A new report is arguing that due to carbon emissions, there is nothing that can be done to save the cities of Miami and New Orleans — but with a lot of effort by world leaders, perhaps something can be done to save countless other cities and towns.

The report, “Carbon choices determine US cities committed to futures below sea level,” which was published in the Proceedings of the National Academy of Sciences, states that millions of Americans will be displaced by rising sea levels if carbon dioxide emissions are left unchecked, and it is even past the point of return for coastal cities like Miami and New Orleans, according to a Washington Post report.

Benjamin Strauss of Climate Central in Princeton, N.J., led the research team, which finds that over the coming decades and stretching into millenia, the waters will reclaim large areas of land where people now live. However, humans can limit the damage by making bold action on climate change. To prevent further destabilization of the West Antarctic ice sheet.

The world will almost certainly see sea levels rise at least 1.6 meters, or 5 feet, but if carbon emissions aren’t curbed in the coming years, the sea levels would rise an addition 2 feet, according to the report.

The research team determined that for every Celsius degree increase in temperature, there would be a corresponding rise of 2.3 meters of sea level over the next 2,000 years. The question still remains about how fast sea levels are rising, as most people would be hard pressed to be too concerned about rising sea levels 2,000 years from now compared to 50 years from now.

Obviously, much of this sea level rise wouldn’t be overnight so either way it wouldn’t be an immediate danger to people, but it does mean that millions of people could be displaced and have to move inland, according to the report. It would also mean abandoning entire cities in the process, leaving them as massive ghost towns to be swallowed up by the sea.