A Tulane University-led team of interdisciplinary researchers says coastal Louisiana's climate-driven land loss and population shifts could position the state to become a global leader in planning for climate adaptation.
Their findings, published in the journal Nature Sustainability , argue that Louisiana's accelerating shoreline retreat and coastal depopulation offer an opportunity to develop strategies for households, infrastructure and regional economies to adapt to climate change.
Due to global sea-level rise, many coastal populations worldwide will likely relocate inland during the next century. According to the latest report from the Intergovernmental Panel on Climate Change, Louisiana contains the most exposed coastal zone in the world, reflected in part by some of the highest rates of wetland loss. As a result, the region may offer an early preview of changes other coastal areas could face later this century.
While coastal populations globally continue to grow, Louisiana stands out as an exception. Nearly all the state's coastal zone has lost residents since 2000, particularly following major hurricanes. The researchers say this trend suggests climate-driven depopulation has already begun and may accelerate as sea-level rise increases the impact of future storm surges.
A key finding highlighted in the study involves an ancient shoreline identified by geoscientist and co-author Zhixiong Shen, now a professor at Coastal Carolina University. The shoreline formed about 125,000 years ago north of Lake Pontchartrain, roughly 30 miles north of New Orleans. At that time, global temperatures were about 0.5 to 1.5 degrees Celsius warmer than preindustrial levels, and sea levels were 10 to 20 feet higher than today.
"With global climate now almost 1.5 degrees Celsius warmer than in the mid-1800s and on track to exceed 2 degrees, we are likely already locked in for the shoreline to move that far inland," said lead author Torbjörn Törnqvist , the Vokes Geology Professor in Tulane's Department of Earth and Environmental Sciences in the School of Science and Engineering .
Despite these risks, the researchers say state and local governments, regional employers, small businesses and infrastructure providers still have time to begin long-term planning to prepare for for broader shifts in population and economic activity.
"Louisiana is in a unique position to build expertise and infrastructure that will be the foundation for coming generations," said co-author Jesse Keenan , the Favrot II Associate Professor in Tulane's School of Architecture and Built Environment . "Transition planning is not only key to maintaining continuity, but it offers significant economic opportunities, from land-building strategies to renewable energy and new housing development."
The research combines coastal geology with archaeology, demography and public policy to outline a long-term vision for the region. Archaeological evidence shows Indigenous communities historically adapted to environmental change by relocating along the coast.
"Interdisciplinary teams offer the greatest capacity to translate knowledge into action in a manner that addresses one of the greatest societal and economic challenges," Keenan said. "By connecting historical patterns of Indigenous adaptation to present-day migration pathways, we have attempted to take a fresh perspective on where the state will grow next."
Törnqvist pointed to the city of Kiruna in northern Sweden as an example of how managed relocation can work. About 6,000 residents, including the city center, are currently moving due to mining activity beneath the town. The project, expected to finish in 2035, has taken roughly three decades to plan and implement.
"This case of managed relocation also demonstrates how it can spur urban renewal," Törnqvist said. "But it also shows that planning must begin early."
Researchers stress that reducing greenhouse gas emissions remains essential to limit future impacts. The window to keep global warming below the Paris Agreement target of 2 degrees Celsius is expected to close within the next few decades.
"If we fail to do so, the future shoreline will likely retreat even farther inland, eventually putting southern portions of Baton Rouge at risk of flooding," Törnqvist said. "Rapidly reducing carbon emissions will be a major challenge, because we are currently on track for closer to 3 degrees of warming."
Additional co-authors include sociologist Brianna Castro of Yale School of the Environment and archaeologist Jayur Mehta of Florida State University.
