Could Chinese cities be threatened by climate change?
In September 2012, Deborah Balk, Mark Montgomery and Zhen Liu published an interesting paper on the hazards of climate change in Asia1 . The authors argue that because of increasing urbanisation and global warming, Asian megalopolises will be threatened by natural hazards. Coastal areas are, of course, the most exposed to the dangers of global warming and the resultant sea level rise, but riverside cities and dry land regions may also face threats such as floods or, on the contrary, water shortage.
According to this study, Asian cities will be more exposed to danger in the event of floods than cities on other continents because of their higher density, their large population and their rapid development.
In China, coastal cities such as Shanghai and Tianjin are especially vulnerable to flood threats and other natural hazards. These cities have largely benefited from economic and political reforms. Millions of migrants have flocked to these coastal cities. New buildings and infrastructures have been created on coastal China, and these cities have turned into successful economic centres. However, this study shows that their inhabitants are at risk. In the case of Shanghai, the risk of flooding is due to several factors.
- The first problem is sea level rise. It has been shown that global warming can affect sea level rise, but other factors related to urbanisation may also increase the risk of sea level rise.
- The intense urbanisation China has experienced has led to a reduction of natural buffers (such as wetlands), and has accelerated land erosion.
- Shanghai, like Guangzhou, is located in a delta region. Rapid urbanization and industrialisation (construction of dams and reservoirs) along the Yangtze River has reduced the sediment load in Chinese river deltas2.
- The problem of sea level rise is intensified by the increasing weight of Shanghai. The densification of the city and the development of buildings and infrastructures have turned Shanghai into a “heavy” city built on sediment. Shanghai is not yet subsiding like Bangkok, but there is a very real risk of this happening.
- Another point that is highlighted in this study is that Asian megalopolises lack green zones. As a consequence, cities have become impermeable. In the event of storms, heavy rains or flood, water runoff can barely be absorbed.
What precautions should be taken by China to limit the dangers of flooding?
In our opinion, China should intervene at three different levels.
- First, the pollution issue needs to be seriously addressed by the Chinese central government. As climate change and global warming are partly caused by human activities and especially by carbon dioxide emissions, China should adopt cleaner and “greener” policies regarding energy, industrial production and transportation. By not taking the necessary measures, China has increased her citizens’ exposure to natural disasters, including sea level rise. Although carbon dioxide emissions per capita still have not reached Western levels, Beijing should still make a commitment to reduce its emissions and should put pressure on other countries to do likewise. It is time for China – the number two world power – to take the lead on environmental issues at the international level.
- The threat of natural hazards should be more often taken into consideration when planning construction projects. More green areas, including urban parks and preservation zones, should be created. Wetlands should be preserved, or even restored, so that they can fulfil their natural function of reservoirs to reduce the threat of flooding.
- On the local level, more investments are required in risk prevention infrastructures, such as levees.
The disaster that occurred in New Orleans in 2005 could, unfortunately, happen in many Asian cities, which are even more subject to flooding because of their rapid rate of urbanisation. Urban planning should not address only human and economic needs, but also environmental issues.
- Balk, D., Montgomery, M and Zhen L (2012, September 22nd) Urbanization and climate change hazards in Asia, Princeton Universityhttp://paa2013.princeton.edu/papers/132194, accessed Ferbruary 21st 2013
- Saito, Y., Chaimanee, N., 2, Jarupongsakul, T. & Syvitski, J. (2007). Shrinking Megadeltas in Asia: Sea-level Rise and Sediment Reduction Impacts from Case Study of the Chao Phraya Delta. National Institute of Advanced Industrial Science and Technology. http://staff.aist.go.jp/yoshiki.saito/Saito_INPRINT_2007_2.pdf, accessed February 21st 2013