Global sea level rise associated with possible collapse of the West Antarctic Ice Sheet is much higher than expected – up to 30% additional volume.
The report presents new calculations of the so-called water displacement mechanism. This occurs when the hard rock of the West Antarctic ice sheet bounces upward as the ice melts and the total weight of the ice sheet decreases. The bedrock is below sea level, so when it rises, it pushes water out of the environment into the ocean, contributing to global sea level rise.
New projections show that if the ice sheet collapses completely, estimates of global sea level rise would increase another meter over 1000 years.
“The magnitude of the effect shocked us. Previous studies that looked at the mechanism have dismissed it as irrelevant. In the event of a collapse of the West Antarctic Ice Sheet, the most cited estimate of the net global mean sea level rise is 3.2 meters. We have shown that this mechanism adds 30% to the total. ”
Linda Peng, GSAS
But this is not just a story of an impact that will be felt hundreds of years from now. One simulation has shown that by the end of this century, global sea level rise caused by the melting of the West Antarctic ice sheet will increase by 30% through water displacement.
Every published forecast of sea level rise due to melting ice cover in West Antarctica based on climate modeling, whether the forecast extends to the end of this century or beyond, will need to be revised upward.
The researchers wanted to study how the ejection mechanism influenced sea level changes when considering the low viscosity or free flowing material of the Earth’s mantle beneath West Antarctica. When they incorporated this low viscosity into their calculations, they realized that water displacement was happening much faster than previous models predicted.
“No matter what scenario we used to collapse the West Antarctic ice sheet, we always found that this additional one meter rise in global sea level always appeared.”
First name Surname Linda Peng, GSASlia
The researchers hope their calculations show that scientists need to consider both the displacement effect and the low viscosity of the mantle beneath Antarctica to accurately estimate the global sea level rise associated with the melting of ice sheets.