近期科学家研究发现，一些北美和亚洲的城市将面临严重海岸洪灾的危险。如果2050年海平面上升至预计水平，包括纽约、迈阿密、新奥尔良、波士顿在内的美国城市都将遭受严重的洪水灾害。

　　New York, Boston, Mumbai and Bangkok are among cities facing the 'highest risk' of flooding by 2050 as sea levels rise

　　Scientists warned five U.S. cities are predicted to be among the most susceptible to coastal flooding in the world

　　The University of Southampton researchers warned the yearly global cost of repairing damage caused by coastal foods could top $1 trillion in 2050

　　The most vulnerable city in the world is Guangzhou in China, study found

　　Some of the U.S. and Asia's largest cities are predicted to be among the most susceptible to coastal flooding in the world, scientists have warned.

　　Researchers say that New York, Miami, New Orleans and Boston in the U.S. are all among the top 20 cities at the highest risk of coastal flooding and could all find themselves facing extensive and frequent flood damage if sea levels rise to predicted levels by 2050.

　　Even if sea levels rose to the best-case scenarios predicted by scientists, the yearly global cost of repairing damage caused by coastal foods could top $1 trillion, according to the study.

　　A team at the University of Southampton looked at 136 coastal cities with more than 1 million residents as well as the population distribution, types of flood protection in place and elevation of storms.

　　To compile the top 20 list, they combined data about the cities with sea level predictions for 2050, plus economic and population forecasts to calculate the cost of the damage based upon the depth of water that could cover a city.

　　In the best and worst-case scenarios of estimating the magnitude of future flood damage across the world, the scientists said the flooding repair bill topped $1 trillion, Live Science reported.

　　According to the study published in the journal Nature Climate Change, the most vulnerable city is Guangzhou in China, with Mumbai and Kolkata in India making up the rest of the top three.

　　The vast majority of cities listed are in Asia and North America.

　　The U.S. makes up a quarter of the cities most at risk of coastal flooding in 2050 in the list of thetop 20, while China comprises one fifth and India a quarter.

　　In the U.S. Miami was listed as having the highest exposure to coastal flooding if sea levels rise.

　　The popular holiday destination was followed by New York, New Orleans, Tampa St Petersburg and Boston.

　　The study suggests the cost of flood damage could be reduced if flood mitigation infrastructure is built in the named cities.

　　Robert Nicholls, a coastal engineering professor at the University of Southampton, told LiveScience: 'If we did nothing about the risk, the flood damages in coastal cities would grow to huge amounts. So that's really not an option.'

　　The study said that if cities did bolster their flood prevention measures, such as erecting storm surge barriers, increasing the height of levees, flood-proofing buildings and converting low-lying areas to parks or fileds, the cost of damage could be lowered to around $50 billion a year.

　　Many climate change scientists have predicted that cities will be battered by increasingly fierce and frequent storms over the coming decades and some have suggested that we are already seeing the effects in storms such as Hurricane Sandy.

　　The researchers at Southampton University set out to identify the cities most at risk of coastal flooding after they realised scientists did not know which cities were most vulnerable to flash flooding, following Hurricane Katrina, which swept through the Gulf Coast in 2005.

　　Nicholls reportedly believes it is prudent for cities to put measures in place as soon as possible to prevent vast amounts of damage created by extreme weather events becoming the norm.

　　He said: 'The bottom line is it shows that flood risk is rising today — it's happening.

　　'All these cities need to be preparing for that.'

　　The research is part of an ongoing project by the Organisation for Economic Co-operation and Development (OECD) and is being led by Dr Stephane Hallegatte, from the World Bank.

　　相关介绍：

　　来自南安普敦大学的研究团队对居民人数超过一百万的136个沿海城市进行了调研，重点分析了其人口分布和防洪类型。他们结合各城市2050年预计海平面水平、经济与人口预测状况和能淹没一座城市的水量计算出洪灾损失。

　　研究表明，即使2050年海平面上升达到科学家预测的最低水平，全球每年修复洪灾损失的花费也将超过1万亿美元。

　　根据此项发表在《自然气候变化》上的研究报告，受威胁最大的三个城市分别是中国的广州、印度的孟买和加尔各答。其他面临洪灾危害的城市主要集中在亚洲和北美。

　　科学家认为，如果这些城市能够及时升级防洪措施，例如装配抵御风暴的海岸护栏、增加防洪堤和防洪建筑物高度等，或许能够减少损失至每年500亿美元。

　　“如果我们什么都不做，洪灾的损失将大得难以想象，这显然不是个明智的选择。”南安普敦大学海岸工程教授罗伯特·尼科尔斯说。