A team of scientists has discovered that several major cities in the United States, including Miami and New Orleans, are at risk of becoming submerged in water as a result of drastic changes in sea levels. The new report suggests that this event will most likely occur no matter what efforts are conducted to curb global warming.

In a new study published in Proceedings of the National Academy of Sciences on Monday, Oct. 12, the authors said that doing nothing to decrease fossil fuel burning up to the year 2100 will subject Earth to a sea level rise of about 14-32 feet. The big question is "when?"

Ben Strauss, lead author of the study and vice president for sea level and climate impacts at Climate Central, said that it may happen in the next 100 years or it may take centuries. He compared the idea to a chunk of ice in a warm room, which is known to eventually melt but the rate at which it will is hard to say.

In the study, the researchers pointed out to the lands at risk, where about 20 million people live. They projected carbon emissions of businesses as usual, adding to the picture the complex and irreversible melting of the ice sheet in the West Antarctic.

The authors also investigated the events that may transpire if the world would achieve peak carbon emissions by the year 2020 - an occurrence that would have to happen significantly earlier than the present goal of 2050 peak by some world powers.

Strauss said that an online tool enables people to view the effects of the natural changes in different cities in the U.S. According to the study, the tool, which will have a global version in November 2015, shows "lock-in dates" that are far above which the diffused effects of carbon emission may have put them in a prolonged sea level rise that could drown more than 50 percent of the population.

For example, Norfolk, Virginia, has a lock-in date of 2045 if carbon emissions are continuous.

At present, Miami and New Orleans have already moved past its limits.

"In our analysis, a lot of cities have futures that depend on our carbon choices," Strauss said. He added that it is difficult to picture how to protect Miami in the long term.

The situation of New Orleans is really sad as it is significantly worse compared to that of Miami.

Next in line to Florida in the most affected cities are California, Louisiana and New York.

All in all, 14 cities with over 100,000 residents prevent locking in the next 100 years; these include Sacramento and Stockton in California, Virginia Beach in Virginia and Chesapeake, Norfolk.