In the 1970s, current Obama administration science czar Dr. John Holdren wrote a book advocating various measures to stop global starvation, including a world government and mandatory birth control.

Food is no longer an issue, science took care of that despite the protestations of Holdren and fellow doomsday prophet Professor Paul Ehrlich, so culture moved onto something new that would require social engineering and selecting who gets to give birth: global warming.

John Guillebaud, Emeritus Professor of Family Planning and Reproductive Health at University College London, writes in BMJ that it's time to implement 'voluntary' family planning, because the developing world has fertility rates ranging from 2.1 to over 5, and the population in the least developed 48 countries could triple by 2100, making their carbon footprint unsustainable.

Population control is the way to go, he writes. Simply by having one less child, an American woman would reduce her "carbon legacy" (the summed emissions of herself and her descendants weighted by relatedness) by 9441 tons, he writes. This is around 20-fold more than would be saved by other eco-actions.

He says "action on population growth as well as technology and consumption is essential to ensure that climate mayhem is both minimised and mitigated."