Population growth is a major source of stress on the earth’s limits. Even though it is at the heart of sustainability problems, it is not the most helpful frame to design sustainability solutions. Population growth contributes to a wide range of sustainability problems and it complicates sustainability challenges. Population growth is part of an interconnected web of adverse impacts that have created an ecological crisis that threatens both biodiversity and human survival. The complex interrelationships between key sustainability issues are illustrated by the myriad ways that population growth is correlated with increasing greenhouse gas (GHG) emissions. These emissions exacerbate climate change which in turn compound population-related stresses.
Population pressures tax the world’s limited resources, expedite resource depletion, and drive scarcity. They contribute to deforestation and desertification, they destroy valuable habitats, and they accelerate the devastation of invaluable ecosystem services. They also add to the burden of the current generation, which as explained in the Brundtland Report, must provide resources for themselves and for future generations (Our Common Future, 1987). These issues make sustainable development both more urgent and more difficult.
More than a century ago Thomas Malthus predicted that population growth would outstrip food supply. Population growth adds to the problems and pressures associated with food production. This includes food insecurity which can result in a cascade of adverse impacts that run the gamut from disease to migration. Insufficient food supplies increase prices and make its allocation less equitable. It also drives the agricultural sector to try to squeeze as much produce as possible out of limited arable land. The pressure on agricultural technology to feed a growing population has pushed farmers to embrace unsustainable practices. For example, the reliance on farming with nitrogen fertilizers has proven to be destructive to surrounding ecosystems. Further, the nitrous oxide created by fertilizer is a potent GHG that contributes to climate change.
Overpopulation can lead to other problems like labor surpluses. It can also contribute to inequality and injustice (both social and environmental). Some have suggested that the best way to limit environmental damage is to limit population expansion. However, there are few effective policy instruments that are capable of controlling population growth. Family planning programs can work but they offer limited benefits. Direct population-control measures are not a viable option because they are restrictive and represent a level of constraint that threatens the self-determination of women and the poor.
It is important to note that it is not rising populations that is drawing down the earth’s limited resources, it is the consumption that goes along with it. Therefore, we may want to consider reframing the issue in terms of limiting consumption rather than limiting population growth. We may also want to address the structural forces beyond the control of individuals and ensure equitable access to sustainable options. While there are policy instruments and governance arrangements that can amend structural forces, modify behaviors, and shape consumer choice, such efforts will only offer minor benefits and will not address the market failure of overconsumption.
When addressing the issue of overconsumption, we need to realize that this is endemic to wealthy countries. Overconsumption in wealthy countries represents a far greater problem than growing populations in the developing world. Thus, we may benefit from approaches that focus on wealthy nations where overconsumption is rampant. This could include measures like curbing immigration to such countries.
Clearly, population pressure is more problematic in some places than in others, so we may benefit from targeted approaches that focus on problem areas and pay special attention to the people, places, and contexts where overpopulation is an issue. Thus, we should focus on urban environments and nations in the global south, especially those situated in the tropics where the ecosystems are fragile, and people are disproportionately suffering from the impacts of climate change.
Perhaps the best way to limit population growth is to address inequity and lift people out of poverty. When people can meet their basic needs, they tend to have fewer children. This could even lead to population decline like we see in Japan and much of the western world. Such a trend would make immigration more desirable. So rather than directly focus on population control, we need to improve the standard of living of people in developing countries.
This is in no way to suggest we should ignore population growth. As is evident in the U.N. Sustainable Development Goals (SDGs), population growth is a key sustainability problem. Factoring population growth is essential as it is inextricably linked to the whole gamut of sustainability challenges and it contributes to a wide range of adverse environmental impacts. In this sense population data is an essential sustainability metric that can help us to shape solutions, however, it should not be the primary frame we use to design solutions.
The circular economy provides a good example of an alternative economic paradigm the uses population statistics appropriately. Rather than focus on limiting population growth, we may be better served by the approach of the circular economy, which lifts people out of poverty and respects the limits of growth.
Our inability to directly control population growth means that we need alternative arrangements like poverty alleviation. We need to focus and broaden our view of population growth. We need to focus by zeroing in on geographical zones that will enable us to help the most vulnerable. and we need to broaden our view by looking at poverty in a global context.
If we want to trace back sustainability problems to their source, we need to look at the myopic focus on economic growth and traditional state-based metrics like GDP. Many of the problems associated with population growth can be addressed by curbing economic growth and alleviating poverty. So rather than viewing sustainability problems through the lens of population growth, we may be better able to design solutions by framing the issue as a problem rooted in inequality.