A study from the Futures Group said it would cost $3.7 billion a year to provide such services to countries that don't yet have them. The public-health benefits of reducing unplanned pregnancies are clear for both mother and child, especially in high-risk impoverished areas.
A 2010 study published in the Proceedings of the National Academy of the Sciences looked at the link between policies that help women plan pregnancies and family size and global emissions (the study also looked at aging and urbanization trends). The researchers predicted that lower population growth could provide benefits equivalent to between 16 and 29 percent of the emissions reduction needed to avoid a 2 degrees Celsius warming by 2050, the warning line set by international scientists.
But the benefits also come through easing the reduced resources that could result from climate change. The U.N. IPCC report notes the potential for climate-related food shortages, with fish catches falling anywhere from 40 to 60 percent and wheat and maize taking a hit, as well as extreme droughts. With resources already stretched in some areas, the IPCC laid out the potential for famine, water shortages and pestilence.
Still, the link remains a "very sensitive topic," said Karen Hardee, director of the Evidence Project at the nonprofit Population Council.
"At the global policy level you can't touch population … but what's been heartening is that over the last few years it's not just us, but people from the countries themselves talking about this," Hardee said.
Hardee conducted a review of 41 National Adaptation Programs of Action (the vulnerability documents required of low-income nations by the U.N.) and found that 37 mentioned population as a climate-related problem. Of those, six recognized family planning as a possible mitigation technique.
But none had funding for family-planning programs. And inclusion in a country-level plan doesn't translate to discussion at the international level, which is where the researchers say policy needs to be taking hold.
The very idea of intervention has even gotten some recent pushback. A study published this month from two researchers at Australia's University of Adelaide also cast doubt on whether population control could even stem growth, projecting that even drastic measures like a one-child policy would result in a population between 5 and 10 billion by century's end.
But the members of the Woodrow Wilson Center working group—which includes members from the WorldWatch Institute and USAID, as well as climate scientists—say their work can make waves, especially as world leaders prepare to meet for the U.N. climate summit in Paris next year. With countries already engaged on family planning, they say it's just a small leap to tie environmental concerns together.
"We want to achieve agreement on what the climate commitments are from individual countries," said Alexander Ochs of the Worldwatch Institute. "There's a new opportunity here, a new approach that takes a bottom-up look at what countries want to bring to the table. … We're just focused now on getting over the stumbling blocks."