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.”
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“Interestingly, we found that the glacier front with the fastest advance also had the fastest retreat, suggesting that hotspots of rapid coastal glacier dynamics occur in the Antarctic Peninsula.”
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‘On Anvers Island, Groff says the group learned that the last time the glacier was at its 2019 position was around 850 years ago as it expanded over the course of several centuries.’
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So expansion and contraction happen anyway, over the centuries and millennia.
“We know, from other studies, that large glaciers of the Antarctic Peninsula are responding quickly to warmer summer air temperatures, and scientists have modeled that the glaciers expanded in the past because of cooler temperatures, and not increased precipitation,” Groff says.
Shows how little they know. Glaciers do not advance due to current increased precipitation. Ice Volume and Weight increase the most in warmest times and cause the ice to advance. When the ice advances, it causes colder which reduces precipitation as the ice advances, as sea ice forms.
These climate people have a static energy chart, static energy theory, static energy models, they expect every change to respond to immediate changes in forcing.
Ice Core Records shows most ice accumulations in warmest times with more ice advancing and causing colder later and less ice accumulations in coldest times and ice retreating and causing warming later. These are dynamic ice cycles that are not included in consensus theory or models.
These dynamic ice cycles are included in ice core records and in actual history. more ice extent caused ice ages to be colder. Less ice extent caused warm times to be warm.
Cooling temperatures accompanied by advancing ice proves the precipitation that mattered, the precipitation that causes the ice advance occurred earlier in the warmer times when the Arctic or the Antarctic Oceans were open and warm to promote the evaporation needed for the more ice accumulation.
This matches with data, ice core records, and history and common sense.
Since when has ‘common sense’ had any influence on ‘climate science’, PCT?
Or data either, come to that.
Reblogged this on Utopia, you are standing in it!.
The key thing here is that glacier retreat has exposed mosses that grew when the glaciers were at least at where they are now, probably further retreated. So if glacier retreat is caused by a warmer climate, its been at least as warm and probably warmer in the recent past.
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
So not just local conditions.
Reblogged this on Climate Collections.