New Tulane Studies Show Rising Seas and Sinking Land Are Reshaping Coastal Risk
Research led by Tulane scientist Sönke Dangendorf is helping redefine how scientists understand sea-level rise, coastal flooding, and the accelerating risks facing communities worldwide
For Sönke Dangendorf, the story of sea-level rise has never been just about the ocean.
As a coastal scientist at Tulane University, Dangendorf studies the interconnected systems that shape flood risk along coastlines around the world. Ocean warming, melting ice sheets, shifting ocean circulation, subsiding land, climate variability, and extreme flooding are often studied separately. Dangendorf’s work brings those pieces together to better understand how coastal risk is changing and why many communities are already experiencing impacts faster than expected.
“Coastal resilience needs to move away from static, one-size-fits-all approaches toward strategies that are adaptive and locally informed.”
Sönke Dangendorf
That work is now gaining international attention through a series of major publications released in recent weeks across some of the world’s leading scientific journals, including Nature Climate Change, Nature Geoscience, and Science Advances.
Together, the studies paint a striking picture of a coastal system already being reshaped by climate change and land motion, one where rising seas and sinking coastlines are combining to accelerate flood risk worldwide.
“A common misconception is that sea-level rise is uniform, like water rising evenly in a bathtub,” Dangendorf said. “In reality, sea level varies strongly by region and time, influenced not only by global warming but also by ocean circulation, winds, gravitational effects of melting ice sheets, and vertical land motion. As a result, some coastlines experience much faster rise than the global mean, while others see slower change or temporary declines. Sea-level change is also not purely gradual. Climate variability can strongly modulate impacts on shorter timescales. Overall, understanding sea-level change requires integrating physics, observations, and statistical modeling rather than relying on a single global number.”
One of the newly published studies, appearing in Science Advances, helps resolve a long-standing challenge in climate science: fully accounting for the causes of global sea-level rise since 1960.
Using decades of observational records, the research confirms that human-driven ocean warming and ice loss have dramatically accelerated sea-level rise over the modern era, pushing the rate to nearly twice its historical pace.
The findings strengthen scientific understanding of how greenhouse gas emissions are reshaping the physical climate system and provide one of the clearest accounting efforts yet for the drivers behind modern sea-level rise.
But the research also highlights a critical reality often lost in global averages. Even when scientists know how much oceans are rising overall, local impacts can vary dramatically from place to place.
That question became the focus of Dangendorf’s second study, published in Nature Geoscience, which examined how vertical land motion has altered sea-level measurements around the world over the past century.
Vertical land motion refers to the slow sinking or rising of land caused by both natural and human-driven processes. Groundwater extraction, oil and gas production, sediment compaction, tectonic activity, earthquakes, and glacial rebound can all alter land elevation over time, significantly changing how sea-level rise is experienced locally.
By comparing long-term sea-level reconstructions with tide gauge observations from around the world, the research team was able to isolate how land itself has moved at hundreds of coastal locations since 1900.
What emerged was a far more dynamic picture than many existing models assumed.
“We found that land motion is often not steady, it can accelerate, slow down, or even reverse over time,” Dangendorf said. “With our large, global dataset, this variability becomes better visible and helps explain apparent sea-level changes that are driven by the land moving beneath the measurements. This doesn’t change the global sea-level picture, but it matters a lot locally. Ignoring land motion can bias estimates of how fast sea level is rising at specific sites. Accounting for it makes local projections more accurate and more useful for coastal planning.”
In some regions, the researchers identified accelerating subsidence linked to groundwater withdrawals, oil and gas extraction, and urban development. In others, earthquakes and tectonic activity caused sudden shifts followed by years of gradual adjustment. Even locations that appeared stable over short time periods revealed substantial long-term variability when viewed across decades of data.
The implications extend beyond scientific measurement. If land motion changes over time, projections based on historical linear trends may significantly underestimate or overestimate future coastal risk.
Dangendorf’s third study, published in Nature Climate Change, moves from measurement to real-world consequences.
