The new calculations reveal that following a relative sea level rise of 1 metre, it is estimated that 37% more coastal areas will fall below sea level, affecting up to 132 million individuals.

“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,” said Minderhoud.

Analysis shows average levels are 30cm higher than thought, and up to 150cm in south-east Asia and Indo-Pacific

Sea levels around the world have been underestimated due to inaccurate modelling, with research suggesting ocean levels are far higher than previously understood.

The finding could significantly affect assessments of the future impacts of global heating and the effects on coastal settlements.

Globally, the research found ocean levels are an average of 30cm higher than previously believed, but in some areas of the global south, including south-east Asia and the Indo-Pacific, they may be 100-150cm higher than previously thought.

Rising sea levels are a major threat to coastal communities across the world, and the UN Intergovernmental Panel on Climate Change (IPCC) estimates that by 2100 levels may rise by 28-100cm.