In our concern for the ecological sustainability of the planet – or some subset of it such as a nation or city – it is misleading to see the number of people as the problem. This is because the ecological impact of a person during their lifetime, in terms of the resources they use, the wastes they generate and the greenhouse-gas emissions they cause, varies so much. Although we do not have precise figures, it is likely that there is at least a 1,000-fold difference between the per person resource use and greenhouse-gas emissions of the wealthiest and poorest 1% of the world’s population.
If it were possible to calculate each person’s ecological footprint during their life in terms of, say, the freshwater, fossil fuels, agricultural land, forestry products and non-renewable resources used as a result of their consumption, again the differentials between the wealthiest and poorest groups would be very large. Indeed, for perhaps as many as 1.5 billion people, consumption levels are so low that they hardly have any ecological impact – they draw their energy from renewable resources, they do not have electricity, they make very little use of fossil-fuel powered transport and their food is mostly locally produced (including what they grow themselves) and not energy or carbon intensive.
There may actually be a significant number of people whose livelihoods reduce greenhouse-gas emissions more than their consumption contributes to it, since they are reclaiming material from wastes and the greenhouse-gas emissions saved are more than those caused by their consumption.
We get some idea of the scale of the differentials in people’s ecological footprints by comparing average figures for nations or for cities. These figures can be misleading because they hide the fact that there are low consumers in wealthy cities and nations, who bring down the averages, and high consumers in low-income nations or cities, who push them up. But the differentials are still very large. For instance, between some of the wealthiest nations and a group of the poorest nations, there is a more than 200-fold difference in greenhouse-gas emissions per person.
There is also a more than 200-fold difference between average per capita greenhouse-gas emissions in cities, as shown by an analysis from Daniel Hoornweg, Lorraine Sugar and Claudia Lorena Trejos Gomez, due to be published in the journal Environment and Urbanization. This shows that many cities in the United States have annual per capita emissions of 11 to 21 tonnes of carbon dioxide equivalent, while many European cities have three to eight tonnes. For Latin American cities, it is between one and four; for many Indian cities, between 0.7 and 1.5; and for some cities in Bangladesh and Nepal between 0.1 and 0.5.
Perhaps it is population growth that is driving the increase in greenhouse-gas emissions? Actually, the growth in emissions in recent decades has largely been caused by the increase in consumption in high-income nations, most of which had little or no population growth, while it was nations with very low emissions per person that tended to experience the highest population growth rates.
Perhaps, then, the problem of “population” is more evident at a regional rather than a global level, as the number of people is overwhelming local resource availabilities, especially agricultural land and fresh water. But there is a puzzle here too: many of the world’s poorest nations actually have among the world’s lowest densities and among the largest amounts of agricultural land per person.
Well, perhaps the problem is that the poorest people, in their desperate search for livelihoods and sustenance, are the ones driving soil degradation and deforestation. But this cannot be the case either, because the poverty of these people is a result of how little land and forests they have access to. Most soil degradation and deforestation is actually caused by commercial farming and forestry.
If, then, it is a person’s lifetime consumption patterns that define their ecological impact, how do population issues fit in? We know that the current, unsustainable levels of resource use and waste and greenhouse-gas generation have been reached as a result of the consumption patterns of middle- and upper-income groups, most of whose members are in high-income nations. So if these high consumers do not reduce the ecological impact of their consumption, there is very little ecological space left to allow those who do not have high-consumption lifestyles to come to enjoy them
If the economic success of India, China and Brazil means an increasing proportion of their populations having consumption patterns comparable to those in high-income nations, then dangerous climate change will not be averted and resource constraints will increase further – unless high-income individuals and households that currently have very large ecological footprints change and demonstrate it is possible to enjoy a very high quality of life with between a fifth and a tenth of their current ecological footprint. This could set a new standard for people who become wealthy in other nations and free the ecological space needed for the modest increases in consumption needed by most low-income groups.
What, then, for population? Is extending a high quality of life to those who currently do not enjoy one likely to increase population growth rates? Actually, it does the reverse. It is the failure of aid and development assistance to provide low-income households with the basics that has helped to keep population growth rates far higher than they otherwise would have been. After 50 years of development assistance, there are probably more people today than there were in 1960 lacking the basics – adequate diet, secure livelihood, access to good quality health care (including universally available and affordable sexual and reproductive health services), schools, good provision for water and sanitation and the rule of law, including protection from eviction from their homes.
If development assistance and the governments it supports learn to become more effective in ensuring these needs are met, population growth rates will come down much more rapidly. Lower fertility rates in themselves will not reduce pressure on the planet’s ecological systems, however; this will depend on how consumption patterns change among those who are wealthy and those who become wealthier. It is possible to have a very high quality of life with consumption that generates one to 1.5 tonnes of carbon dioxide equivalent annually. This can be seen in high-quality, high-density urban areas, where buildings are energy efficient, where there is good public transport and it is a pleasure to walk or bicycle and where individuals or households limit carbon-intensive consumption. As wealthier groups shift to this, so the necessary ecological space to accommodate the needs of the current and future population is created, bearing out Gandhi’s observation that “There is enough in the world for everybody's need, but not enough for anybody's greed.”
This is why I object to a focus on stopping population growth as the key to planetary sustainability. It moves the emphasis away from the culpability and responsibility of those of us in middle and high-income groups, in high-income nations, and a growing number in other nations that have copied our unsustainable lifestyles. And it blames “others” with growing populations – most of whose contribution to global unsustainability is a tiny fraction of our own.
David Satterthwaite is a senior fellow in the Human Settlements Group at the International Institute of Environment and Development (IIED).
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