Climate change is predicted to exert multiple shocks—extreme heat, flooding, and drought—on food systems. This threatens food provision in urban areas, and will make the situation even more precarious for populations that are already food insecure.
But, there’s a way to soften this blow: having a geographically-diverse palate. In fact, a new study finds that cities that get their food from several different places—meaning locations with different socioeconomic and climate characteristics—are markedly more resilient to weather-related food shocks.
Using real-life data on drought and food flows from the period between 2012 and 2015 in the United States—a time when parts of the country were affected by disruptions to food supply—and exploring how that affected 284 cities, the researchers on the new Nature paper created a model to demonstrate which cities would likely cope better with future climate threats to food systems, and which would fare worse.
Their model drew on ecological theory, a principle of which is that biodiversity helps to buffer ecosystems against external threats. Using this idea, the model was designed to measure whether a diverse food supply could fundamentally reduce the intensity of a shock, which the researchers defined as the degree to which the inflow of food would be affected by the climate impact to crops and livestock.
The model revealed a very clear trend: cities that got their food from a larger array of sources were least likely to struggle with food shortages in times of shock, they found. “In other words, cities with more diverse supply chains tend to experience less disruption to their food supplies,” says Michael Gomez, a doctoral candidate in civil engineering at Penn State University, and lead author on the study.
The benefit was notable: cities that got their food from a rich array of sources were 15% more likely to be able to resist the food shortages associated with climate shocks. Reflected another way, a city with the lowest supply chain diversity could expect to experience disruption to its food supply one in every six times; meanwhile in a city with the highest rates of diversity that probability declines to one in every 202.
At the city level, resilience varied dramatically across the US. The model revealed that in general, shock intensities are likely to be greater across the western US, and lower in the east. Some of the most vulnerable to shocks were cities in Colorado and Texas, while urban areas in Florida, South Carolina, Ohio, and Virginia comparatively showed the lowest risk.
In many ways, these findings seem intuitive, because they tap into an idea we all understand: having more options gives you greater potential to respond to the unknown. But the true value of the study is that by exploring the several variables that underpin vulnerability, and then using those to actually visualize risk, it creates a model that is practically useful to cities—who can use it as a tool to see precisely where they fall on the spectrum of resilience.
Crucially, this could help them improve if they’re more at risk: “Our model could be used by city and state officials to assess the resilience of their food systems, and then use that information to develop supply chain strategies for improving resilience,” Gomez explains. “In principle, with our model cities can figure out how much they need to increase the diversity of their supply chain, in order to reduce the magnitude of a probable shock.”
This might mean local governments setting targets to achieve a baseline level of diversity in supply chains; or a city ensuring that locales usually hit hardest by food shortages have larger food inventories available, going forward. At the forefront of cities’ minds should be their most vulnerable populations, where the bulk of food insecurities are typically concentrated. Efforts to increase resilience should be crafted around the needs of these groups, the researchers write.
Ultimately, “sustainability and resilience tend to go together,” Gomez says. And as the world grows more unpredictable, we’ll need those two traits in abundance to succeed. There’s another aspect to sustainability too: environmental sustainability. Next, Gomez and his colleague will be investigating this part of the equation, he says.
“We’re currently working on combining supply chain diversity with other metrics, to look at the tradeoffs between the sustainability and resilience of food systems.”
Gomez et. al. “Supply chain diversity buffers cities against food shocks.” Nature. 2021.
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