This article is a partnership between ProPublica and The New York Times.
When Hurricane Helena, a 420-mile-wide, slow-rolling conveyor belt of wind and water, flooded parts of Florida’s coastline and then tore north through North Carolina last week, it destroyed more than just homes and bridges. It has shaken people’s faith in the security of life in the south, where losses from extreme heat, storms and rising sea levels are mounting rapidly.
Helen was just the latest in a new generation of storms that are intensifying faster and dumping more precipitation as the climate warms. Just such an event is expected to force more Americans to relocate as climate change worsens and disaster recovery costs increase.
Researchers are now evaluating tens of millions of Americans may eventually retreat from extreme heat and drought, storms and wildfires. While many Americans are still moving in high risk areastempted by air conditioning and sunny weather, the economic and physical vulnerability they face becomes increasingly apparent.
One study by the First Street Foundation, a research firm that studies climate threats to housing, found that an estimated 3.2 million Americans have already migrated, many short distances, from flood zones such as low-lying parts of Staten Island, Miami and Galveston, Texas. According to the study, an additional 7.5 million people will leave these permanently flooded areas over the next 30 years.
All this indicates a possible boom in the inner and northern cities. But it will also leave behind large tracts of coastal and other vulnerable land where the elderly and poor are likely to remain.
South of the USA waiting for a special transformation. Extreme heat, storms, and coastal flooding will weigh heavily on the bottom third of this country, making the environment less comfortable and living there more expensive and less prosperous.
The youth, the mobile and the middle class will leave more often in pursuit of opportunities and physical and economic security. This means that government – from local to federal – must now recognize their responsibility to support communities as a result of climate migration. While the aging population left behind will need more services, health care and physical accommodations, the residents who remain will live in states that may also face reduced representation in Congress — because their communities are shrinking. Local governments may be left to fend for themselves, but with an evaporating tax base to work with.
In December, the First Street Foundation created one of the first clear images how these demographic changes are unfolding. It looked at flood risk and migration patterns up to the census across the country and identified hundreds of thousands of so-called left-behind zones, where the migration of residents in response to rising risk had already passed a tipping point, and people were making small, local moves to higher ground.
The study contains many nuances — cities like Miami can continue to grow overall, even as their low-lying areas are separated. And the areas of abandonment he identified were scattered widely, including across large parts of the inland Northeast and upper Midwest. But many of them also end up in some of the very places most susceptible to storm surges from weather events like Helen: parts of low-lying coastal Florida and Texas, for example, are already seeing population declines.
In all, First Street’s report noted that 818,000 U.S. Census tracts passed the abandonment tipping point — areas with a combined population of more than 16 million people. A related peer-reviewed research component of the organization predicts that in the near futureentire counties in Florida and Central Texas may begin to decline in total population, indicating a sharp reversal of the steady growth that Florida sustained as climate pressures increased by the middle of this century.
Such predictions can turn out to be wrong – the more geographically specific such a simulation becomes, the greater its error. But the fact that climate research firms are now identifying American communities from which people may have to retreat is significant. Backing off hasn’t been part of this country’s vernacular on climate change until recently.
Other studies clarify which Americans will suffer the most. Earlier this year, Matthew Hauer, a Florida State University demographer who estimated that 13 million Americans would be displaced by sea level rise, co-authored a study that looked at what this climate-induced migration could mean for the nation’s demographics. United States, studying what it is can look like by age.
Hauer and his fellow researchers found that when some people migrate from vulnerable regions, the population that remains ages significantly. In coastal Florida and along other parts of the Gulf Coast, for example, the median age could increase by 10 years this century — much faster than without climate migration.
This aging means that older people – especially women, who tend to live longer – are very likely to face the greatest physical dangers. In fact, there is a marked overlap between the places that Hauer’s research says will become obsolete and the places that the First Street Foundation has identified as areas that people are leaving.
The exodus of young people means that these cities could enter a spiral of population death. Older residents are also more likely to retire, meaning they will contribute less to their local tax base, reducing funding for schools and infrastructure and leaving less money to cover the costs of environmental change, even as those costs rise. All this is very likely to lead to further migration.
The older these communities get, the more new problems appear. In many coastal areas, for example, one solution to rising sea levels is to raise the height of coastal homes. But as Hauer told me, “adding steps may not be the best option in areas with an aging population.” Elsewhere, older residents will be less capable and independent, increasingly relying on emergency services. Many of Helen’s victims were simply cut off this week, highlighting the dangerous gaps left by broken infrastructure and the mistaken belief that many people can fend for themselves.
In the future, authorities will need to adapt the way they maintain their services online, as well as the vehicles and boats they use to maintain communications in flooded and dangerous areas. Such consequences are alarming. But so is a broader warning inherent in Hauer’s findings: Many of the effects of climate change on American life will be subtle and unexpected. The future demographics of this country may look completely unfamiliar. It’s time to think about who might be left behind.
