城市群是城市化的高级阶段，随着城市化进程的加速，人口、产业向我国东部沿海地区三大城市群集中，城市高度密集，人口众多，经济发达。本文的主要目的研究气候变暖导致的极端天气事件对我国东部沿海三大城市群的影响。本文首先分析了城市群易损程度，通过专家问卷的方法，确定各项指标的重要性，再通过层次分析法（AHP）确定相关指标的的权重，并对相应的权重进行叠加，计算不同城市的易损程度。并在ARCGIS中将城市群易损程度划分为五个等级，分析城市群易损程度的空间格局。

分析历史时期干旱、高温热浪、洪涝三种极端气象事件的时空变化特征，并采用了BCC-CSM2-MR数据集SSP1-2.6，SSP2-4.5，SSP5-8.5三种气候模式对我国未来时期( 2020—2050 年)三大城市群的气温，降水等气候要素的变化趋势进行预估，计算不同排放情景下干旱，高温热浪，洪涝等气象灾害的气象灾害危险性，基于预测的未来经济数据构建城市群易损程度，输入气候变化风险评估模型并评估我国东部三大城市群气候变化的风险。本文以“历史分析-未来预测-风险评估”的研究思路为主导，分析结果表明： 

（1）城市群易损程度方面，高易损程度主要集中于北京，天津、南京、无锡、苏州、上海、佛山、广州、深圳、东莞等一线城市和新一线城市。这些城市往往伴随着较高GDP和人口，当气象灾害来袭时承担了更高的风险。从整体上来看，三大城市群中易损程度较高的城市群是长三角地区，而京津冀城市群相比于长三角和珠三角，易损程度整体偏低，

（2）由于珠三角区域季节性的冬旱和春旱频发，因此总体上未来干旱风险最大的是京津冀城市群，其次是珠三角城市群，最后是长三角城市群。未来高温热浪风险主要取决于地理位置，空间集聚分布明显，高温热浪风险从南到北逐渐递减，并且在同一城市群位于内陆城市的高温热浪风险高于沿海城市的高温热浪风险。未来2020-2050年三大城市群洪涝的危险性集中于长江中下游地区，即长三角城市群的洪涝风险最大，而位于低纬度区域的珠三角城市群的洪涝风险居中，位于中高纬度的京津冀地区的洪涝风险最小。

（3）我国东部沿海三大城市群中气象灾害危险性最大的是珠三角城市群，其次是长三角，气象灾害危险性最小的是京津冀城市群，气候变化危险从南到北逐渐递减。且随着排放强度的增加，在高排放情景SSP5-8.5 气象灾害危险性有增大的趋势。

（4）我国东部沿海三大城市群中气候变化风险中京津冀城市群表现出良好的城市韧性。而长三角城市群的气候变化风险各有高低，区域协调性并不一致，整体风险略强于京津冀城市群。此外，珠三角城市群气候变化的风险性整体较高。从整体上看，不同排放情境下，排放强度越高，各个城市群气候变化风险性越大。

Urban agglomeration is the advanced stage of urbanization. With the acceleration of urbanization, the population and industries are concentrated in the three major urban agglomerations in the eastern coastal areas of China. The cities are highly dense, with large population and developed economy. The main purpose of this paper is to study the climate risks associated with rapid urbanization in the global context of climate change. Firstly, this paper analyzes the vulnerability degree of urban agglomeration, determines the importance of each index by means of expert questionnaire, and then determines the weight of relevant indexes by means of analytic hierarchy process (AHP). Then, the corresponding weight is superimposed to calculate the vulnerability degree of different cities. In ArcGIS, the vulnerability degree of urban agglomerations is divided into five levels to analyze the spatial pattern of vulnerability degree of urban agglomerations.

This paper analyzes the temporal and spatial variation characteristics of drought, high temperature and heat wave, flood in historical period, and uses BCC-CSM2-MR data sets to predict the change trend of temperature, precipitation and other climatic factors in the future (2020-2050) of the three urban agglomerations in China under SSP1-2.6, SSP2-4.5 and SSP5-8.5. Firstly, the meteorological disaster risk of drought, high temperature and heat wave, flood under different emission scenarios is calculated. Secondly, the vulnerability of urban agglomerations is constructed based on the predicted future economic data. Finally, this paper inputs the above results into the climate change risk assessment model and evaluate the climate change risks of the three major urban agglomerations in eastern China. This paper is based on the research idea of "historical analysis-future forecast-risk assessment". The results show that:

(1) In terms of the vulnerability degree of urban agglomerations, the high vulnerability degree is mainly concentrated in Beijing, Tianjin, Nanjing, Wuxi, Suzhou, Shanghai, Foshan, Guangzhou, Shenzhen, Dongguan and other first-tier cities and the new first-tier cities. These cities tend to have higher GDPs and populations, and bear higher risks when weather disasters strike. On the whole, the Yangtze River Delta is the most vulnerable city cluster among the three major urban agglomerations, while the Beijing-Tianjin-Hebei urban agglomeration has a lower vulnerability than the Yangtze River Delta and the Pearl River Delta.

(2) Due to the frequent occurrence of seasonal winter and spring droughts in the Pearl River Delta region, the Beijing-Tianjin-Hebei urban agglomeration is at the highest risk of drought in the future, followed by the Pearl River Delta urban agglomeration and the Yangtze River Delta urban agglomeration. The risk of high temperature and heat wave mainly depends on the geographical location, and the spatial concentration distribution is obvious. The risk of high temperature and heat wave gradually decreases from south to north, and the risk of high temperature and heat wave in inland cities is higher than that in coastal cities in the same urban agglomeration. From 2020 to 2050, the flood risk of the three major urban agglomerations will be concentrated in the middle and lower reaches of the Yangtze River, that is, the Yangtze River Delta urban agglomeration has the highest flood risk, while the Pearl River Delta urban agglomeration in the low latitude region has the middle flood risk, and the Beijing-Tianjin-Hebei region in the middle and high latitude region has the lowest flood risk.

 (3) Among the three major urban agglomerations along the eastern coast of China, the Pearl River Delta has the highest climate change risk, followed by the Yangtze River Delta. The Beijing-Tianjin-Hebei urban agglomeration has the lowest climate change risk, and the climate change risk gradually decreases from south to north. Moreover, with the increase of emission intensity, the risk of climate change in high-emission scenario SSP5-8.5 tends to increase.

(4) Among the three major urban agglomerations along the eastern coast of China, the Beijing-Tianjin-Hebei urban agglomeration shows good urban resilience. However, the climate change risk of the Yangtze River Delta urban agglomeration is different, and the regional coordination is not consistent. The overall risk is slightly higher than that of the Beijing-Tianjin-Hebei urban agglomeration. In addition, the risk of climate change in the Pearl River Delta urban agglomeration is relatively high overall. On the whole, the higher the emission intensity, the greater the risk of climate change in each urban agglomeration under different emission scenarios.