Population control cheapest way to fight CO2?

"Each $7 spent on basic family planning would reduce CO2 emissions by more than one ton" whereas it would cost $13 for reduced deforestation, $24 to use wind technology, $51 for solar power, $93 for introducing hybrid cars and $131 electric vehicles.

http://www.chinadaily.com.cn/china/2009-12/10/content_9151129.htm