Enviromental Stewardship and Population Control

Rob suggests a 2.5 child limit is proposed by some as a lower parameter of responsible parenting.  Jonathon Porritt, the chair of England's Sustainable Development Commission, is arguing that the fight against global warming actually dictates a limit of 2 kids per couple.  

"I am unapologetic about asking people to connect up their own responsibility for their total environmental footprint and how they decide to procreate and how many children they think are appropriate,” Porritt said.

“I think we will work our way towards a position that says that having more than two children is irresponsible. It is the ghost at the table. We have all these big issues that everybody is looking at and then you don’t really hear anyone say the “p” word.”

The article continues:

Porritt, a former chairman of the Green party, says the government must improve family planning, even if it means shifting money from curing illness to increasing contraception and abortion.

He said: “We still have one of the highest rates of teenage pregnancies in Europe and we still have relatively high levels of pregnancies going to birth, often among women who are not convinced they want to become mothers.

Can anyone comment on the science he cites?  "The Optimum Population Trust, a campaign group of which Porritt is a patron, says each baby born in Britain will, during his or her lifetime, burn carbon roughly equivalent to 2½ acres of old-growth oak woodland - an area the size of Trafalgar Square."

UPDATE:  A reader pointed me to a recent First Things blog post by Stephen Barr challenging Porritt on the mathematics of the two-child family as sufficient to sustain the population.  The reader also adds:  "Of course, in addition to the numbers, there’s the issue of the nanny state (or worse) implications of government getting involved in setting goals for optimal population levels.  One need only look at China to see where that can go."