is the "Cinderella" issue of the environmental movement.
But unless it is addressed, the welfare and quality of life of future generations will suffer, he adds.
Professor Rapley's comments come in the first of a new series of environmental opinion pieces on the BBC News website entitled The Green Room.
"If we believe that the size of the human [ecological] 'footprint' is a serious problem, and there is much evidence for this," he writes, "then a rational view would be that along with a raft of measures to reduce the footprint per person, the issue of population management must be addressed."
A number of studies suggest that humankind is consuming the Earth's resources at an unsustainably fast rate.
Even so, the issue of population is hardly ever discussed at environmental summits or raised by green lobby groups.
Professor Rapley, Director of the British Antarctic Survey, acknowledges it is a thorny question, invoking the spectre of forced population control and even eugenics.
He does not make suggestions about how the current upward trend, from the current six billion towards eight or nine billion by 2050, can be reversed.
But, he says population is one of a number of issues leading to environmental degradation of various forms, and needs a higher priority than it currently receives.
"Unless and until this changes," he writes, "summits such as [the recent climate change meeting] in Montreal which address only part of the problem will be limited to at best very modest success, with the welfare and quality of life of future generations the ineluctable casualty."