By Abbas Nazil
New scientific research has revealed that rising sea levels may be significantly underestimated due to previously overlooked Earth physics, suggesting coastal flooding risks could be worse than current climate projections indicate.
The study, published in Geophysical Research Letters, highlights how gravity, crustal deformation and subtle shifts in Earth’s rotation influence the way ocean water is redistributed globally, adding an extra but often ignored factor to sea-level rise projections.
Researchers explained that in addition to well-known drivers such as melting ice caps and ocean thermal expansion, the movement of ocean mass itself creates changes in gravity and land elevation that further amplify local sea-level increases.
According to the findings, when water accumulates in certain regions, it increases gravitational pull in those areas while also causing the Earth’s crust to deform slightly under the added weight, effectively raising sea levels even further along nearby coastlines.
The study also shows that redistribution of ocean mass can subtly alter Earth’s rotation, shifting water toward areas of stronger gravitational attraction and contributing to uneven sea-level changes across different regions.
Scientists noted that these gravitational and deformation effects, known collectively as GRD processes, are not fully incorporated into many current sea-level projection models, including those used in major international climate assessments.
As a result, existing forecasts may be underestimating future coastal sea-level rise by around 15 percent in some scenarios, particularly in regions with broad continental shelves and high-latitude coastlines.
The research suggests that by the year 2100, certain coastal areas could experience up to five centimetres more sea-level rise than previously projected, while some distant ocean regions may see slightly lower levels than expected.
Experts emphasized that although the additional rise may appear small on a global scale, even minor increases can significantly worsen storm surges, flooding events and long-term coastal erosion, especially in vulnerable low-lying communities and island nations.
The study further highlights that tropical and Arctic regions are likely to experience the most pronounced effects due to their geographical characteristics and ocean dynamics, making them more susceptible to amplified flooding risks.
Researchers used advanced climate models under CMIP6 scenarios to simulate ocean mass redistribution and found consistent evidence that GRD effects increase in magnitude as global warming intensifies.
They warned that coastal planners and policymakers must begin incorporating these hidden physical processes into future sea-level rise models to improve the accuracy of risk assessments and adaptation strategies.
The authors stressed that while GRD processes do not introduce a new source of sea-level rise, they significantly reshape how and where the impacts of existing warming-related ocean changes are felt.
They concluded that ignoring these effects leads to systematic underestimation of regional sea-level rise, potentially leaving coastal infrastructure, communities and ecosystems more exposed than previously anticipated.
The findings serve as a reminder that Earth’s complex physical systems, including gravity and crustal movement, play a crucial role in shaping the future of global coastlines under a warming climate.
