Enigmatic Meltwater Oasis: Exploring the Amery Ice Shelf’s Hidden Ponds

As 2024 came to a close, less than midway through the melting season in Antarctica, the icy continent had already experienced periods of extensive melting along its coastal regions. By the beginning of 2025, meltwater was still observable atop the ice sheet’s surface, stretching from the Antarctic Peninsula in the west to ice shelves in the east, encompassing East Antarctica’s Amery Ice Shelf.

The OLI (Operational Land Imager) on Landsat 8 captured these images on January 1, 2025. Several glaciers—the Lambert, Mellor, and Fisher—merge near the underlying continent’s boundary. This ice flows out from the coast and onto the ocean’s surface, forming the Amery Ice Shelf and filling Prydz Bay. The shelf’s southern (interior) side, close to its grounding line, is depicted in the middle-right of the image above. (The complete shelf is illustrated in this image obtained by NASA’s Terra satellite.)

“The Amery is distinct among Antarctic ice shelves due to its extensive interior length—surpassing 500 kilometers (300 miles)—along with substantial adjacent bedrock exposures,” stated Christopher Shuman, a glaciologist at the University of Maryland, Baltimore County. “Nonetheless, even in the frigid depths of East Antarctica, seasonal changes induce surface melting deep inland from the coastal ice margin.”

Ice shelves like the Amery are crucial in restraining, or buttressing, the flow of ice from inland and upstream areas. This buttressing can decelerate the discharge of glacial ice into the ocean, thereby mitigating contributions to sea level rise compared to unbuttressed ice regions. Thick, stable ice shelves fulfill this buttressing function most effectively. However, when meltwater seeps through cracks within the ice, it can compromise the integrity of the ice shelf.

Evident in the intricate image above is the melting occurring on the ice shelf. The blue areas are melt ponds—sections where the snow has melted and accumulated in low-lying places on the shelf. Melt ponds typically develop on the Amery during the Antarctic melt season, which takes place annually from November 1 through March 31 with increasing temperatures of the austral summer. Winds can also contribute, clearing away winter snow and revealing bare, blue ice that is more susceptible to melting due to its darker color absorbing greater amounts of heat.

Bert Wouters, a researcher at TU Delft, mentioned that he has observed more extensive melt pond formation on the Amery in previous seasons. “Conversely, it’s still relatively early, so it’s probable that we’ll observe additional ponding in the upcoming weeks,” he remarked.

The ponding displayed here followed a widespread melting event around the edges of the Antarctic Ice Sheet in mid-December 2024, succeeded by further melting toward the month’s conclusion which led to an historic record melt extent on December 25 and 26, as reported by the National Snow and Ice Data Center. At that stage, satellite-based passive microwave sensors noted melting across over 3 percent of the ice sheet’s surface.

Ponding on the Amery is generally restricted to regions near the shelf’s grounding line, according to Wouters. He pointed out that closer to the ice shelf’s edge (beyond this view, to the right), ponding is inhibited by colder and drier conditions that permit meltwater to refreeze within the snowpack. However, research has indicated, Wouters noted, “that it requires only a few additional degrees of warming to render these areas susceptible to ponding.”

NASA Earth Observatory images by Wanmei Liang, utilizing Landsat data from the U.S. Geological Survey. Story by Kathryn Hansen.