Coastal Sea Levels May Be Higher Than Thought, Study Finds

New research suggests past estimates have underestimated sea level heights, especially in the Global South.

Published on Mar. 4, 2026

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A new study published in Nature found that measurements of coastal sea-level height around the world may be higher than scientists previously thought. The research indicates past studies may have underestimated coastal sea level heights by an average of 0.3 meters, or about 1 foot. The underrepresentation was particularly notable in regions like Southeast Asia and the South Pacific, where sea levels could be up to 3 feet higher than assumed. The findings could mean up to 37% more land is below sea level, impacting 77 million to 132 million people globally.

Why it matters

Accurate assessments of coastal sea level heights are crucial for policymakers, climate finance, and coastal adaptation plans. This new research suggests past estimates may have significantly underestimated the risks and impacts of rising seas, especially for vulnerable regions in the Global South.

The details

The study analyzed 385 peer-reviewed scientific papers on coastal exposure and hazard impact assessments published between 2009 and 2025. Researchers found that 90% of these studies relied on assumed sea levels based on gravitational models rather than direct measurements. These models do not account for factors like tides, currents, and winds that determine local sea levels. Less than 9% of studies combined land elevation and sea level measurements, but those suffered from conversion errors and data alignment issues.

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

The players

Wageningen University & Research

A Dutch university 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.

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What they’re saying

“Coastal sea heights were also underrepresented in Latin America, the west coast of North America, the Caribbean, Africa, the Middle East and the Indo-Pacific.”

— Researchers (ktlo.com)

What’s next

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

The takeaway

This study suggests that past research has significantly underestimated the height of coastal sea levels, particularly in vulnerable regions of the Global South. Accurate assessments of sea level rise are crucial for preparing communities and policymakers for the impacts of climate change.