MAY 20, 2019 9:09 AM PDT

Nearly One-Fourth of West Antarctica's Ice is Unstable

WRITTEN BY: Tiffany Dazet

Antarctica is suffering from numerous changes due to global climate change, and scientists are unwavering in their work to quantify these changes and their impacts. A research team from the Center for Polar Observation and Modeling (CPOM) recently published the results of one such study in Geophysical Research Letters. Using 25 years of European Space Agency (ESA) satellite altimeter measurements and a model of the regional climate, the team tracked changes in snow and ice cover across Antarctica.

The results of their analysis showed that since 1992, some areas of Antarctica’s ice sheet have thinned by up to 122 m (400 ft.), with the largest impacts seen in West Antarctica. In West Antarctica, ice thinning due to ocean melting has spread across 24% of the region’s glacier ice. This includes two of the regions largest ice streams—the Pine Island and Thwaites Glaciers—which are losing ice five times faster now than at the start of the survey. This ice thinning leads to glacial imbalance—glaciers are losing more mass through melting and iceberg calving than they are gaining through snowfall. 

The research team was led by Professor Andy Shepherd from the University of Leeds School of Earth and Environment. In a press release from Leeds regarding the study, 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.” Shepherd summarized that “altogether, ice losses from east and West Antarctica have contributed 4.6 mm (0.18 in.) to global sea level rise since 1992.”

The team used 800 million measurements of ice sheet height that were recorded by four ESA satellite missions between 1992 and 2017 and models of snowfall produced by climate modeling. This allowed them to determine how much of the thinning was due to changes in climate, and how much was due to changes in weather. They concluded that fluctuations in snowfall do drive small changes in ice sheet height over large areas for a few years at a time. However, the most impactful changes in ice thickness signal glacial imbalance that her persisted for decades.

Shepherd told The Guardian, “along a 3,00 km (1,850 mi.) stretch of West Antarctica, the water in front of this glaciers is too hot.” He continued to describe that this warmer water melts the underside of the glaciers, which reduces friction with the seabed allowing glaciers to slide more quickly into the ocean and become thinner. 

While fluctuations in glacial height are not unheard of, Shepherd stated to The Guardian that this thinning is “rapid in geological terms…the speed of drawing down ice from an ice sheet used to be spoken of in geological timescales, but that has now been replaced by people’s lifetimes.”

Sources: University of Leeds, The Guardian

About the Author
Bachelor's (BA/BS/Other)
Tiffany grew up in Southern California, where she attended San Diego State University. She graduated with a degree in Biology with a marine emphasis, thanks to her love of the ocean and wildlife. With 13 years of science writing under her belt, she now works as a freelance writer in the Pacific Northwest.
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