Washington D.C. – A groundbreaking new study warns that the sea-level rise caused by melting Antarctic ice will not be a uniform “bathtub effect” but will be distributed unevenly across the globe, with regions far from the continent facing the most catastrophic increases. Scientists used combined computer models of the Antarctic ice sheet, solid Earth, and global climate to map these effects, underscoring the severe implications for island nations and coastal communities worldwide.
The research highlights that while the Antarctic ice sheet holds enough frozen water to raise the global average sea level by about 58 meters 190 feet, its melt will create distinct regional “fingerprints” due primarily to the physics of gravity and planetary rotation.
Gravity Drives Uneven Rise
The key to the uneven rise lies in the sheer mass of the ice sheet. Ice sheets are so massive they exert a strong gravitational pull that attracts the surrounding ocean water towards them.
As the ice melts and its mass shrinks, its gravitational pull on the ocean declines. This causes the water previously attracted to the ice to flow away, leading to an unexpected drop in sea level in regions close to the Antarctic coast and a compensating, higher-than-average rise in regions far away. Additionally, the shift in mass changes how the planet rotates, which further redistributes water globally, intensifying the regional variations.
The Global South Faces the Greatest Threat
The study mapped the sea-level contributions under different emissions scenarios, confirming that low-lying coastal areas and island nations located in ocean basins far from Antarctica are exposed to the highest levels of risk:
Moderate Emissions Scenario Under a scenario where emissions are reduced but global warming exceeds 1.5°C, the highest sea-level rise from Antarctic melt alone, up to 1.5 meters 5 feet by 2200 is projected to occur in the Indian, Pacific, and western Atlantic ocean basins. This includes communities in the Caribbean, such as Jamaica, and the central Pacific, such as the Marshall Islands.
High Emissions Scenario emissions continue to rise unchecked, the average sea-level rise from Antarctic melt would be nearly 3 meters 10 feet by 2200. Under this extreme projection, the highest regional rise could reach 4.3 meters 14 feet, hitting a broader swath of the Pacific and Atlantic basins, including regions like Micronesia and Palau.
Climate and Geological Buffers
The research also identified two counterintuitive factors that influence the rate of melting and warming:
• Solid Earth Rebound: As the immense weight of the ice melts, the bedrock underneath Antarctica rebounds, or lifts. This geological movement can raise parts of the ice sheet out of contact with warming ocean water, potentially slowing the rate of melting.
• Ocean Surface Cooling: Icy meltwater flowing into the ocean is shown to reduce ocean surface temperatures in the Southern Hemisphere and tropical Pacific. This action delays greenhouse gas-induced warming by trapping heat in the deep ocean layers.
The findings carry significant implications for climate justice, as the small island nations that have contributed least to global warming are now slated to experience the most devastating consequences of sea-level rise. The research urgently underscores that protecting these vulnerable communities requires reducing global greenhouse gas emissions far faster than nations are currently committing.