The growth of China’s cities is increasing wealth in the country, but it's coming at a cost. The economic boom is forcing farmers to move aside and make room for city dwellers.

Professor Xuemei Bai is investigating the impact of China’s unprecedented rate of urbanisation on the agriculture sector, the economy and the environment. Using data from around 200 cities, Bai is examining how urban development and economic growth have changed over the past decade and the relationship between the two.

“Between 1997 and 2006 more than 12,000 km² of land was converted into high density urban areas in China,” says Bai. However, despite this rapid development there has been a long standing debate about whether urban growth causes economic growth. “In the study we conducted, we found that there is a strong positive relationship between urban expansion and the economic growth of China’s cities. There is a causality loop between the two:  urbanisation increases GDP, which then creates pressure to urbanise, and so on,” Bai explains.

Bai’s study also showed that most of the land used for urban expansion in China comes from agricultural areas. The ratio of arable land per capita in China is already below the world average, leading to concerns about food security. These concerns are multiplied as cities continue to expand.

 “In recent years the Chinese government has started tightening its control on urban expansion in an attempt to reduce the loss of agricultural land across the country,” says Bai. “Our results show that such measures will negatively impact economic growth. In fact many cities are already facing financial difficulties due to restrictions on urban expansion.”

This leaves the Chinese government with some tough decisions. According to Bai, it will be difficult for China to limit urban expansion without sacrificing economic growth. “What is needed is better understanding of the complex interactions and drivers that link urban growth, economic growth and food security, as well as a more coordinated approach to urbanisation, land use and economic policies”.

Bai continues to explore alternative pathways towards sustainable urban development in China and Asia.