Lisa Hymas insists that providing contraception to women in the developing world is one of the simplest and most cost-effective ways to counter climate change:
Each $7 spent on basic family planning over the next four decades would reduce global CO2 emissions by more than a metric ton, while achieving that same reduction with the leading low-carbon technologies would cost a minimum of $32, according to a recent study by the London School of Economics [PDF], commissioned by the Optimum Population Trust. And if you compare contraception to the potential costs of geoengineering, the potential savings are even more massive.
She is quick to add:
I'm not talking government mandates or coercion or heavy-handed tactics -- those approaches aren't just ethically dubious, they're wholly unnecessary.