Forget snowbirds. These sunbirds are flying north. » Yale Climate Connection

For more than 50 years, Florida and other sunny Southern states have experienced a migratory pattern: an influx of snowbirds, a not-uncommon breed among northern state residents who flock to escape winter. Head south with your fellow sunbirds. But now, the opposite trend is setting in: Spurred by the escalating impacts of climate change, some sunbirds are migrating.

New research sheds light on demographic changes across the South, particularly in places already severely affected by climate change, such as Florida and Texas. Heat appears to have played a role in this northward migration, but that doesn't tell the full story—people are also moving on a smaller scale within cities, leaving neighborhoods that are subject to increasingly frequent flooding.

High temperatures drive people north

The southern United States has always been hot, making it a challenging place to live before the 1960s. For those without adequate cooling methods, high temperatures and humidity can mean fever illness or even death. But then air conditioning came along, a life-saving invention that changed the landscape. In fact, despite the warming trend caused by climate change, there are still about 3,600 fewer heat-related deaths each year due to the spread of HVAC systems.

Americans flocked south in droves because of this new indoor comfort. Snowbirds tired of the northern cold are notorious for moving to warmer climes in their golden years – but it's not just retirees. Southern counties are booming with populations of all ages and education levels.

That is, until recently.

Researchers Sylvian Leduc and Daniel J. Wilson of the Federal Reserve Bank of San Francisco studied immigration trends and found a clear signal: More and more people are moving south. The less.

Their study, “Snow Belt Migration to the Sun Belt, the End of an Era?” looked at population changes in counties experiencing extreme cold and heat. Southern communities that experienced extreme heat from the 1970s to the 2010s continued to signal growth.

But now the authors have discovered that some U.S. residents are moving away from areas with extreme heat, a change they attribute to climate change.

How hot is it?

As global temperatures continue to rise, it's no surprise that the hottest days are also increasing. Heat waves, defined as two or more days of extreme heat, are increasing almost everywhere, but in the United States, the trend is particularly pronounced in the South.

The chart above uses data from long-term weather stations monitored by NOAA.

Places like Miami, Tampa and New Orleans are not only hotter than they were in the 1960s when AC first moved to town. they are experiencing more than eight extra There are heat waves every year. Not only that, those heat waves lasted longer and The season in which they occur increases by more than 80 days.

Likewise, the number of days considered extremely cold is decreasing.

The map above plots the change in the number of unusually cold days since 1948, and finding where the increase has occurred is a veritable “Where's Waldo?” Communities with reduced extreme cold weather dominate the map.

Leduc and Wilson say the shift exacerbates the reversal of trends and sends more people north.

Their study also looked at demographics and found that changes in the population were uneven—with the most significant shift from the South among early-career, well-educated professionals and retirees. Both groups have traditionally been the most mobile. Snowbirds have long flocked south to escape the cold during their golden years, but the study found those numbers have reversed in the past 10 to 20 years.

Escape from floods

Floods are occurring more frequently as climate change causes more heavy rainfall and sea levels rise. This is leading to a major shift in how and where Americans choose to purchase property.

Forty percent of the population lives near the coast, where rising sea levels are causing flooding. While the average rise was five to eight inches, the rise was faster along the East and Gulf Coast. This means that when hurricanes threaten these areas, they can create higher, more damaging storm surges.

Sea levels in South Florida have already risen a foot and could rise another two feet by 2050, a clear example of this trend. Jeremy Porter leads climate impact research at First Street, an organization that links climate change to financial risks. Miami's tidal flooding has received so much media coverage in recent years that homebuyers have begun purposefully avoiding flood-prone neighborhoods because they see them on the news, he said.

Porter and his team took a closer look at the migration patterns of people living in flood-prone areas. Their study identified 818,000 “climate waste zones” – areas where population loss is a direct result of increased flood risks due to climate change. As a result, 3 million people have been relocated and a further 2.5 million are expected to leave areas at higher risk of flooding over the next 30 years.

This research is able to identify actions that others miss: those that take place locally. Unwilling to stay in homes that are at increasing risk of flooding due to climate change, but unable to leave the city for work or family reasons, people are moving out of flood-prone neighborhoods and staying within their own neighborhoods.

Hurricanes Ian, Helen and Milton have all wreaked havoc on parts of Florida's west coast over the past two years. Porter said this disruption could lead to more demographic changes in the near future.

“There was a rare event that happened and they don't remember any other events and people didn't react to it,” he said. “But if you get hit by one event, and then the next year you get hit by another event, and then maybe two years later you get hit by another event, people eventually get tired of it and they leave.”

Whether the effects of climate change force people from their homes due to flooding or they choose to leave their homes for a cooler future, migration patterns in the U.S. are changing — with far-reaching potential consequences for Southern communities if climate change goes unchecked .