In the late 1950s, the southern end of the San Francisco Bay was filled with farms and pastures. But a decade later, the South Bay had become ground zero for a high-tech revolution that would eventually change the world. Apple orchards gave way to Apple Computers and a myriad of other information technology companies, and Silicon Valley was born.

In recent years, China, India, and other developing countries have tried to mimic the Silicon Valley success story, while paying little heed to the environmental impact of rapid industrial expansion. Bangalore, India, and Shenzhen, China, are two large urban areas that have become industrial boomtowns in the last 30 years, but at what cost to the environment?

To find out, two former Stanford researchers, Karen Seto and Margaret O'Mara, proposed a unique project that would bring together geographers, historians, urban planners, and Earth systems scientists to document the dramatic changes that have transformed Shenzhen, Bangalore, and Silicon Valley.

"The low-density, car-dependent urban growth patterns evident in the United States during the past half-century have spiked consumption of land, water, and fossil fuels, affecting energy and climate systems worldwide," Seto and O'Mara wrote. "Developing nations are now adopting Western-style ways of living and growth patterns measurably similar to the U.S. What does the globalization of the American suburb mean for the global environment?"

Seto and O'Mara proposed using satellite imagery, field studies, photography, and on-the-ground interviews to develop comprehensive databases and interactive maps showing the impact of urbanization over time. In 2006, their innovative proposal became reality when they were awarded an Environmental Venture Projects (EVP) grant from Stanford's Woods Institute for the Environment.

"For more than a decade, I had been studying Shenzhen, a city that has been vying to be China's next Silicon Valley," recalled Seto, a former Woods Institute fellow, now an associate professor of the urban environment at Yale University. "Margaret O'Mara is an expert on Silicon Valley, what she has called a 'city of knowledge.' In our early conversations, it became clear that some of the patterns I had observed in Shenzhen were remarkably similar to those in Silicon Valley. Margaret and I had both read about Bangalore as 'India's Silicon Valley,' so the project became a comparative study of North American patterns of urban development in Silicon Valley, Shenzhen, and Bangalore."

Satellite imagery

As a result of the EVP grant, Seto, O'Mara, and their colleagues have produced three time-series "geodatabases" graphically depicting the transformation of Silicon Valley since 1950, Shenzhen since 1972, and Bangalore since 1980. Each database contains a wealth of information on key indicators of change, including population growth, transportation infrastructure, agricultural land use, and even major shopping areas.

"All three study sites have environmental amenities-like good weather, natural resources, and green space-that make them appealing locations for international businesses and high-tech professionals to relocate," Seto said. "Prior to the development of Silicon Valley, the region was a productive agricultural center. But most of the prime agricultural land has been converted to high-tech parks and residential developments, accelerating the loss of green space. Our study shows that the same patterns hold true for Bangalore and Shenzhen."

The project also has generated new insights about the impact of rapid urbanization at the local level. "The EVP team was able to formulate narratives of the political histories of these metropolitan areas, the growing role of multinational corporations in the metropolitan landscape, and the potential pathways to sustainability that may be appropriate for each location," said O'Mara, now an assistant professor of history at the University of Washington and an affiliated scholar at Stanford's Bill Lane Center for the American West.

Much of the visual data used in the project comes from NASA's Land Remote-Sensing Satellite (Landsat) Program. The power of the Landsat imagery can be seen at the websites of two new research groups led by Seto and O'Mara that evolved from the EVP grant. Both groups include interdisciplinary research teams made up of faculty, students, and staff from Yale, Stanford, and the University of Washington. The Urban Environment Group at Yale University website offers striking satellite images of the transformation of Shenzhen over the last three decades. The Knowledge Cities Research Group  website provides detailed, interactive maps documenting changes that have occurred in all three urban areas.

"Our study reveals the usefulness of comparative investigation over space and time, and the significance of political economy to environmental change," O'Mara noted. "In all three study sites, environmental changes have been accelerated by periods of rapid increase in gross domestic product and attendant urban expansion. In the Silicon Valley of the mid-20th century, and in the Bangalore and Shenzhen of the 1990s and 2000s, economic liberalization and significant public investments resulted in cities where the speed of urbanization put extraordinary strains on infrastructure and resources, and where economic development priorities trumped sustainable urban and regional planning priorities."

Shenzhen example 

Shenzhen offers a prime example of a region where rapid growth has had a significant impact on the environment.

"In the late 1970s, the southern Chinese city of Shenzhen was a fishing village of about 20,000 people," notes the Knowledge Cities website. "Today, it is a booming metropolis of as many as 12 million. Selected in 1978 as the site of China's first post-1949 experiment with market liberalization, the special economic zone created in Shenzhen turned this largely agricultural swath of the Pearl River Delta into a hub of low-cost, export-oriented manufacturing."

In the EVP study, Seto and O'Mara found that increased motorization in Shenzhen has lead to increased emissions of sulfur dioxide and nitrogen dioxide gas, two harmful pollutants. 

In a 2007 study funded by the National Science Foundation (NSF), Seto and another research team used Landsat images to demonstrate a link between urban growth and rainfall patterns [see accompanying video]. Writing in the Journal of Climate, the researchers concluded that the rapid growth of Shenzhen since 1980 had actually caused drier winters in the Pearl River Delta. In an earlier paper, Seto and her co-workers found that urban areas in the delta had increased more than 300 percent from 1988 to 1996. The researchers compared this rapid growth with monthly temperature and precipitation data from 16 meteorological stations. Their analysis revealed a direct correlation between urbanization and decreased rainfall in the winter dry seasons.

"Primarily it is caused by the conversion of vegetated land to asphalt, roads, and buildings," Seto explained. "As a result, the soils have significantly less ability to absorb water, so in the winter months there is less moisture in the atmosphere and therefore a reduction in precipitation. We don't see the same impact in summer months, in part because the effect of the Asian monsoon masks the effect of urbanization. When cities are still relatively small, we don't see this pattern emerging. It happens when cities get very large. But that's the part that I think is alarming, because we see large-scale city development all over China and throughout the developing world."

In an effort to reach out to local and regional policymakers, the EVP team held a public forum entitled "The New Urban Landscape: Growth, Change, and Planning for the Next Silicon Valley," at Tsinghua University in Shenzhen. The researchers also have advised local Shenzhen officials on new strategies for combining economic development initiatives with more sustainable land-use practices. 

Cities and the environment

In addition to expanding their Knowledge Cities and Urban Environment research groups, Seto and O'Mara are planning to write a book based on the results of their EVP collaboration. The researchers also have been invited by Google to engage in discussions about how to use mapping and modeling software to inform policy decisions that lead to sustainable urbanization and land conservation.

"The primary goals of the EVP grant were to combine the strengths of history and modern geographic analysis to analyze land-use issues in three disparate regions," Seto said.

"The project has been hugely successful in this regard," O'Mara added. "Urban policies, past and present, have profound effects on the environment, from modes of transportation to energy consumption and carbon emissions, yet in both scholarly and policy conversations 'the environment' and 'the city' are all too often mutually exclusive categories. This study shows the deeply intertwined connections between environmental sustainability and urban form, and why meaningful steps toward different types of urban growth patterns are critical to the future economic and social success of cities worldwide."