In the last 25 years, warming oceans and changing climatic conditions have caused ice throughout West Antarctica to thin, triggering a “dynamical imbalance” across portions of the continent. Though the majority of the ice sheet has remained stable, a study published in Geophysical Research Letters suggests that as much as 24 percent of West Antarctica’s glaciers are impacted.
Scientists poured over 25 years of satellite measurements – an estimated 800 million figures – and compared them against simulations of snowfall between 1992 and 2017. Surface height change was compared to simulated changes in snowfall – the greater the discrepancy, the greater the imbalance.
"This is an important demonstration of how satellite missions can help us to understand how our planet is changing," said study co-author Marcus Engdahl, a scientist at the European Space Agency, in a statement. "The polar regions are hostile environments and are extremely difficult to access from the ground. Because of this, the view from space is an essential tool for tracking the effects of climate change."
In some places, the ice sheet showed thinning by as much as 122 meters (400 feet), leading to nearly one-quarter of glaciers in this region to become unstable as they lose more mass through melting and calving than they’ve gained through snowfall accumulation.
"In parts of Antarctica, the ice sheet has thinned by extraordinary amounts, and so we set out to show how much was due to changes in climate and how much was due to weather," said polar scientist Andy Shepherd, from the University of Leeds, in a statement.
Warmer temperatures and changes in precipitation levels, among other climatic changes, can trigger a long-term loss in ice sheet mass, further driving global sea level rise. The scientists note that ice loss from both East and West Antarctica has contributed to a total sea level rise of around 4.6 millimeters during the same time period.
"Knowing how much snow has fallen has really helped us to detect the underlying change in glacier ice within the satellite record," Shepherd said. "We can see clearly now that a wave of thinning has spread rapidly across some of Antarctica's most vulnerable glaciers, and their losses are driving up sea levels around the planet.
Two regions – in particular, Pine Island and Thwaites glacier basins – have seen as much as five time greater rates of ice loss than at the beginning of the survey. The data confirms that these two areas are “by far the largest regional contributors to global sea level rise.”