Rising sea levels will pose a very serious threat to Kolkata and Mumbai by 2050, according to the United Nations, PTI said. India headed a United Nations list of countries that are vulnerable to rising sea levels, with 40 million people in the country at risk in the next 34 years. The chart has been put together by United Nations for its environment report, The Global Environmental Outlook (GEO-6): Regional Assessments. Bangladesh, China and Philippines are close on the heels of India.

According to the report, the financial capital and West Bengal's centre of administration are at maximum risk from coastal flooding due to urbanisation and economic growth. The UN has predicted that the worst affected regions would be those in the Asia Pacific region, which has seven out of 10 most vulnerable countries in the list.

“Some countries, such as China, India and Thailand, are projected to face increased future exposure to extremes, especially in highly urbanised areas, as a result of rapid urbanisation and economic growth,” said the report published ahead of the UN Environment Assembly taking place in Nairobi next week.

Guangzhou and Shanghai in China, Dhaka in Bangladesh, Yangon in Myanmar, Bangkok in Thailand, and Ho Chi Minh City and Hai Phong in Vietnam have also been flagged as vulnerable to the adverse effects of rising sea levels by 2017. "Many of these cities are already exposed to coastal flooding, but have limited capacity to adapt due to their fixed location," the report said.