Alaska Glaciers Move 5ft/Year

Two massive rock glaciers in Alaska's Wrangell–St. Elias National Park are moving at different speeds, with one moving more than 5 feet (1.5 meters) a year and the other moving at less than half that pace.

The study, which used five years of European Space Agency satellite radar data to map seven active rock glaciers in the park between 2018 and 2022, found that the direction a slope faces and the resulting solar radiation affects the subsurface temperature and the ability of meltwater to reach the layers where movement occurs.

The fastest-moving landform, Sourdough Peak, faces south and sits in the open, while the slower-moving McCarthy Creek rock glacier lies in the partial shadow of the valley wall. The speed-up of Sourdough Peak occurred 72–84 days after spring snowmelt began, and again after late-summer rains.

The researchers, led by SMU's Qingyu Sui, a Ph.D. candidate in Dedman College of Humanities and Sciences, and including Zhong Lu, professor in SMU's Roy M. Huffington Department of Earth Sciences, used satellite radar data to measure very small surface movements across mountain areas that are difficult to reach on foot.

Rock glaciers are slow-moving piles of rocky debris bound together by ice, and scientists treat them as long-term indicators of permafrost health. The study's findings, published in the Journal of Geophysical Research: Earth Surface, provide new insights into the factors that control the movement of these landforms.

## Why it matters The study's findings have significant implications for our understanding of permafrost health and the impact of climate change on these sensitive ecosystems. By understanding the factors that control the movement of rock glaciers, scientists can better predict how these landforms will respond to changing environmental conditions, and what this might mean for the surrounding landscape and ecosystems.