Rapid world population growth must be halted to stop mankind "swamping the planet" like a "virus", a British MEP has warned.
The world's population is predicted to hit eight billion within 30 years
Liberal Democrat Chris Davies told the BBC that politicians had to break a "taboo" and discuss the subject.
The North West England MEP added that families should be encouraged to have no more than one child in an effort to combat climate change.
But he said he did not support "Chinese-like ideas of compulsion".
The comments come after the Office for National Statistics predicted last month that the number of people in the UK would increase by 4.4 million to 65 million by 2016.
The world's population is expected to reach eight billion within about 30 years.
Mr Davies, former leader of the Lib Dem group in Brussels, said: "There were 2.7 billion people in the world when I was born in 1954.
"Since then that number has more than doubled. If I make it to the age of 80 the population will have reached eight billion and will still be growing rapidly.
"While every individual should be cherished, mankind's reproduction is akin to the replication of a virus. We are swamping the planet and devouring its resources."
Mr Davies said population growth in wealthy countries like the UK and US - with their high energy and goods consumption - would have a "huge impact" on the environment.
He said: "Each addition to the UK population will release 744 tonnes of carbon dioxide during their lifetime, the equivalent of 620 return flights from Manchester to New York."
Population growth was often linked to poverty and religious bans on contraception, Mr Davies said.
He agued that family planning advice should be made more widely available, but added: "I cannot support Chinese-like ideas of compulsion to restrict family sizes.
"But political parties can no longer afford to avoid debate about population policy and the need to explore measures that might encourage smaller families."
Mr Davies said there were "many questions" on the best way to restrict population increase, adding that he was keen not to "penalise" families by taxing couples for having more than one child.
He added: "I'm happy for someone to come up with some ideas. That would at least be the first stage in a debate on the issue."