What Will Happen When (and if) the West Antarctic Ice Sheet Collapses? UMass Scientists Join International Effort to Find Out

Recent science has shown it is inevitable that the warming Southern Ocean will speed up the melting of parts of the West Antarctic Ice Sheet (WAIS) regardless of our future carbon dioxide emissions. The WAIS holds enough ice to raise the sea level by 5 meters if completely melted.

Image

While the world is already locked in to rising seas, we aren’t yet certain how much and how fast the ice in West Antarctica will melt. Whereas sectors of the WAIS appear highly vulnerable, it remains unclear as to when and under what climatic conditions we will lose the large buttressing ice shelves that stabilize the ice inland. The longer the ice buttresses hold, the slower the melt will be, but if they melt quickly, the world could be looking at a catastrophically rapid rise in sea levels.

To help answer the question of how long the buttressing ice shelves might last, an international initiative, including UMass Amherst professors R. Mark Leckie and Rob DeConto of the Department of Earth, Geographic and Climate Sciences – known as the Sensitivity of the West Antarctic Ice Sheet to 2 Degrees Celsius of Warming (SWAIS2C) project – will turn to the geological record and recover sediment from regions beneath the floating Ross Ice Shelf and near the grounding zone of the West Antarctic Ice Sheet that were deposited during past times when it was warmer than today. These sediments hold environmental information that is key to our future but, until now, has been impossible to obtain.

“We know more about the rocks and composition of the moon than we do about the land beneath the West Antarctic Ice Sheet,” said Richard Levy, co-chief scientist of the SWAIS2C project. There are only 13 locations beneath the ice blanketing West Antarctica where researchers have recovered geological samples. That’s about to change as an international team of researchers and drillers leave Christchurch, New Zealand, for Antarctica on Nov. 16.

Image

SWAIS2C is designed to determine whether the Ross Ice Shelf and West Antarctic Ice Sheet will melt as Earth’s average surface temperature approaches 2°C above those that characterized our planet before the industrial era.

“It is the goal of the Paris Agreement to keep global warming to well below 2°C. Yet we do not know whether the West Antarctic Ice Sheet will lose most of its ice at 1, 2, or 3 degrees of warming, committing us to several meters of sea level rise,” said Tina van de Flierdt, co-chief scientist of the SWAIS2C project.

To understand more about Antarctica’s potential contribution to sea-level rise, a team of drillers, engineers, and researchers will travel ~800 km via traverse and airplane to the southeast margin of the Ross Ice Shelf and drill up to 200 meters below the seafloor to recover a geological record of changing rock types that reflect environmental conditions at the time they formed. The hope is that these records will provide key insights into West Antarctica’s past and Earth’s future.

Leckie, whose specialty is in working with single-celled marine fossils called foraminifera, which have lived on the seafloor for many millions of years, will scrutinize the fossils to get a sense of how sensitive the ice sheet has been to climate change. “Foraminifera are very useful in telling us what past environments were like, including the nature of the seawater near the present day grounding zone” he says. “It’s our hope that the fossil record will tell us whether the ice sheet has been advancing or retreating over the past 10,000 years, which can not only tell us about how alarming the ice-sheet’s current retreat is, but can give us some of the data that modellers use to predict the future effects of melting ice.”

One of those modelers is DeConto. 

“We’ve long needed a sediment core from close to the continent to give us a definitive answer as to whether or not the ice sheet did collapse the last time the world was as warm as it is now,” DeConto says. “We have no direct evidence yet, but once this mission collects its data we can use this information to model future ice sheet scenarios with more precision. This will a go long way toward providing more confident predictions of future sea level rise.”

Antarctic field operations are scheduled to begin in November 2023 on the Kamb Ice Shelf and will continue through 2024. A second field season will begin in November 2024 at the Crary Ice Rise co-led by US science lead Molly Patterson of Binghamton University and Huw Horgan of New Zealand.