The number of people on the planet is growing, with global population approaching 7 billion. UN projections indicate that the world's population could reach approximately 9.3 billion by 2050 and 10.1 billion by 2100 – higher levels of human population than ever before. It is crucial to note, however, that average fertility has dropped dramatically over the past few decades – in most parts of the world, women today are having approximately half the number of children of women fifty years ago. The main reason that population continues to grow despite much lower fertility rates across the globe is that there is currently a large number of people of reproductive age.
Population dynamics are a relevant consideration for both climate change mitigation and adaptation. Although population growth is sometimes cited as one of the leading causes of climate change, it is incorrect to assume a direct correlation between growth in global population and growth in global emissions. Certainly, population growth has bearing on global emissions and is also likely to exacerbate other social and environmental pressures, such as food insecurity. However, what is of crucial relevance from an emissions perspective is population dynamics and composition – factors such as age, household size, level of urbanization and level of development. These factors also influence consumption patterns within populations. Ultimately, it is the level and type of consumption, rather than number of people and population growth per se, that increases emissions and contributes to climate change (Satterthwaite, 2010).
Per capita emissions in the countries with high population growth are generally far below those of most industrialized countries. For example, per capita CO2 emissions in 2007 were 19.0 tonnes for Australia (a developed country with low fertility) compared to just 0.3 tonnes for Kenya (a developing country with high fertility). Many high-emitting countries are exhibiting low or no population growth, meaning that policies aimed at population control will not address the primary source of climate change (greenhouse gas emissions from developed countries).
In terms of adaptation, what these population growth trends mean is that more people are going to be exposed to climate impacts – mainly in low-income developing countries.
Female fertility and sexual and reproductive health (in addition to many other factors) clearly have connotations for population levels and growth, and family planning programs tend to primarily target women. The UNFPA reports that there are over 200 million women in the world who are unable to use safe and effective family planning methods, despite having the desire to do so.
Gender is an important factor to consider when focusing on demographics and population dynamics to inform climate change policy. For example, women are exposed to different risks from climate impacts, and have been shown to have different consumption and lifestyle patterns to men.
The relationship between population dynamics, population growth and climate change is a complex one. Care must be taken when drawing conclusions about the connection between climate change and population growth, and the way population is subsequently used to inform climate change responses. Population growth is not of itself a key driver of climate change, and linking climate change and population growth too closely can detract from the main task of reducing emissions in developed and rapidly developing countries. In particular, the transfer of responsibility for mitigation from developed to developing countries must be avoided.
All women should have access to family planning, but this should not be treated or re-framed as a climate change solution. The health, wellbeing and rights of women should be at the core of all family planning programs. Having said that, increased access to family planning and reproductive health services could present multiple benefits, such as improved choice and health outcomes for women, and, where this leads to slower or no population growth, reduced social and environmental pressures – particularly for people in developing countries, where the impacts of climate change will be most keenly felt.
Further demographic research that takes gender into account is required to enhance our understanding of the way different population dynamics influence climate change causes, risks and responses.