With an increasing concentration of the human population in cities, it is worth asking if city-life or country-life casts more impact on the environment. It is easy to look at a pastoral farm and think that it appears wonderfully self-sufficient on the landscape and might provide all the food, water and fuel that its inhabitants would need during a catastrophic event that isolates it from the rest of the world. With more reflection, we’d see that the tractors used in the field are powered by fossil fuels, the well pump at the house is powered by electricity, and that most amenities, such as a home computer or television, were shipped from overseas. Rural folks use a lot of gasoline doing errands, such as a trip to the dentist or the grocery store.
Contrast that picture with life in Manhattan, where folks are packed into apartment buildings that share common interior walls, thus minimizing heat loss to the environment. And, many daily errands can be accomplished with a walk through the neighborhood. Of course, this is less obvious in Los Angeles, and both cities would quickly cease to function if outside deliveries of food, water, gasoline and electricity were blocked and trash was not removed. Cities function as the feed lots of modern society: they receive food, clean water, and high-quality energy from outside their boundaries, and they cast solid wastes, dirty air and water, and diffuse heat into the environment.
A new analysis by Joseph Burger and his colleagues throws some light on these comparisons. Using data from the World Bank, they found that per capita resource use is actually much higher in urban populations. Not only are there large numbers of people in cities, but the levels of income and consumption by each one is significantly higher. Urbanization does not appear to be the panacea for over-consumption of resources from the environment.
One welcome observation is that the fertility rate of humans seems to decrease with higher per capita income and energy use, potentially conferring some stability to the human population, especially in cities. Unfortunately, however, most analyses of these trends suggest that to achieve replacement fertility in the human population would require nearly a 6-fold increase in total energy use.
We will spare nature by living in cities, but for a sustainable world, we will not pull ourselves up by our own bootstraps by living in cities.
Note: This blog benefitted greatly from my discussions with Dr. Joseph R. (Robbie) Burger at Duke University
Bettencourt, L.M.A. et al. 2007. Growth, innovation, scaling and the pace of life in cities. Proceedings of the National Academy of Sciences 104: 7301-7308.
Burger, J.R., J.H. Brown, J.W. Day, T.P. Flanagan, and E.D. Roy. 2019. The central role of energy in the urban transition: global challenges for sustainability. Biophysical Economics and Resource Quality doi: 10.1007/s41247-019-0053-z
Gudipudi, R., D. Rybski, M.KB Ludeke, and J.P. Kropp. 2019. Urban emissions scaling—research insights and a way forward. Urban Analytics and City Science doi: 10.1177/2399808319825867
Moses, M.E. and J.H. Brown. 2003. Allometry of human fertility and energy use. Ecology Letters 6: 295–300