The study examines how rising seas have already changed the likelihood of extreme coastal flooding events around the world.
Using tide gauge records, climate model simulations, and attribution techniques, the researchers analyzed how often extreme sea-level events have occurred over the past century and how those probabilities have shifted over time with sea-level rise.
The results show that events historically expected to occur once every hundred years are now happening far more frequently in many coastal regions, with human-driven climate change playing a major role in that acceleration.
Importantly, the study found that the increase is not necessarily because storms themselves are intensifying. Instead, higher baseline sea levels make it easier for tides, storm surges, and routine coastal flooding events to cross damaging thresholds.
“In practice, many communities are already experiencing this but don’t always link it directly to sea-level rise,” Dangendorf said. “They may notice more frequent flooding, higher insurance costs, or recurring disruptions. The underlying driver is a gradual rise in baseline water levels that amplifies both everyday flooding and storm impacts. This leads to more nuisance flooding, road closures, saltwater intrusion, and greater damage even from storms that aren’t stronger. While communities can recover from rare extreme events, coping with them repeatedly is far more challenging.”
Together, the three studies reveal how global climate change and local land dynamics are interacting to reshape coastal risk in ways that cannot be captured through simple global averages alone.
That interaction is especially relevant in Louisiana and along the Gulf Coast, where subsidence, sediment loss, and decades of resource extraction have contributed to ongoing land loss and increasing flood exposure across the Mississippi River Delta.
“The New Orleans area has one of the most advanced flood protection systems in the country,” Dangendorf said. “However, as sea level rises and the land subsides, the effective level of protection declines, requiring continuous upgrades to keep pace with risk. Current planning still tends to underestimate how quickly flood frequencies can increase as baseline water levels shift, especially when subsidence and nonlinear land motion are not fully considered. Without accounting for these dynamics, even well-designed systems risk falling behind the conditions they are meant to protect against.”
Beyond their scientific findings, the studies also contribute to a growing body of research directly connecting climate change to measurable impacts already affecting communities today.
By quantifying how human-driven warming has accelerated sea-level rise and increased the frequency of coastal flooding events, the research provides observation-based evidence that climate change is already reshaping hazards worldwide. The work also reinforces the need for coastal adaptation strategies that are flexible, locally informed, and continuously updated as conditions evolve.
“Coastal resilience needs to move away from static, one-size-fits-all approaches toward strategies that are adaptive and locally informed,” Dangendorf said. “Our findings show that risk is already changing, so planning must account for shifting baselines, land motion, and increasing extremes, not just historical conditions. That means continuous reassessment of protection levels, flexible design standards, and closer integration of observations into decision-making. Going forward, adaptation isn’t a one-time investment, it’s an ongoing process that has to evolve as the risks do.”
For communities like New Orleans, he said, the research offers both a validation of past investments and a warning about the future.
Sea-level rise and land motion are not distant concerns unfolding sometime decades from now. They are already altering the baseline conditions coastal communities depend on to plan, build, and protect infrastructure.
“If there is one takeaway, it’s that our environment is not static, it is already changing in measurable ways, and those changes affect the risks communities face,” Dangendorf said. “Rather than viewing this through an ideological lens, it’s more productive to focus on the observable evidence and what it means for preparedness and planning. Sea-level rise and land motion are shifting the baseline, so past experience is no longer a reliable guide for future risk. Being prepared means acknowledging these changes and adapting proactively to what we can already see happening.”
Study links:
Variable contributions of vertical land motion to sea-level change inferred at tide gauges
Nature Geoscience
https://www.nature.com/articles/s41561-026-02005-1
Improved closure of the global mean sea-level budget from observational advances since 1960
Science Advances
https://www.science.org/doi/10.1126/sciadv.aea0652
Human-driven sea-level rise has quadrupled the frequency of coastal sea-level extremes since 1900
Nature Climate Change
https://www.nature.com/articles/s41558-026-02659-0
