Climate change: Kolkata, Mumbai to be most vulnerable in 50 years

Population rise and urbanisation will make Kolkata and Mumbai two of the most vulnerable cities to climate change by 2070. The two metros are rated at the top of a global ranking of cities vulnerable to rising sea levels, according to a new study released on 16 May.

Sea level rise is caused by global warming, which melts ice at the Arctic Ocean and Antarctica and it will definitely happen happen despite our best efforts at reigning in warming. If global temperatures rise to 2 degrees Celsius by 2100 - the goal of the recently signed global Paris Agreement on climate change - there will still be about 79 centimetres of sea level rise.

Sea level rise directly causes flooding, but it also makes areas more vulnerable to facing storms - such as typhoon Haiyan that hit Philippines in 2013.

Overall, more than a billion people will be at risk because of flooding of coastal cities, the study released by the ChristianAid charity said. The study combines projections of how much sea levels will rise with population growth estimates.

The report says that with a projected population of 14 million by 2070, Kolkata is the most vulnerable city in the world to such coastal flooding. The second most vulnerable is Mumbai, with an estimated population of 11.4 million. Bangladesh's capital Dhaka, China's Guangzhou and Vietman's Ho Chi Minh figure below, as do Shanghai and Bangkok. American city Miami is ninth on the list, while New York is the 17th most vulnerable.

"Ironically the three countries with the cities likely to suffer the most from coastal climate change are three of the biggest emitters of greenhouse gases. Today's two biggest emitters, China and the US, are set to take a financial hammering because of the value of exposed property, business, investment and other assets. India, currently fourth and rapidly increasing its carbon pollution, is likely to bear the brunt of the human cost," the report said.