A majority of U.S. coastal cities is at the risk of being submerged under water because of the alarming rate at which the level of sea water is rising, suggests a latest study. According to the researchers, the submersion will take place even if we continue to make efforts to reduce global warming.

According to the study published in the journal Proceedings of the National Academy of Sciences, some of the cities that are at the risk of being washed away include California, Miami, Boston, Florida, New Orleans and Long Beach.

"Some cities appear to be already lost," said study lead author Benjamin Strauss, in an interview with CBS News. "For New Orleans, there are levees, it's possible to build levees higher and stronger for some time, but that's not necessarily safe or sustainable in the long run. We've already seen what can happen when the levees break, when the sea level gets higher, the bigger the tragedy can be."

Strauss further said that if nothing is done to keep fossil fuel emission in check by 2100, then the sea level could increase by 14 to 32 feet. The impact of the drastic change in the sea level would impact almost 20 million people that live along 1,800 coastal municipalities.

During the research, Strauss calculated the “lock-in date” for each identified area under risk. The lock-in date is the year by which carbon accumulation would lead to sea level increase for each coastal area and submersion of a part of the land would take place.

According to Strauss' calculations, New York city has a lock-in date of 2095 and Florida has a lock-in date of 2025. On the other hand, Miami and New Orleans have already crossed the point from where it is impossible to save the cities from drowning.