Where ice goes when it gets warmer

 

AS if we weren't aware, when the global climate warms, Antarctica gets warmer, and when Antarctica gets warmer, its ice sheets shrink and retreat.

That's what research confirms.

Ancient Sediments Reveal Ice Sheet’s Vulnerability to Warming
Ancient sediments revealed that the Antarctic Ice Sheet retreated inland multiple times during warmer climates.

It's a very interesting study.

"A record of repeated retreat of the West Antarctic Ice Sheet during the past warm climates has been identified by IODP Exp379 Scientists. By analyzing deep-sea sediments from the Amundsen Sea and tracing their geochemical signatures, the study shows that the ice sheet retreated far inland at least five times during the warm Pliocene Epoch. The findings highlight the ice sheet’s sensitivity to warming and its potential to drive future sea-level rise.

The Thwaites and Pine Island glaciers, located in the Amundsen Sea sector of the West Antarctic Ice Sheet (WAIS), are among the fastest-melting glaciers on Earth. Together, they are losing ice more rapidly than any other part of Antarctica, raising serious concerns about the long-term stability of the ice sheet and its contribution to future sea-level rise."

...

"The team analyzed marine sediments collected during the IODP Expedition 379. The sediments recovered from the Site U1532 on the Amundsen Sea continental rise act as a historical archive, recording changes in ice sheets and ocean conditions over millions of years.

They identified two distinct sediment layers reflecting alternating cold and warm climate phases: thick, gray, and finely laminated clays from cold glacial periods, when ice extended across much of the continental shelf; and thinner, greenish layers formed during warmer interglacial periods. The green color comes from the microscopic algae, indicating open, icefree ocean waters. Crucially, these warm-period layers also contain iceberg-rafted debris (IRD), small rock fragments carried by icebergs, that broke off from the Antarctic continent. As these icebergs drifted across the Amundsen Sea and melted, they released this debris onto the seafloor."

...

"The sediment record reveals a consistent four-stage cycle of warming and cooling. During cold glacial periods, the ice sheet was extensive and stable, covering the continent. As the climate warmed, during the early interglacial stage, basal melting began, leading to the inland retreat of the ice sheet. At peak warmth, during the peak interglacial stage, large icebergs calved from the retreating ice margin and transported sediment from the Antarctic interior across the Amundsen Sea. As temperatures cooled again, during the glacial-onset stage, the ice sheet rapidly regrew, pushing previously deposited sediments toward the shelf edge and transporting them further downslope into deeper waters."

Reference: Horikawa K, Iwai M, Hillenbrand CD, et al. Repeated major inland retreat of Thwaites and Pine Island glaciers (West Antarctica) during the Pliocene. Proceedings of the National Academy of Sciences 2026;123(1): doi: 10.1073/pnas.2508341122

Drilling cores show important markers of events during the Pliocene age: At right, the red arrow marks a layer of volcanic ash erupted from a West Antarctic volcano roughly 3 million years ago. At left is a section illustrating thin layers of mud marking the onset of glacial conditions. It overlies a thick bed of pebbly material dropped from icebergs during interglacial conditions. The white box marks the narrow zone containing the unique isotopic signature. Credit: IODP Expedition 379, JOIDES Resolution Science Operator