Twenty mega cities of the world, including Dhaka, Chittagong and Khulna are more exposed to severe flooding and super-storm but less equipped to deal with such threats, said a study.
The Organisation for Economic Cooperation and Development (OECD) study identified 20 port cities which, in terms of population, would be the most exposed to coastal flooding by 2070s.
Fifteen of the cities are in Asia, with the first eight places going to Kolkata, Mumbai, Dhaka, Guangzhou, Ho Chi Minh City, Shanghai, Bangkok and Yangon.
The other seven cities are Haiphong (10th), Tianjin (12th), Khulna (13th), Ningbo in China (14th), Chittagong (18th), Tokyo (19th), and Jakarta (20th).
The remaining five cities are Miami (9th), Alexandria in Egypt (11th), Lagos (15th), Abidjan in Ivory Coast (16th), and New York (17th), said the study titled "The Exposure of Port Cities to Flooding: A Comparative Global Analysis".
This global screening study of the Paris-based organisation makes a first estimate of the exposure of the world's large port cities to coastal flooding because of storm surge and damage due to high winds.
It also investigates how climate change is likely to impact each port city's exposure to coastal flooding by the 2070s, alongside subsidence and population growth and urbanisation.
The assessment provides a much more comprehensive analysis than earlier studies, focusing on the 136 port cities around the world that have more than one million inhabitants.
"These cities are undergoing very rapid expansion and they are not only exposed to sea-level rise, they are also exposed to tropical cyclones," Bob Ward, director of policy at the Grantham Research Institute on Climate Change and the Environment in London, was quoted in the executive summary of the report as saying.
"It's clear there isn't any urban planning going on, and they have a lot of poor people living in very low-quality housing who are going to be especially vulnerable and exposed," he said.
Awareness of the risks and good governance is the key to diminishing the threat, said Ashvin Dayal, head of the Rockefeller Foundation in Asia, which supports strengthening of the region's climate defences.
Experts at a programme in Paris on October 30 said the hammer that dealt blow to New York by super-storm Sandy should raise the alarm for coastal mega-cities in Asia.