Mumbai is among the world's cities that are vulnerable to global warming and rising sea levels, says a new study released on Wednesday.

The study, published in the journal Environment and Urbanization, listed Mumbai among cities � Tokyo, New York, Shanghai, Jakarta and Dhaka being some of the others � where millions are at risk of flooding and heavy storms.

The study puts the number of people living in threatened coastal areas � that lie at less than 33 feet above sea level -- worldwide at 634 million, and growing.

The study, said to be the first to identify the world's low-lying coastal areas, said that some 75 percent of all people living in vulnerable areas are in Asia. The five nations with the largest total population living in risky coastal areas are all in Asia: China, India, Bangladesh, Vietnam and Indonesia.

Solution will not be cheap, it says, and may involve relocating populations and erecting protective structures. Also, nations must think of halting or reducing population growth in coastal areas.

'Migration away from the zone at risk will be necessary but costly and hard to implement, so coastal settlements will also need to be modified to protect residents,' Gordon McGranahan of the International Institute for Environment and Development in London, a co-author of the study, has been quoted as saying.

The other two co-authors of the study are Deborah Balk of the City University of New York and Bridget Anderson of Columbia University.

The IIED publishes Environment and Urbanization.

Lending credence to the study is a draft copy of a report by the authoritative Intergovernmental Panel on Climate Change, which has been put out by Associated Press, and which said about 100 million people each year could be flooded by rising seas by 2080.

External links:

Environment and Urbanization

Intergovernmental Panel on Climate Change