Millions of Americans in low-lying coastal cities could see more flooding in coming years as rising temperatures drive up sea levels, according to a new study.

The study, conducted by Climate Central, a research group in New Jersey, examined areas that lie within three feet of high tide, where some 3.7 million Americans live. Flooding will become more frequent in those areas as mounting temperatures pour more melted ice into the ocean and cause warmer water to expand, the researchers predicted.

Slowly-Rising Seas

Sea level rise is like an invisible tsunami, building force while we do almost nothing, Benjamin H. Strauss, one of the scientists who worked on a summary of the research, told the New York Times. We have a closing window of time to prevent the worst by preparing for higher seas.

Florida would be most at risk, particularly its low-lying Southeastern portion, Strauss told the Associated Press. More than 500 U.S. cities, however, would see at least 10 percent of their residents at increased risk of flooding, including 141,000 New York City residents. In New Orleans, about 284,000 residents, the most of any city, would be vulnerable.

While scientists generally agree temperatures have been rising steadily for years, climate change skeptics deny any link to human activity, citing instead natural fluctuations. Myron Ebell, a researcher at the Competitive Enterprise Institute, a nonprofit public policy organization in Washington, told the  New York Times that as a society, we could waste a fair amount of money on preparing for sea level rise. Meanwhile, prominent Republicans like presidential candidate Rick Santorum have criticized policies to limit the effects of climate change.

Santorum Questions U.S. Impact On Climate

This debate is about whether human activity plays a role, and whether U.S. emissions cuts can have any effect when China and India refuse to go along, Santorum wrote in a recent op-ed. The apostles of this pseudo-religion believe that America and its people are the source of the earth's temperature. I do not.

While politicians grapple with the issue, insurance companies in 2011 that saw the costs of natural disasters climb to record levels have been more blunt. Industry representatives recently joined Sens. Bernie Sanders, I-Vt., and Sheldon Whitehouse,D-R.I., to discuss the repercussions of climate change.

A warming climate will only add to this trend of increasing losses, which is why action is needed now, Mark Way, head of Swiss Reinsurance Company Ltd.'s sustainability and climate change activities in the Americas, said at the time.

Since insurance companies generally don't cover flood damage, the cost of increased flooding could be passed along to taxpayers via the federal National Flood Insurance Program.