Villagers in the southern Philippines salvage the remains of their houses, after giant waves spawned by Typhoon Mitag slammed the coastal villages in end-November, leaving hundreds of families homeless. (AP)

By 2070, Calcutta will be the most vulnerable city in the world with respect to climate change and its effects, states a report released by the Organisation for Economic Cooperation and Development at the ongoing climate conference in Bali, Indonesia.

The report predicts that by 2070, about 150 million people will be exposed to coastal flooding caused by storms and damage due to high winds. About 40 million people now face the danger in cities with high exposure and vulnerability to climate extremes.

Out of the total population expected to suffer, more than 14 million hapless people may be from Calcutta — a seven times increase from the current population facing threat due to weather extremes.

The study analyses the risk of exposure of people, property and infrastructure to a 1-in-100 year flood event in over 130 key port cities worldwide. A 1-in-100 year flood event is a commonly accepted risk assessment standard.

Calcutta is followed by Mumbai, Dhaka, Guangzhou, Ho Chi Minh City, Shanghai, Bangkok and Rangoon (Myanmar) in the scale of vulnerability. Miami is in the ninth place and the only city within the top 10 from a developed country, while Hai Phong in Vietnam is ranked 10th.

In its estimate of the impact of climate change, the study assumes mean sea level rise of 0.5 meters by 2070 and takes into consideration the contributions of melting ice sheets.

Tracing the major reason for the increased coastal flood risk globally, the study identifies the unprecedented growth and development of the Asian mega-cities as the key factor.

It is not a coincidence that Greater Calcutta is currently on a development spree. New townships are coming up — Rajarhat is developing rapidly, Dankuni is on the drawing board and Baruipur is in the pipeline. Several highrises are also coming up in Calcutta, which is desperately lacking in infrastructure.

The aim of the study is to help policy-makers to understand the danger arising from climate changes and act accordingly — come up with adaptation strategies for climate extremes and understand the potential benefits of a mitigation policy.

Steps taken for mitigation will limit the coastal flood risk, the report notes. This will give the cities precious time to implement adaptation measures. Studies show that putting effective coastal defences in place can take 30 years or more.

“Adaptation will have to move to the top of the policy agenda today if it is to make a difference tomorrow,” according to an expert.

“We need climate change sensitive urban development planning with emphasis on renewable energy,” opined US energy expert Mark Ginsberg, who was recently in the city to attend various programmes, including one organised by the environment management cell of Indian Chambers of Commerce.

Are the politicians considering the dangers? It doesn’t seem so, especially with all the effort to develop coastal regions and even islands. They owe the citizens an answer.