The glacial ice of the Teton range may have persisted in a dormant state during the early Holocene warming

A continuous record of 10,000 years of fluctuations of alpine glaciers in the Teton Range of Wyoming suggests that some glacial ice in the western United States persisted in a reduced, essentially dormant state during periods of early Holocene warming. The findings challenge the paradigm that all Rocky Mountain glaciers have completely disappeared during these hot, dry conditions, indicating instead that they may have taken the form of smaller debris-covered or rock-encrusted glaciers, which insulated persistent ice from the heat. . This insight could help scientists better understand how the region’s glaciers might respond to future warming. “Long-term survival of glacial ice through warm conditions highlights the potential role of debris-covered glaciers and / or rock glaciers in continuing to provide ecosystem services in the future despite unfavorable climatic conditions,” says Darren Larsen, the author. principal of the study. Retreating glaciers are a hallmark of modern climate change, but due to an incomplete glacial record, little is known about how glaciers in the western United States responded to changes in temperature and rainfall thousands of years ago. To build a continuous record, Larsen and colleagues sampled sediment cores from two lake basins in the Tetons – Delta Lake, a glacial lake basin that provided complementary record of glacier activity, and other nearby lakes including Surprise Lake, a non-glacial lake basin which provided a record of climatic variability. Using radiocarbon dating from accelerator mass spectrometry, the researchers developed sequences of composite rock layers that documented changes in glaciers as they underwent climate change over ten millennia. While sediment flow and meltwater from the Teton Glacier appeared to decrease during a warm period between about 10,000 and 6,300 years ago, the sediments of Lake Delta retained distinctly glacial features that suggest glacial ice remained.

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