As the IPCC's Fifth Assessment Report makes clear, we are long past the point of avoiding climate change. The best we can do now is to avoid the worst effects. The situation is more dire than previously projected and the consequences of inaction more starkly drawn than ever before:
Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased....Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent (high confidence).... Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.
In a perfect world, the IPCC's report would summon forth our best efforts at mitigating climate change and its effects. We would be doing whatever is necessary and prudent to avoid a human and environmental catastrophe. By now, however, it is evident that governments -- and the people they represent -- are shrinking from the challenge. Hope for concerted global action on any kind of meaningful scale has largely evaporated.
Instead of asking what is the most that can be done to mitigate climate change and alleviate its consequences, perhaps we should be asking, "What is the least that can be done?"
The "least" we can do is to mitigate the scale of human suffering and displacement, and the single most cost-effective means of doing so is to prevent unplanned pregnancies. Nearly 40 percent of all pregnancies in the world are unwanted or unintended, and preventing them would make a valuable contribution to climate change mitigation and adaptation.
Giving every woman the power to avoid unwanted pregnancies would dramatically lower projected population growth rates. According to the latest UN population projections, world population, currently 7.2 billion, is likely to reach 9.6 billion by mid-century and continue rising, but if the total fertility rate (i.e. the average number of children per woman) were to fall by just half a child, world population would rise to only 8.3 billion and gradually decline during the second half of the 21st century.
It's particularly important to prevent unplanned pregnancies in the United States, where our carbon footprints are, on average, nearly twice as high as they are in many European countries and twenty or more times higher than many developing countries. A study released five years ago found that the average "carbon legacy" of a child born in the U.S. would produce about 20 times more greenhouse gases than the mother or father would save by adopting a lower carbon lifestyle (i.e. driving a highly fuel efficient vehicle, using energy efficient appliances, etc.).
But even where carbon footprints are relatively small, no one should discount the contribution that birth control could make to lowering projected greenhouse gas emissions. A 2010 study of energy use and demographics by Brian C. O'Neill concluded that slowing global population growth "could provide 16-29% of the emissions reductions suggested to be necessary by 2050 to avoid dangerous climate change." That is not insignificant.
Even if preventing unplanned pregnancies in developing countries contributed absolutely nothing to reducing future greenhouse gas emissions, there is a compelling moral case to be made for expanding international family planning services and information. That's because women and children in countries like Mali, Niger, Somalia, Uganda, Bangladesh, and Ethiopia find themselves on the front lines of climate change. Subsistence farmers, in particular, are vulnerable to the crop damage that will be inflicted by heat, drought, flooding, and rising seas. Some of the most vulnerable and food insecure countries in the world -- countries that are already in a struggle for survival -- could likely see their populations double or even triple in the next half century. Denying women in these countries the ability to space and limit their pregnancies will compound the suffering that is likely to be caused by climate change. Large families in environmentally-stressed communities will be less resilient and inevitably suffer more from disease, food insecurity, and water scarcity.
Access to reproductive health services is recognized by the United Nations as a universal right, but in many parts of the developing world it is far from being a reality. Making that right a reality for women everywhere may not save the world from climate change, but it would go a substantial way toward alleviating the human suffering that will accompany it. The costs of empowering women and providing family planning services are trivial compared to the benefits that would result from giving women reproductive choice. It really is the least we can do...for climate change...and for the women and their families who will endure some of its worst effects.