Credit: coolantarctica.com
Glaciers advance and retreat. Repeating cycles of natural climate variation exposed.
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Receding glaciers in the northern Antarctic Peninsula are uncovering and reexposing black moss that provides radiocarbon kill dates for the vegetation, a key clue to understanding the timing of past glacier advances in that region, says Phys.org.
A University of Wyoming researcher led a study that determined the black moss kill dates coincide with evidence of glacier advances from other studies that found such events occurred 1,300, 800 and 200 calibrated years prior to 1950.
“We used radiocarbon ages, or kill dates, of previously ice-entombed dead black mosses to reveal that glaciers advanced during three distinct phases in the northern Antarctic Peninsula over the past 1,500 years,” says Dulcinea Groff, a postdoctoral research associate in the UW Department of Geology and Geophysics.
Groff was lead author of a paper titled “Kill dates from re-exposed black mosses constrain past glacier advances in the northern Antarctic Peninsula” that appeared Jan. 20 in Geology, a journal that publishes timely, innovative and provocative articles relevant to its international audience, representing research from all fields of the geosciences.
Researchers from Lehigh University, the University of Hawaii-Manoa, and Northeast Normal University and the Chinese Academy of Sciences, both in Changchun, in the Jiln Province of China, contributed to the paper.
Mosses are one of the few types of plants living in Antarctica and can become overridden and killed by advancing glaciers. The timing of when the glaciers killed the moss provides an archive of glacier history, Groff says.
For example, when glaciers expand or advance, they can entomb or cover the plant. This starves the plant of light and warmth. The date the plant died is the same time the glacier advanced over that location.
“As glaciers recede, these previously entombed mosses are exposed and are dead and black,” Groff explains. “What’s so valuable about these kill dates compared to other records—like the ages of glacial erratics or penguin remains—is their accuracy. They provide a clearer picture of the climate history owing to their direct carbon exchange with the atmosphere and decreased error around the age estimate.”
Full article here.
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February 3, 2023 at 04:09AM
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