5.1. The Variation Trend of Livability
To answer the first question of whether there is a universal rule in the long-term change of livability, we map the livability change along with the development of per capita income for the three cities respectively. As shown in Figure 4
, it is interesting to find that livability of all the three cities has been experiencing an N
-curve development with their scores increasing at the beginning, then declining during the middle period, and rebounding afterward. The R2
of the fitting curves are all relatively high, ranging from 0.66 to 0.82, which ascertains a significant correlation between livability and income level.
Though a similar changing pattern was detected in all the case study cities, the level of livability and the characteristics of their three-staged development were quite different. Specifically, the livability of New York and Tokyo went up to the first peak when their per capita income reached USD (United States dollar) 33,000 and USD 10,000, respectively, while Shanghai witnessed its first turning point much earlier when the per capita income grew to USD 2500 Concerning the decline of livability, it lasted for 17 years for New York, 13 years for Tokyo, and 5 years for Shanghai. During this period, the livability of Tokyo dropped most significantly from 0.8 to 0.5, while it just slightly decreased for New York and Shanghai. In the third period, when the per capita income rose beyond a certain level (that is, USD 44,000 for New York, USD 18,000 for Tokyo, and USD 6000 for Shanghai), the livability stopped declining and has recovered since then. The fastest growth of livability was found in New York, whose score recovered from 0.40 to 0.53 at an annual rate of 3%. Both Tokyo and Shanghai witnessed a mild rebound of livability with their scores increased at an annual rate of 1.6% for Tokyo and 1.1% for Shanghai.
5.2. Factor Decomposition Analysis of Livability Change
To find out the dominant factors that shape the changing pattern of livability in the last four decades so that effective policy implications could be derived, we decomposed the change in each period, and illustrate the results in Figure 5
In New York’s case, the key factors changed over time. The slow growth period from 1972 to 1984 was known as a period of social and economic turmoil where medical treatment, education and social services were not adequately provided to citizens [47
]. Such a situation undoubtedly resulted in a decrease in the number medical institutions and schools, as well as a decrease in public park availability. However, other factors, which may not be largely influenced by the turmoil, such as SO2
emission, road density and living spaces, strongly offset the negative effects of those contributors above and turned the situation around. This may be the main reason why the overall livability gradually went up during this period. Then, in the period of slight decline from 1984 to 2001, though the social security and environment (such as the crime and traffic accident rate, SO2
concentration and CO2
emissions) showed some improvement due to the recovery of the socio-economic situation in the last decade, the disadvantages in terms of the total number and availability of medical institutions and schools still slightly drew livability back. Finally, in the steady regrowth period from 2001 to 2012, internet development, together with the decrease in the traffic accident rate and CO2
emissions, resulted in an increase in overall livability. However, in this situation New York still faced problems in terms of a lack of medical institutions and schools. In short, improving healthcare and educational conditions, sustaining the urban safety, and reducing carbon emissions continuously will be essential to further improve New York’s livability.
In Tokyo’s case, the fluctuation of livability was greater than for the other two cities. During the first stage from 1967 to 1990, the fast improvement of healthcare and amenity made the most important contribution to the rapid rise of livability. Then, in the gradual decline period from 1990 to 2003, the housing prices in Tokyo took a nose-dive and caused the collapse of housing market. Economic downturns and social unrest, in the wake of the burst of housing bubble, thus dragged livability down [48
]. During this period, high crime and traffic accident rates, poor conditions in terms of medical treatment, education and social services, and poor living standards turned out to be the responsible factors. However, from 2003 to 2012, the substantial improvement of urban safety and rapid development of telecommunication environment started to turn this situation around, which allowed the recovery of the city’s livability. Thus, for Tokyo, improving urban safety, strengthening healthcare and amenity would be the most important factors for constructing a livable city.
