August M
New research suggests global sea levels have been significantly underestimated due to limitations in widely used scientific models.
The findings could reshape projections about how climate change will affect coastal regions around the world.
Scientists say the discrepancy may mean some communities face the impacts of rising seas sooner than expected.
The study, published in the journal Nature and reported by The Guardian, found that average sea levels worldwide may be about 30 centimetres higher than earlier estimates.
In some parts of the global south, particularly in south-east Asia and across the Indo-Pacific, the difference could be even larger, ranging from 100 to 150 centimetres above previous assessments.
Rising sea levels are considered one of the most serious consequences of global heating. The UN’s Intergovernmental Panel on Climate Change (IPCC) has previously projected that sea levels could increase by between 28cm and 100cm by the end of the century.
Modelling problems
Researchers analysed 385 peer-reviewed scientific studies published between 2009 and 2025 to understand how sea levels had been calculated.
The work was led by Dr Philip Minderhoud of Wageningen University in the Netherlands and PhD researcher Katharina Seeger.
According to the study, more than 90% of the analysed research relied on land elevation data linked to global geoid models rather than direct local measurements of sea level.
Geoid models estimate global sea levels using calculations based on the Earth’s gravity and rotation.
Hidden differences
Because these models do not account for several local environmental factors, the calculations may have underestimated sea levels by an average of 24 to 27 centimetres, depending on the model used.
In some locations, the differences between modelled and measured levels were far greater, reaching discrepancies of up to 550 to 760 centimetres.
Minderhoud explained that real-world sea levels are influenced by a range of variables.
“In reality, sea level is influenced by additional factors such as winds, ocean currents, seawater temperature and salinity,” he said.
Coastal risks
Using revised calculations, the researchers estimate that if sea levels rise by one metre, around 37% more coastal land could fall below sea level than previously expected.
This could affect as many as 132 million people living in coastal areas worldwide.
“If sea level is higher for your particular island or coastal city than was previously assumed, the impacts from sea level rise will happen sooner than projected before,” Minderhoud said.
The scientists described the gap between modelling approaches and actual measurements as an “interdisciplinary blind spot”. They noted that many of the studies they reviewed have been referenced in recent IPCC climate reports.
The researchers are calling for coastal hazard assessments to be reassessed using updated elevation data and more precise sea level measurements to better inform climate policy.
Sources: The Guardian, Nature, Wageningen University
