Ending the debate: New research solves longstanding Antarctic climate
change mystery
Discrepancy between terrestrial and marine data resolved; shows that ice sheets vulnerable to small carbon dioxide fluctuations

Date:
February 14, 2022
Source:
University of Massachusetts Amherst
Summary:
New research definitively resolves a long-standing discrepancy in
the geologic record that pitted studies of marine ice-sheet behavior
against those that reconstructed past conditions on land. The
research lends additional weight to evidence that the Antarctic
Ice Sheet is sensitive to small changes in carbon dioxide levels
and that, in the past, large portions of the ice sheet could have
disappeared under carbon dioxide levels similar to today.



FULL STORY ==========================================================================
New research led by the University of Massachusetts Amherst definitively resolves a long-standing discrepancy in the geologic record that pitted
studies of marine ice-sheet behavior against those that reconstructed
past conditions on land. The research, published recently in the journal Geology, and funded by the National Science Foundation and the National Environment Research Council, lends additional weight to evidence that
the Antarctic Ice Sheet is sensitive to small changes in CO2 levels and
that, in the past, large portions of the ice sheet could have disappeared
under CO2 levels similar to today.


========================================================================== There has been a decades-long debate amongst scientists who study
the history of the Antarctic Ice Sheet, and it revolves around the
discrepancy between marine data from the Ross Sea and data collected in
the McMurdo Dry Valleys, an ice-free mountainous coastal region adjacent
to the Ross Sea. In one corner stands marine records from the seafloor
that have shown that the Antarctic Ice Sheet has repeatedly shrunk to
a smaller-than-modern size across the last 10 million years, and that
the ice-covered Ross Sea was periodically open ocean.

This suggests that the Antarctic Ice Sheet is sensitive to relatively
small CO2and temperature fluctuations and receded during past warm
periods.

In the other corner stands terrestrial studies of ancient and
well-preserved landforms in the McMurdo Dry Valleys that reveal
that cold-desert conditions on land were maintained across the same ten-million-year time period, which has led some researchers to conclude
that a stable Antarctic Ice Sheet has persisted across multiple past
warm periods, and therefore may be less susceptible to climate warming
than the marine data suggests.

Is the West Antarctic Ice Sheet sensitive to a warming climate or not? Resolving this debate is of planetary significance, since the same
portions of the Antarctic Ice Sheet that collapsed in the past could
raise future sea levels by 10 feet or more if they were to collapse in
our own time.

Using a series of high-resolution climate and ice-sheet models, Anna
Ruth Halberstadt, who completed this research as part of her Ph.D. in geosciences at UMass Amherst, and her colleagues were able to show
that it is entirely possible for below-freezing temperatures to exist
in the McMurdo Dry Valleys even when the nearby Ross Sea is completely
ice free. "We can now say, 'ok, now we understand why these two sets of
data appeared to be at odds,'" says Halberstadt, the paper's lead author.

Halberstadt and her team conducted a series of experiments using
state-of-the- art climate and sea-ice models to show that the McMurdo
Dry Valleys could certainly have stayed frozen, even during times when
the ice sheet collapsed.

Halberstadt says that "this work finally brings all
of the geologic information neatly into line, and
suggests that large parts of the Antarctic Ice Sheet may
have collapsed under climatic situations similar to today." ========================================================================== Story Source: Materials provided by
University_of_Massachusetts_Amherst. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Anna Ruth W. Halberstadt, Douglas E. Kowalewski, Robert M. DeConto.

Reconciling persistent sub-zero temperatures in the McMurdo
Dry Valleys, Antarctica, with Neogene dynamic marine ice-sheet
fluctuations. Geology, 2022; DOI: 10.1130/G49664.1 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220214183329.htm

--- up 10 weeks, 2 days, 7 hours, 13 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)