Antarctica is losing weight, allowing the continent to rise from the ocean like a sponge that was once compressed and can now expand again.

This weight is his ice.

This process is called post-glacial uplift, and new research suggests it will have a major impact on future global sea level rise. It could reduce Antarctica’s contribution by as much as 40 percent, or make things worse, depending on how much heat-trapping, ice-melting fossil fuel we keep emitting.

“With nearly 700 million people living in coastal areas and the potential cost of sea level rise reaching trillions of dollars by the end of the century, understanding the cascading effects of ice melt in Antarctica is critical,” says Natalia Gomez, a glaciologist at McGill University.

And over the past few years, Antarctic ice has remained stubbornly low.

Gomez and his colleagues examined the Earth’s mantle beneath the Antarctic ice sheet and found that some key areas were particularly soft. Seismic data showed that this high level of viscosity was causing the ground to rise unexpectedly quickly.

“Our measurements show that the solid ground that forms the base of the Antarctic Ice Sheet is changing shape surprisingly quickly,” says geologist Terry Wilson of Ohio State University. “The uplift of the land as the surface ice recedes occurs over decades, not millennia.”

The team then used 3D modeling to simulate sea level rise due to Antarctica’s changing land mass under different scenarios. If warming levels remain low, this will contribute to 1.7 meters (5.6 feet) of sea level rise by 2500, but if we allow global warming to continue unabated, this will increase to 19.5 meters (63 feet).

This is because as the ice sheet retreat outpaces the rise, more water is released into the oceans. But if we can slow this melting, the rising land mass will lift some of the ice from the warm ocean waters, making it last longer.

“This research marks a milestone in our ability to better predict the impact of climate change on sea level rise and shape effective environmental policy,” said University of Massachusetts glaciologist Rob DeConto.

Because the Earth is not a perfectly smooth sphere, different parts of our planet are uniquely affected by sea level due to gravity, rotation and geological features.

“Our results support recent findings that low-latitude islands and coastal areas already affected by sea-level rise will experience above-average sea-level rise associated with Antarctic ice loss, regardless of the ice-loss scenario,” Gomez and his team explain.

“This finding highlights climate injustice in low-emission countries, while their impacts and vulnerability to sea level rise are also high.”

The researchers caution that there are still many uncertainties in the model, particularly due to the lack of seismic data from West Antarctica, and that these estimates don’t even take into account what’s happening to the ice in Greenland and mountains around the world.

“To document how quickly our world is changing, it is critical that we continue to improve our ability to make more accurate predictions; it is the only way we can meaningfully look into our future,” Wilson explains.

Sea level rise is already affecting low-lying islands such as Kiribati. Much of South Tarawa, where villagers in Temayka have tried to control the ocean with sandbags, is less than 3 metres above sea level, but earlier this year the sandbags were submerged, flooding homes and contaminating crops and wells with salt.

Meanwhile, wetlands are being squeezed between rising water and human infrastructure like roads. The loss of these ecosystems, which filter water and control erosion, will mean that sea level rise will hit these areas even harder.

“Reducing greenhouse gas emissions will allow solid Earth’s rebound to play a larger role in preserving most of the Antarctic ice sheet and avoiding the worst and most inequitable impacts of future climate change on global coastlines,” Gomez and colleagues conclude.

This study was published on: Science Developments.