People living in cities. Percentage of World Population and Total
January 26, 2011
Where would Al Gore want China’s new urbanites to live? – Matthew Kahn. More than half of the world’s population now lives in cities, and cities are growing by three million people each week. This rapid urbanization places enormous pressure on cities to expand and improve access to basic services for their residents. As they grow quickly, cities are also struggling to grow sustainably.
Business-as-usual urbanization will entail enormous increases in greenhouse gas (GHG) emissions, which contribute to climate change. GHG emissions will undoubtedly increase in developing countries that currently have very low emissions, but planning now for sustainable development can ensure ‘greener’ growth. China is one country that is actively exploring how best to move toward greener cities.
Kahn has evidence of how environmental degradation starts to decline while incomes continue to rise with data from 35 Chinese cities where real estate prices are higher in locations with cleaner air and higher proximity to rail transit. |Matthew Kahn, urban Economist, UCLA
In China, slightly less than half the people live in cities (42% according to the UN), but urbanization is clipping along at 2.7% (2005-2010). Chinese cities will grow by many millions in the coming decades. With urbanization comes major lifestyle changes that often significantly increase GHG emissions. Not surprisingly, myriad green-city initiatives are underway in China.
Matthew Kahn, an urban economist at UCLA, spoke about China’s Green Cities at the World Bank (Watch the video). Kahn recently compared household GHG emissions for 74 cities in China, (with colleagues Siqi Zheng, Rui Wang, and Edward L. Glaeser) and the New York Times put together a list of the greenest cities and the brownest—based on household emissions.
The average winter temperature of a city is negatively correlated with a city’s household GHG emissions. This suggests that emission trends will vary depending on whether more Chinese urban migrants settle in the colder, northern cities, or in the warmer south.
In the study, even in the ‘dirtiest city’ (Daqing), a typical household produces only one-fifth of the emissions produced in America’s ‘greenest’ city (San Diego). Undoubtedly emissions will continue to rise as China urbanizes. While GHG emissions and GDP are growing in tandem, some Chinese cities may also be reaching a turning point at which environmental degradation starts to decline while income continues to rise. Kahn provides evidence for this with data from 35 Chinese cities in which real estate prices are higher in neighborhoods with cleaner air and higher proximity to rail transit.
As outlined in the World Bank’s recent Cities and Climate Change paper, the second most important factor to GHG emissions from cities, after per capita GDP, is density. Even though China has some of the densest cities in the world (see graph above) and very low per capita emissions, continuing to encourage density across all of its large and medium-sized cities is one of the most promising strategies for minimizing per capita GHG emissions.
For China specifically, the World Bank China team is in the final stages of preparing a book on Low-Carbon Cities for the Government of China. This work compiles World Bank experience on low-carbon cities including urban planning, transport and energy.
Further on green cities, the Urban Development department is launching a new Knowledge Platform on Urbanization, which includes a pillar focused on green cities. The video describes the Urbanization Knowledge Platform, which convenes internal and external experts on urbanization. For green cities, the Knowledge Platform asks how we can mitigate environmental costs during urban growth and transform cities from congested polluters into compact centers of sustainability.