Rising Antarctic land could mitigate or exacerbate future sea level rise Study finds

Antarctica's melting ice sheet is causing the land beneath to rise, potentially slowing sea level rise over the next few centuries—if greenhouse gas emissions are kept low. However, continued high emissions could lead to an even greater rise in sea levels.

A new model, simulating the mantle beneath Earth’s crust with unprecedented detail, shows that as ice melts and the weight on Antarctica decreases, the elastic mantle rebounds, lifting the land. This uplift can slow ice loss by reshaping the seabed and thinning the ice sheet at its edges, reducing the flow of ice into the sea, Caliber.Az reports via foreign media.

Researchers, led by Natalya Gomez at McGill University, have highlighted the significance of this "sea level feedback" effect, which varies across different parts of the ice sheet due to variations in mantle viscosity and crust thickness. East Antarctica, with its more viscous mantle and thicker crust, contrasts with West Antarctica, where faster-melting glaciers sit atop a less viscous mantle and thinner crust.

Under a low-emissions scenario, rebounding land could reduce Antarctica's contribution to global sea level rise by over half a meter by 2500, compared to models treating the ground as rigid. This effect is less pronounced under moderate emissions but still results in a significant reduction in sea level rise, beginning as early as 2100.

Conversely, in a high-emissions scenario, rebounding land could contribute an additional 0.8 meters to sea level rise by 2500. This occurs because the ice sheet retreats faster than the land rebounds and the rising seafloor displaces more water.

The study, described by Alexander Bradley of the British Antarctic Survey as a significant modeling advance, shows that the impact of rebounding land on sea levels is heavily dependent on future emissions. Alexander Robel of the Georgia Institute of Technology commends the simulation but notes that the scenario where rebounding land increases sea level rise is based on worst-case assumptions about emissions and ice sheet retreat rates.