Projections from a new study just released says up to 13 million Americans living on the country’s coasts could be displaced by flooding caused by rising sea levels, according to a story in USA Today.

Almost half of those in danger of having to relocate to escape the rising waters live along the coasts of Florida, with a projected six million people facing the rising seas and other related hazards, according to the study.  Over one million residents in California and Louisiana are also projected to face re-location.

Study co-author Mathew E. Hauer of the University of Georgia, says there are 31 counties in the US with over 100,000 residents that would be affected by the projected sea level rise of six feet by the year 2100.  “Projections are up to three times larger than current estimates, which significantly underestimate the effect of sea-level rise in the United States,” added Hauer.

Even if the sea were to rise only half as much as projected, about three feet, still some 4.2 million American residents would be displaced.  The study authors noted they estimate the cost of the re-location to hit the $14 trillion mark.  The research shows as much as 25 percent of the population living in areas like Miami and New Orleans would be impacted by the rise if steps are not taken to minimize the conditions.

As the planet warms, ice melting at the polar extremes causes a rise in sea level, and the warming water itself adds to the increase, since warm water takes up more room than colder water.  The scientists say man-made climate change is the main driver behind the future rise in the seas.

According to eurekalert.org, this is the first study on projected sea level rise impact that used expected year 2100 population levels to assess the long-term effects of coastal flooding.  The authors say strategies to cope with the problem will be costly, and the longer we wait to implement measures to adapt, the more costly the measures will be.

The study’s findings were published in the journal Nature Climate Change on March 14.