Coastal Sea Levels May Be Higher Than Previously Thought

New study finds measurements may underestimate sea level rise, especially in the Global South

Published on Mar. 4, 2026

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A new study published in Nature found that past research may have underestimated coastal sea level heights around the world by an average of 0.3 meters, or about 1 foot. The study analyzed 385 scientific papers and found that 90% relied on assumed sea levels rather than direct measurements, leading to an underrepresentation of sea level rise, particularly in regions like Southeast Asia and the South Pacific.

Why it matters

This research could have significant implications for policymakers, climate finance, and coastal adaptation plans, as the new estimates suggest up to 37% more land could be below sea level, impacting 77 million to 132 million people globally. Coastal cities like Boston, New Orleans, and San Francisco may face worse flooding than previously thought due to a combination of sea level rise and land subsidence.

The details

The study found that Earth's gravitational models, which are commonly used to assess coastal sea levels, only account for gravity and Earth rotation and do not factor in other local factors like tides, currents, and winds. Less than 9% of existing studies combined land elevation and sea level measurements, but those suffered from conversion errors and data alignment issues. The researchers calculated that sea level was underrepresented by 0.24 to 0.27 meters, with some discrepancies as high as 5.5 to 7.6 meters.

  • The study was published on March 4, 2026.
  • The research analyzed scientific literature published between 2009 and 2025.

The players

Wageningen University & Research

A university in the Netherlands where the researchers who conducted the study are based.

Katharina Seeger

A geographer studying flood hazards and risks at Wageningen University & Research and a co-author of the study.

National Oceanic and Atmospheric Administration (NOAA)

A U.S. government agency that provided data on coastal populations and high tide flooding.

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What they’re saying

“The underrepresentations were particularly noteworthy in regions like Southeast Asia, and the South Pacific.”

— Katharina Seeger, Geographer, Wageningen University & Research (Press conference)

What’s next

The researchers say the new findings indicate a need to re-evaluate the methodology of existing assessments for characterizing sea-level rise impact, which could have implications for policymakers, climate finance, and coastal adaptation plans.

The takeaway

This study suggests that coastal communities around the world, especially in the Global South, may be facing more severe sea level rise and flooding than previously estimated. Policymakers and coastal planners will need to re-examine their models and adaptation strategies to account for these potentially underestimated risks.