Climate change and population, taken individually, are among the most contentious issues in public policy; bringing the two issues together is a recipe for controversy. The issues are linked, however, so we do need to find a constructive approach to talk about the connections.

For all of its complexities, the basic challenge of climate-change policy is the apparent conflict between maximizing short-term individual or national gains (increasing per capita GDP through use of cheap fossil fuel energy) and the long-term protection of shared benefits (minimizing global damages from climate change). The other dimension is fairness, as those populations that have contributed least to past emissions of greenhouse gases are most vulnerable to health and other impacts of climate change. Developing countries are therefore reluctant to limit their greenhouse gas emissions to help solve a problem that has, so far, been created elsewhere. For their part, richer countries hesitate to implement policies that they consider may harm their economic growth and competitiveness.

In some ways this is analogous to discussion of population policy. Again, there is a potential tension between the immediate rights of individuals (to control their own fertility) and a longer-term, population-level concern (that rapid population growth could potentially overstretch resources, hamper development and lay conditions for conflict).

These two issues are also closely linked. Although the major driver of greenhouse gas emissions remains the consumption patterns of richer populations, human population is also a fundamental long-term driver. However, discussing these links has often generated more heat than light. Even stating the fairly obvious fact that having more children will tend to increase an individual’s “legacy” of greenhouse gas emissions has sparked outraged reactions against perceived threats to individual freedom or faith. These tensions also play out at national level, as some have suggested that curbing population growth in developing counties would help to reduce climate change. In response, developing countries point out that per capita emissions of children born in poor countries are much lower than that in richer countries, and claim that they are being stigmatized for “profligate reproductive behaviour” as a negotiating position over greenhouse gas commitments.

Can these issues be discussed constructively? The best approach is probably to choose the least controversial entry point – identifying where human rights, health, environmental and equity objectives converge, rather than conflict. This can be framed around the fact that, in developing countries, approximately 200 million women express an unmet need for family planning services. Meeting this need is supported by the following arguments.

First, control over reproduction is an individual right, supported through international declarations, and embodied in the Millennium Development Goals. Second, it provides major public health benefits; increasing birth spacing from less than 18 to more than 36 months correlates with a two-thirds drop in childhood mortality. Third, avoiding local overpopulation increases resilience to near-term environmental and other stresses (a need identified by most of the poorest countries themselves). Fourth, over the long-term, it relieves climate change and other pressures on the global environment.

When developing this case, the order of the arguments is critically important. Individual rights come first, with the population health, local and global environmental benefits as welcome and important co-benefits. In contrast, using the need to reduce climate change as a justification for curbing the fertility of individual women at best provokes controversy and, at worst, provides a mandate to suppress individual freedoms.

Although the case for family planning services should be self-evident, it needs to be carefully constructed, and sensitively handled.

(A longer version of this article, with supporting references, was published in the Bulletin of the World Health Organization: http://www.who.int/bulletin/volumes/87/11/09-072652/en/index.html)