New study: Sea level rise may submerge wider areas than expected

Dubai, United Arab Emirates - New research has revealed that sea levels along the world's coasts are much higher than previously thought, with the increase in some areas exceeding almost a metre, raising concerns that the world is underestimating the threat to come and how quickly coastlines are disappearing. Sea level rise is one of the most visible and alarming impacts of the human-induced climate crisis, threatening hundreds of millions of people living along coastlines around the world.

Scientists believe that a global sea level rise of about six inches (about 15 centimetres) by 2050 is inevitable. But it is possible that the calculations on which these estimates are based do not start from an accurate foundation, according to the study published Wednesday in the scientific journal Nature.

To predict how sea level rise will affect coastal communities, scientists often rely on a model that calculates sea level based on the Earth's gravity field and Earth's rotation. But this model does not take other influencing factors into account, such as tides, winds, sea currents, water temperature, and salinity.

One of the study's authors and associate professor at Wageningen Research University in the Netherlands, Philippe Minderhoud, explained that obtaining reliable information about sea level requires combining this model with realistic data from satellites capable of accurately measuring sea surface height. The report's authors analyzed 385 peer-reviewed scientific studies published over the past 15 years on sea level rise and the risks it poses to coastlines.

It turns out that 90% of these studies relied only on model assumptions, rather than on measured observations. Minderhoud described this as a “systematic blind spot” that has widely underestimated coastal sea levels and the vulnerability of populations to associated risks.

The report found that global coastal sea levels are on average about 0.3 meters higher than currently assumed, while in some regions, such as Southeast Asia and parts of the Pacific, the increase is almost a meter or higher. The results suggest that if sea levels rose by about a metre, it would submerge 37% more land area than currently estimated, potentially affecting 132 million people around the world.

“In simple terms, if sea level is actually higher than previously thought for an island or coastal city, then the effects of sea level rise will appear earlier than forecasts indicate,” Minderhood said. For his part, Associate Professor at the University of Bristol, Matt Palmer, who was not involved in the study, said that the results show that “the effects of sea level rise under climate change have been systematically underestimated.”

Bristol Glaciology Center director Jonathan Bamber, who has studied sea level rise for nearly twenty years, said the results really surprised him. Bamber added that inaccurate assumptions about sea level today will have major repercussions in the future “in terms of the area that might be affected and the number of people that might be affected.”

But it does not change expectations about how much sea level rise may occur in the future. The study's authors stressed that more research is needed to reassess global sea levels and understand the full ramifications of the risks facing coastal communities now and in the future.