By 2050, an estimated 2.5 million people across the contiguous United States will be living in areas at risk from a so-called "100-year flood," according to a new analysis from Climate Central. These floods, which have a 1% chance of occurring in any given year, are expected to strike with far greater frequency in a warmer world, intensified by sea level rise and ever more powerful storm surges.
The report, based on Climate Central’s Coastal Risk Finder tool, projects that 1.4 million homes will also fall within the danger zones – a figure that lays bare the extent to which American life, property, and infrastructure are precariously perched on the water’s edge.
The culprit? Rising seas and a warming planet. “In the United States, coastal floods occur three times more often than they did 30 years ago — and both the frequency and intensity of coastal flooding are projected to increase,” the report states. If emissions follow the SSP2-4.5 pathway – a scenario assuming nations meet their current climate pledges – that increase could reach tenfold by mid-century.
Some of the country’s most populous and iconic places are directly in harm’s way. New York City tops the list, with an estimated 271,000 residents currently living in areas expected to face severe flooding by 2050. Florida and New Jersey follow closely, not just in the number of people affected, but in homes, infrastructure, and land at risk.
If emissions follow the SSP2-4.5 pathway – a scenario assuming nations meet their current climate pledges – that increase could reach tenfold by mid-century
Coastal areas in the northeast, with their dense populations, are particularly exposed. But it’s the Gulf Coast that may see some of the most widespread impacts, with its low-lying topography and some of the fastest rates of sea level rise in the country.
Yet not all residents are equally vulnerable. The report highlights a stark and growing inequality in the face of climate impacts. Nearly one-fifth – around 540,000 – of those living in high-risk flood zones are aged 65 or older, despite older adults making up just 16% of the coastal population. Florida alone is home to more than 143,000 older adults living in at-risk areas, accounting for 28% of the state’s exposed population.
The numbers are even more striking when viewed through the lens of social vulnerability. Factors such as age, income, language proficiency, and access to transportation can all affect an individual’s ability to prepare for, respond to, and recover from a flood.
“Three out of every four — 1,845,000 — Americans who live in areas at risk from a severe flood in 2050 have at least one component of risk, and one in four — 617,000 — have at least three,” the report finds. The data draws on the U.S. Census Bureau’s Community Resilience Estimates to provide granular insight into how deeply layered the vulnerability is, down to the individual Census tract.
Factors such as age, income, language proficiency, and access to transportation can all affect an individual’s ability to prepare for, respond to, and recover from a flood
This nuanced approach avoids the pitfalls of previous assessments that treated entire regions as having the same risk profile. “Risk is not only a function of how many people are exposed to a hazard but also how equipped those people are to respond,” the report explains.
Coastal Risk Finder, the tool behind the study, is the result of a year-long consultation with more than 100 government officials, community leaders, and researchers. It allows users to explore projected flood risks in their communities, from state to city level, and offers a growing database of adaptation solutions and resources tailored to each coastal region.
Still, the report underscores a hard truth: some level of sea level rise is now locked in, even if the world dramatically cuts carbon emissions. “Halting global warming and sea level rise requires rapid and sustained cuts to heat-trapping pollution. However, even under low-emission scenarios, sea levels are projected to continue rising for decades due to warming that has already occurred.”
For millions of Americans, that means preparing now for a future where the next flood might not be a once-in-a-century event, but a recurring fact of life.
