UNIVERSITY PARK, Pa. — Findings from an international team of researchers, including those from Penn State, suggest that Earth's natural forces could substantially reduce the melting of the West Antarctic Ice Sheet and its impact on rising sea levels, but only if carbon emissions are swiftly reduced in the coming decades. By the same token, if emissions continue on the current rising trajectory, Antarctic ice loss could lead to more sea level rise in the future than previously thought, according to the researchers.
The researchers published their findings in Science Advances.
“The West Antarctic Ice Sheet (WAIS) is one of the largest ice masses on Earth and how it responds to future warming from greenhouse gas emissions is one of the greatest uncertainties in estimating future ice sheet stability and projecting ice mass losses” said Andrew Nyblade, professor of geosciences at Penn State and co-author on the study. “This is especially important since nearly 700 million people live in coastal areas and could be affected by sea level rise, and its impact could possibly reach trillions of dollars by the end of the century.”
The study, led by McGill University in Canada and included a team of scientists from Canada and the United States, focuses on how parts of the WAIS interact with the solid Earth beneath and how that dynamic is influenced by carbon emission levels. This relationship has not been thoroughly explored in previous studies, the researchers said.
“Our findings show that while some sea level rise is inevitable, swift and substantive action to lower emissions could prevent some of the most destructive impacts of climate change, particularly for coastal communities,” said lead author Natalya Gomez, associate professor and Canada Research Chair in Ice sheet-Sea level interactions at McGill University.
Nyblade explained that the ice sheet changes are influenced by and can impact more than sea levels.
“The solid Earth can have a big impact on what could happen to the ice sheet," Nyblade said. “The weight of glaciers and ice sheets depresses the land beneath them, and as the ice melts, the Earth’s surface rebounds with the reduced load.”
The zone where the ice sheet transitions from sitting on bedrock to floating on the ocean is referred to as the grounding line, Nyblade said.
“Much of the WAIS is grounded below sea level, making it susceptible to melting by warming ocean waters flowing beneath the ice sheet,” Nyblade said. "As the Earth pushes back up from underneath, the bottom of the ice rises so it’s harder for seawater to get underneath, slowing the melting process.”
The researchers found that if emissions drop quickly, limiting global warming, this uplift can act as a natural brake on ice-mass loss and this dynamic can reduce Antarctica’s contribution to sea-level rise by up to 40%.
However, their model showed that if carbon outputs keep pace and the planet heats up quickly, the rebounding land will not be enough to slow the rapidly melting ice, and instead pushes more ocean water away from Antarctica, accelerating sea-level rise along populated coastlines.