As a rapidly urbanizing city, the extensive construction of parks, residential buildings, and medical facilities since China’s economic reform in 1978 to 2005 have played a dominant role in contributing to the rise of livability in Shanghai. However, the decrease of healthcare facility’s availability and park area, together with an increase of CO2 emissions, worsened the livability from 2005 to 2010, though the SO2 pollution and urban crime were well controlled. In the recent years from 2010 to 2012, taking the opportunity of hosting the World Expo 2010, Shanghai government paid strong attention to the urban infrastructure development and environmental improvement. As a result, the increasing investment in parks and telecommunication, combined with further treatment of SO2 pollution strongly led to the growth of livability. Thus for Shanghai, developing healthcare facilities and constructing more parks should be given priority in the future development toward livability.
In addition to revealing the city-specific priorities in livability construction (as described in the factor decomposition analysis), some common implications can be derived from the widely existing challenges in the three cities, which can help policy-makers designing new or adjusting current strategies toward livability.
First, the level of amenities and healthcare should be maintained to a reasonable standard. According to the cask theory, whereby the capacity of a cask is dependent on the shortest wood plate, the availability of medical and educational institutions under the health and amenities categories, respectively, can be regarded as the shortest wood plate in all the three cities, and there is an urgent need for improvement. The decrease in the amenity and health levels was usually caused by the more rapid growth of the urban population than of infrastructures. Thus, at the same time, constructing more infrastructure to control the urban population within a reasonable scale is also important. In the future (until 2050), over 67% of the world population will reside in urbanized areas, and most of the net increase in urban residents is expected to occur in the urbanized regions of emerging economies and developing countries, such as China, India, Mexico, and Brazil [49
]. Instead of blocking people out of mega cities, developing urban clusters and encouraging the movement of a certain proportion of population to those adjacent cities would be helpful to improving the livability of the whole region.
Second, the governance of the environment is indispensable, since it is the premise for realizing livability. In addition to the control of local pollutants such as SO2
, wastewater, and solid waste, greater attention should be also paid to the reduction of carbon emissions because (1) CO2
emissions have profound impacts on global ecosystem and environmental justice [50
]; (2) CO2
emissions in all the case study cities are huge and still increasing rapidly [51
]; and (3) CO2
mitigation is a common task for all the cities in the world as cities have contributed to over 70% of global carbon emissions [53
]. Due to the important role that cities play in global environment, many cities have set explicit targets to reduce carbon emissions in their future planning, for example, New York has planned to reduce carbon emissions by 30% by 2030, as compared to the level in 2005 [34
]. Tokyo has set a target of 25% reduction by 2025, relative to 1990 [33
]. Moreover, as has been pointed out by many studies, the efforts made to reduce CO2
emissions will simultaneously reduce many other air pollutants such as PM10
(particles on the order of 10 micrometers or less), SO2
]. Thus, the transition toward a low-carbon city can mitigate the impacts on both the local and the global environment, and should be given priority in the future city planning and development.
The case studies based on three cities could be regarded as a supplement to the knowledge on livability. There are also several potential improvements that can be pursued in the future studies. First, due to the availability of data in the officially published statistical yearbooks, only ten indicators under the five most important categories of livability were considered in this study. Results would be more accurate if more indicators regarding some common urban problems and future trends, such as air and water pollution, traffic congestion, unemployment rates, technological innovations (especially the emerging concept of smart cities), and environmental justice, could be added to the assessment framework. Although these long-term data are not always easily available, it may be possible to obtain such information through other sources, such as specialized research reports, papers, dissertations, and surveys on relevant administrative departments. Second, the N-curve development rule of livability would be more convincing if our livability assessment method could be applied to more case cities covering developed and developing countries. Third, if the policy-makers could include the long-term livability evaluation before and after their decision-making process, they could not only identify the priorities in the livability construction, but also make proper adjustments to their decisions in a timely manner. Nevertheless, though our policy implications might be helpful for strategic planning, especially in identifying the most urgently needed and underlying aspects of livability, how to proceed in practice needs extra efforts. Mere academic research is not enough. Field surveys and interviews of various stakeholders, such as local residents, enterprises, city planners, and government officers, are strongly needed to make the general policy suggestions effective and practical.