Karen Seto: Hidden Linkages between Urbanization and Food Systems: Chinese and Global Transitions

by Max Budovitch, MCP Candidate and STL Fellow

Karen Seto visited MIT on April 6, 2017, to give a talk jointly hosted by the STL Lab and the Environmental Policy and Planning Group (EPP) as part of the STL China Talk Series. Her talk was attended by approximately 35 students, faculty, and community members.

Prof. Seto started by describing what are traditionally understood as the four main drivers of carbon emissions: energy, transportation, buildings, and land (i.e., how much forest and other carbon sequestration resources have been destroyed).  Over 17 years of research, Prof. Seto has asked whether there is a uniquely “urban signal” in atmospheric CO2 curves that is otherwise not accounted for by the four main drivers.

The urgency of understanding the urban signal in climatological data and thereby gaining insight into how urbanization is contributing to climate change is clear when one considers what would happen if we stopped emitting all greenhouse gases. In fact, hypothetical scenarios show that even with a complete halt to emissions, the Earth will continue to warm due to the capacity of emissions to trap heat.

With this in mind, Prof. Seto narrowed her motivating research question to how future urbanization will affect land use, agriculture land use conversions, and food systems.

In seeking answer this question, Prof. Seto wrote a paper comparing official estimates of farmland reserves to satellite estimates of those reserves on a global scale. She found that the satellite estimates showed much more lost agricultural land than was indicated in governmental figures. However, in terms of percent change in loss, she found that there was not a one-to-one correlation between census and satellite data, which suggested the influence of local factors on incentivizing reporting of farmland conversion.

In another project, Prof. Seto predicted on a global scale the probability that any given quadrant of land would become urban by 2030. While in some countries there was a very high probability of urbanization in the immediate vicinity of existing urban centers, others (such as Turkey) showed large swaths of land that had a low to moderate probability of development. Prof. Seto inferred that the latter was due to poor policy that allows haphazard development on the urban fringe. She estimated that 20,000 American football fields of land will become urban worldwide every day until 2030.

However, while the statistic seems large, this only entails a loss of approximately two percent of the world’s cropland. Moreover, Prof. Seto’s urbanization model does not take into account gains in cropland area or productivity, which are likely to occur. Finally, the productivity of the cropland lost by 2030 is only slightly above average.

Despite these caveats, Prof. Seto found that cropland loss will be distributed very unevenly across the globe to the detriment of several regions and countries. Asia and Africa will face the worst losses, and the countries in Africa will lose some of the most productive cropland. Several countries will experience extreme cropland loss. Nigeria will lose six percent of its cropland, accounting for 12 percent of its current agriculture production. Egypt will lose 34 percent of its cropland, with a concurrent 36.5 percent loss in current production. Prof. Seto also pointed out that the loss will not only be geographically uneven, but some crops such as rice will be impacted to a greater degree than others.

Beyond the geographic impact of cropland loss, losing certain foodstuffs has a dietary and cultural impact. Prof. Seto asked in her research how the urban diet varies across different cities in China, and from where these different cities source their food. These questions relate back to the urban signal in the atmospheric CO2 curve, because the urban signal is determined by urban behavior, not sectoral factors like transport or buildings. That urban behavioral factor can be observed in part through the phenomenon of food systems.

Prof. Seto asks whether we can put together a model that shows the impact of urbanization on food behavior. She attempted to do so by creating linkages between urbanization and food system phenomena. For instance, working away from home and living on one’s own (two highly urban phenomena) lead to the prevalence of super markets and pre-prepared food suitable for individual consumption. Exposure to ideas (e.g. changing ideas of freshness and general consumer tastes) leads to over-refrigeration and packaging, which are two major contributors to the urban signal of food waste.

Prof. Seto concluded her talk by summarizing her argument that the future of the climate depends very much on the form and expansion of cities and the attendant phenomena.

Following her talk, a member of the audience asked exactly how food tastes varied between local and rural areas. Prof. Seto posited that the answer would vary from country to country depending on the diversity of food choice within urban centers. For instance, she cited the examples of India, China, and the U.S.; even in large Indian cities, the local Indian food is highly prevalent, as it is outside the cities, whereas in the U.S. one might find a verity of foods both in urban centers and rural areas. In China, there is a mix of regional and national cuisines in the cities, while the countryside is more localized.

Another audience member asked about how carbon policy that would make transportation more expensive might change Prof. Seto’s findings. She answered by pointing out that there are different types of “lock-in” to our carbon behavior. One type is institutional lock-in based on laws and rules that govern the use of fuels. The other is structural lock-in, such as how electricity is generated. And finally there is social lock-in. Prof. Seto argued that it is hard to “move the ship” when it comes to carbon behavior given these multiple layers of lock-in.