Millennial and orbital-scale variability in a 54 000-year record of total air content from the South Pole ice core
The total air content (TAC) of polar ice cores has long been considered a potential proxy for past ice sheet elevation. Recent work, however, has shown that a variety of other factors also influence this parameter. In this paper we present a high-resolution TAC record from the South Pole ice core (S...
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ftcopernicus:oai:publications.copernicus.org:tc110403 2024-09-15T18:10:01+00:00 Millennial and orbital-scale variability in a 54 000-year record of total air content from the South Pole ice core Epifanio, Jenna A. Brook, Edward J. Buizert, Christo Pettit, Erin C. Edwards, Jon S. Fegyveresi, John M. Sowers, Todd A. Severinghaus, Jeffrey P. Kahle, Emma C. 2023-11-15 application/pdf https://doi.org/10.5194/tc-17-4837-2023 https://tc.copernicus.org/articles/17/4837/2023/ eng eng doi:10.5194/tc-17-4837-2023 https://tc.copernicus.org/articles/17/4837/2023/ eISSN: 1994-0424 Text 2023 ftcopernicus https://doi.org/10.5194/tc-17-4837-2023 2024-08-28T05:24:15Z The total air content (TAC) of polar ice cores has long been considered a potential proxy for past ice sheet elevation. Recent work, however, has shown that a variety of other factors also influence this parameter. In this paper we present a high-resolution TAC record from the South Pole ice core (SPC14) covering the last 54 000 years and discuss the implications of the data for interpreting TAC from ice cores. The SPC14 TAC record shows multiple features of interest, including (1) long-term orbital-scale variability, (2) millennial-scale variability in the Holocene and last glacial period, and (3) a period of stability from 35 to 25 ka. The longer, orbital-scale variations in TAC are highly correlated with integrated summer insolation (ISI), corroborating the potential of TAC to provide an independent dating tool via orbital tuning. Large millennial-scale variability in TAC during the last glacial period is positively correlated with past accumulation rate reconstructions as well as δ 15 N-N 2 , a firn thickness proxy. These TAC variations are too large to be controlled by direct effects of temperature and too rapid to be tied to elevation changes. We propose that grain size metamorphism near the firn surface explains these changes. We note, however, that at sites with different climate histories than the South Pole, TAC variations may be dominated by other processes. Our observations of millennial-scale variations in TAC show a different relationship with accumulation rate than observed at sites in Greenland. Text Greenland ice core Ice Sheet South pole Copernicus Publications: E-Journals The Cryosphere 17 11 4837 4851 |
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Copernicus Publications: E-Journals |
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ftcopernicus |
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English |
description |
The total air content (TAC) of polar ice cores has long been considered a potential proxy for past ice sheet elevation. Recent work, however, has shown that a variety of other factors also influence this parameter. In this paper we present a high-resolution TAC record from the South Pole ice core (SPC14) covering the last 54 000 years and discuss the implications of the data for interpreting TAC from ice cores. The SPC14 TAC record shows multiple features of interest, including (1) long-term orbital-scale variability, (2) millennial-scale variability in the Holocene and last glacial period, and (3) a period of stability from 35 to 25 ka. The longer, orbital-scale variations in TAC are highly correlated with integrated summer insolation (ISI), corroborating the potential of TAC to provide an independent dating tool via orbital tuning. Large millennial-scale variability in TAC during the last glacial period is positively correlated with past accumulation rate reconstructions as well as δ 15 N-N 2 , a firn thickness proxy. These TAC variations are too large to be controlled by direct effects of temperature and too rapid to be tied to elevation changes. We propose that grain size metamorphism near the firn surface explains these changes. We note, however, that at sites with different climate histories than the South Pole, TAC variations may be dominated by other processes. Our observations of millennial-scale variations in TAC show a different relationship with accumulation rate than observed at sites in Greenland. |
format |
Text |
author |
Epifanio, Jenna A. Brook, Edward J. Buizert, Christo Pettit, Erin C. Edwards, Jon S. Fegyveresi, John M. Sowers, Todd A. Severinghaus, Jeffrey P. Kahle, Emma C. |
spellingShingle |
Epifanio, Jenna A. Brook, Edward J. Buizert, Christo Pettit, Erin C. Edwards, Jon S. Fegyveresi, John M. Sowers, Todd A. Severinghaus, Jeffrey P. Kahle, Emma C. Millennial and orbital-scale variability in a 54 000-year record of total air content from the South Pole ice core |
author_facet |
Epifanio, Jenna A. Brook, Edward J. Buizert, Christo Pettit, Erin C. Edwards, Jon S. Fegyveresi, John M. Sowers, Todd A. Severinghaus, Jeffrey P. Kahle, Emma C. |
author_sort |
Epifanio, Jenna A. |
title |
Millennial and orbital-scale variability in a 54 000-year record of total air content from the South Pole ice core |
title_short |
Millennial and orbital-scale variability in a 54 000-year record of total air content from the South Pole ice core |
title_full |
Millennial and orbital-scale variability in a 54 000-year record of total air content from the South Pole ice core |
title_fullStr |
Millennial and orbital-scale variability in a 54 000-year record of total air content from the South Pole ice core |
title_full_unstemmed |
Millennial and orbital-scale variability in a 54 000-year record of total air content from the South Pole ice core |
title_sort |
millennial and orbital-scale variability in a 54 000-year record of total air content from the south pole ice core |
publishDate |
2023 |
url |
https://doi.org/10.5194/tc-17-4837-2023 https://tc.copernicus.org/articles/17/4837/2023/ |
genre |
Greenland ice core Ice Sheet South pole |
genre_facet |
Greenland ice core Ice Sheet South pole |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-17-4837-2023 https://tc.copernicus.org/articles/17/4837/2023/ |
op_doi |
https://doi.org/10.5194/tc-17-4837-2023 |
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The Cryosphere |
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17 |
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11 |
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