The Ecological Roots of Pandemics

Lucy Best is a research associate for Asia Studies at the Council on Foreign Relations.

In 2017, scientists completed a years-long effort to uncover the origin of the SARS virus, eventually identifying its sources in samples taken from bats in Yunnan province. Their work also uncovered hundreds of viruses similar to SARS that could cross into humans. Just two years later, a virus with a 96 percent genetic match to one of those strains emerged in Wuhan as the 2019 novel coronavirus. As with SARS, scientists came to a widespread consensus that this virus resulted from a naturally occurring zoonotic outbreak, meaning that it originated in animals and jumped into humans. 

Experts have long warned of the potential for a zoonotic virus to emerge and wreak havoc on global health. As humans clear land for urbanization, agriculture, and other developmental purposes, they increasingly build into animals’ natural habitats. In the process, they come into closer contact with animals, thereby introducing themselves to new pathogens. Transport and sale of animals in these urban centers add to the genetic pool from which new pathogens can emerge and make their ways into humans. Furthermore, abnormal weather from climate change can induce animal migration, potentially bringing animals into contact with humans when they would otherwise remain separate. When all of these factors converge in an interconnected urban setting, the likelihood that an outbreak remains isolated decreases.

Reporting on COVID-19 rarely discusses the human influences, such as rapid urbanization and wildlife destruction, that can contribute to health crises. However, these issues are important because they highlight patterns that exacerbate humans’ vulnerabilities to emerging diseases. Moreover, these factors are crucial to consider in the context of developing policy options that could prevent future pandemics.

Caves like the one in Yunnan where the near-match to the 2019 coronavirus was found are a prime example of how seemingly isolated instances of habitat destruction can have far-reaching consequences. These caves consist of karst, a mixture of rocks that is mined to make cement. In Yunnan alone, cement production has topped 100,000 tons annually since 2016, requiring massive mining operations. With their habitats compromised, the bats that once lived in these caves would have sought shelter elsewhere. Most likely, they found it in the karst deposits throughout Yunnan, Guizhou, and Chongqing. Presumably, some of them even passed into the Hubei caves where multiple bat coronavirus were identified 2019, crossing paths with countless other bats and acquiring new pathogens throughout their journeys.

When you add Wuhan’s developmental trends to this situation, the potential paths for a virus to cross into humans are amplified. Wuhan has experienced massive growth in recent years. Whereas the city had 500 square kilometers of built-up urban area in 2010, this figure had increased to about 812 square kilometers by 2019. The city’s statistical records within this time period show myriad signs of economic success and higher standards of living—the improvements are evident in the square meters of living space constructed, the infrastructure investments, and the diversified energy resources. However, they also reflect how much the natural environments around Wuhan and cities like it are being altered as they grow to accommodate more people.

This is not to say that Chinese cities—or any cities—should abandon urban expansion in light of ecological risks. Urbanization has fueled China’s economic rise and improved hundreds of millions of Chinese people’s lives in turn. Instead, policymakers in China and around the world should gather data on their ecosystems and make decisions that support urban development without unduly disturbing their surrounding environments. One option is to set urban growth boundaries that limit outward expansion and direct development toward city centers. Policies such as these not only decrease the risk of new infectious diseases, but also improve daily life in cities by making them walkable, cutting commute times, and decreasing air pollution. At least 200 Chinese cities already have urban growth boundaries, but China’s persistent urban sprawl suggests that they are not having their intended effects. Research on similar measures in the United States shows that urban growth boundaries’ success is largely tied to political support and regulatory adherence, suggesting that they may require more society-wide buy-in before they can be effective.

Politicians in China and the U.S. have sought to deflect blame by promoting conspiracy theories about how the 2019 novel coronavirus emerged. Less sensationally and more scientifically, the virus’ origins most likely lie in these very governments’ longstanding negligence of environmental health. Now months into the COVID-19 pandemic, human society is well acquainted with the chaos and tragedies that public health crises bring. In the short term, we cannot prove whether habitat destruction played a role in unleashing COVID-19. Nevertheless, governments can note their agency in environmental governance and act to prevent future crises.