New research indicates that rising land beneath Antarctica’s ice sheet could potentially slow down ice loss and mitigate sea-level rise in the coming centuries. However, if greenhouse gas emissions continue to escalate, this phenomenon could inadvertently contribute to a greater increase in sea levels than the melting ice itself.
This insight emerges from an advanced model that closely examines the Earth’s mantle, the layer situated beneath the crust. As the weight of ice diminishes due to melting, the elastic mantle below begins to rebound, lifting the land above it. This rebound effect may slow the ice sheet’s flow where it interacts with the sea, as the reshaping of the seabed limits the ice thickness at its edge. Thinner ice reduces the overall movement of ice into the ocean, a process referred to as “sea level feedback.”
Although researchers have long suspected that this feedback mechanism would play a role in slowing ice loss, uncertainties remained regarding its timeline and variation across different sections of the ice sheet.
Researchers from McGill University conducted a comprehensive study to model the interaction between melting ice and rebounding land. Their simulations accounted for variations in mantle viscosity beneath the continent: East Antarctica, residing above a denser mantle and thicker crust, contrasts with West Antarctica’s rapidly melting glaciers, which lie above a less viscous mantle and thinner crust. This detailed understanding stems from decades of precise measurements of ice sheet elevation changes and seismic data.
In a scenario characterized by very low emissions, the research found that rebounding land could reduce Antarctica’s contribution to global sea level rise by more than half a meter by the year 2500, compared to models that assume a rigid ground beneath the ice. Even under moderate emissions scenarios, noticeable reductions in sea level rise were predicted to occur as early as 2100.
Conversely, under high emissions scenarios, researchers discovered that the rebounding land could add an additional 0.8 meters to sea level by 2500. This increase occurs because the ice sheet’s retreat outpaces the land’s rebound, with the rising seafloor displacing more water into the ocean.
Experts emphasize the significance of this research, noting that the ramifications of our current actions will greatly shape future changes in the 21st and 22nd centuries.
