Research On Urban Heat Wave Vulnerability Assessment Under Climate Change

It is an indisputable fact that negative impacts caused by climate changes have become more severe. The negative impacts of climate changes are mainly embodied through more frequent and more seriously extreme weather events. In recent years, actively adaptation to climate change has attracted more attentions. Identifying vulnerable components in certain system, i.e. vulnerability assessment, is a key step in climate change adaptation. Urban region suffers from the impact of heat wave frequently. Impact of heat wave on human health was the main research field in the former researches on influence of heat wave. The progress of assessing heat wave vulnerability systematically in urban region was relatively lack of and the number of papers about this subject was relatively limited. Moreover, certain problems were existed in vulnerability assessment, for instance, assessment structure was too complex, data regarding indicators was unavailable, indicators were too unilateral and the comprehensive assessment methodologies were lack of. Furthermore, the development of adaption to heat wave in China was lagged because there was no heat wave vulnerability assessment system that is suitable at national level. In this research, the assessment indicators are selected from various aspects of nature, social and economy, and then the heat wave vulnerability assessment system is developed under climate change perspective. The heat wave vulnerability is assessed in Beijing, Shanghai and Chongqing by applying the heat wave vulnerability assessment system developed in this paper, and the causes of heat wave vulnerability in these three cities are analyzed. This research aims at promoting the development of heat wave vulnerability assessment in China and providing theoretical support for adapting to heat wave in urban region. The main outputs and conclusions are as follow:1. Urban heat wave vulnerability assessment system which involves 10 indicators is selected based on the assessment criterion of exposure, sensitivity and adaptation capacity, and this assessment system is divided into target layer, criterion layer and indicator layer. The heat wave vulnerability in research regions is assessed by using this assessment system.2.Each indicator is weighed by using analytic hierarchy process(AHP) and entropy weight method. The results show that among the 10 indicators, the weights of number of hot days, urban population density, urban built-up area and share of urban visitors are the top four.3. Whether the urban area under the influence of heat wave is the most significant factor in urban vulnerability; the urban population density affects urban vulnerability significantly because higher urban population density means more anthropogenic heat is emitted; the share of urban visitors is another important factor affecting urban vulnerability because inter-annual variation of share of urban visitors is explicitly and increasing the difficulty of adapting to heat wave in urban region; patients access to hospital services timely is important for reducing urban vulnerability.4. From 2004 to 2013, the heat wave vulnerability of Beijing, located in northern China, shows a decreasing and that in Shanghai and Chongqing, both located in eastern and southern China, shows an increasing. The reason of this phenomenon is that Beijing’s adaption capacity increases significantly, but the increasing of adaption capacity in Shanghai and Chongqing is surpassed by the increasing of exposure.5. The heat wave vulnerability in Shanghai is the highest, and then followed by Chongqing and Beijing respectively. Among the three cities, the exposure in Shanghai is the highest, and then followed by Chongqing and Beijing; the adaptation capacity in Beijing is the highest, and then followed by Shanghai and Chongqing; the sensitivity in Shanghai is the highest, and then followed by Beijing and Chongqing. This demonstrates that exposure is affected by latitude and during the progress of urbanization both the sensitivity and adaption capacity are increasing.