Abstract
Suppose we succeed in stabilizing the buildup of greenhouse gases in the atmosphere; it won't be because of one or more grand technological fixes. It will be because we work to adjust every factor in the equation that is amenable to change. The size of the world's population, currently 6.7 billion, is clearly one of these critical factors. Who would disagree that if our species were a fraction of its current size, our climate problems would have a fraction of their current urgency?
Economist Sir Nicholas Stern calculates that “global average per-capita emissions will–as a matter of basic arithmetic–need to be around 2 tons [of carbon dioxide-equivalent] by 2050” to avoid a potentially catastrophic threshold of warming. This is comparable to India's current per-capita emissions; the global average is 7 tons, roughly the average consumption level in China. The United States averages about 25 tons of carbon dioxide per person.
As part of his calculations, Stern assumes that global population will be around 9 billion by 2050, but U.N. demographers offer projections that vary from 7.8 billion to 10.8 billion by mid-century because of uncertainties related to fertility rates. Thus, target emissions could be as low as 1.67 tons per person with a larger population or as high as 2.31 tons per person with a smaller population.
As we look for every option to limit emissions in a warming world–and considering how far we have to go–the leeway made possible by a stabilized or gradually declining world population would be significant. The problem is that few people see population growth as amenable to change–or at least not amenable to change in ways that affirm most people's core values. Yet a powerful population-altering strategy (that also happens to be a humanitarian obligation in its own right) is improving the lives and capacities of women.
Studies around the world have demonstrated a close correlation between years of schooling among women and later childbirths and smaller families. For example, World Bank authors Dina Abu-Ghaida and Stephan Klasen estimated in 2004 that with each completed year of secondary schooling, women's average fertility rates around the world are 0.3-0.5 children lower than those of peers without these levels of education. In every country that offers a range of contraceptive options and safe access to abortion–making it easier for women to decide on the timing of childbearing–the total fertility rate is two children per woman or fewer. Thus it is possible to affect population growth–and total global emissions–by improving women's access to schooling and reproductive health services around the world.
Few people see population growth as amenable to change. Yet a powerful population-altering strategy (that also happens to be a humanitarian obligation in its own right) is improving the lives and capacities of women.
Unlike emissions savings from improved energy efficiency or from replacing coal-fired power plants, those derived from slowing or reversing population growth increase with time. This is because “business-as-usual” emissions scenarios assume population growth paths that lead to 10 billion or so energy consumers in the world by the second half of the 21st century. Slower population growth would have little impact on world population during the next decade, but by the end of the century, world population could be several billion people smaller than under standard population projections. This would bring about much lower global greenhouse gas emissions than currently foreseen–with no hardship for anyone. Plus, a stable or gradually declining world population would more easily resolve other large-scale, human-caused environmental problems, from the plummeting water tables to the loss of biological diversity.
There's nothing to lose and everything to gain–including mitigating future climate change–by working to make sure that women make their own choices about their lives and their fertility.