In a new study published by AAAS, experts assembled a 10,000-year record of alpine glacier fluctuations in Wyoming’s Teton Range. The analysis of this timeline revealed that some glacial ice in the western United States was able to withstand global warming during the early Holocene.
The researchers found evidence that glacial ice persisted in a dormant state, sealed off underneath debris. The findings contradict the common assumption that all Rocky Mountain glaciers completely disappeared during the warm, dry conditions of the Holocene.
The study suggests that glacial ice shrunk before was covered by dirt, rocks, or other debris, which would have insulated the dwindling ice from the heat and saved it from disappearing.
This remarkable new insight may help scientists better understand how glaciers in the region will respond to future warming.
“The long-term survival of glacial ice through warm conditions highlights the potential role of debris-covered glaciers and/or rock glaciers to continue providing ecosystem services into the future, despite unfavorable climatic conditions,” explained study lead author Darren Larsen.
Due to an incomplete glacial record, little is known about how glacial ice in the western U.S. responded to environmental changes thousands of years ago.
To construct a continuous record, the team sampled sediment cores from two lake basins in the Tetons. Delta Lake provided a record of glacier activity, while other non-glacial lakes including Surprise Lake provided a record of climate variability.
Using accelerator mass spectrometry radiocarbon dating, the researchers developed composite rock layer sequences that revealed changes in the glaciers as they experienced climate shifts over 10,000 years.
Sediment fluctuations and meltwater flow from the Teton Glacier appeared to decrease during a warm period between about 10,000 and 6,300 years ago. At the same time, Delta Lake sediments maintained distinct glacial characteristics which indicate that glacial ice persisted.
The study is published in the journal Science Advances.