Ocean at the Door: New Homes and the Rising Sea

July 2019

In 2012, Hurricane Sandy slammed into New Jersey, producing a major storm surge and damaging or destroying many thousands of homes. In the years that followed, builders put up new houses and reconstructed damaged ones—in many areas that will be vulnerable to more flooding in the future. The post-Sandy rebuilding was a striking example of a broader pattern. Across the United States, coastal communities have recently built tens of thousands of houses in areas at risk of future flooding driven by sea level rise from climate change. That has put homeowners, renters, and investors in danger of steep personal and financial losses in the years ahead.

In 2018, Climate Central and Zillow produced the first nationwide analysis of the number of new homes in areas vulnerable to coastal flooding in all 24 coastal states and the District of Columbia. This research projected how many homes will become exposed to on-average annual ocean flooding in the coming decades—depending on what choices the world makes around greenhouse-gas pollution today. This report improves those results by incorporating full home footprint data instead of point location estimates (see methodology), and also provides results for bigger floods, in addition to annual ones.

The results are clear. If the world makes moderate cuts to greenhouse-gas pollution—roughly in line with the Paris agreement on climate, whose targets the international community is not on track to meet—some 17,800 existing homes built after 2009 will by the year 2050 risk inundation by a ten-year flood. The figures for 2100 are more than two times higher—and more than three times higher if pollution grows unchecked.

Over the past decade, public interest in sea level rise has grown, tidal flooding has increased in many coastal communities, and global attention has coalesced around the dangers of climate change in international negotiations in Copenhagen and Paris. And yet in the years after the 2009 Copenhagen meeting, the percentage growth rate at which new homes were added inside of America’s ten-percent flood-risk zones outpaced the percentage growth rate outside of those areas—in a third of the country’s coastal states.