Anti‐Phased Miocene Ice Volume and CO2 Changes by Transient Antarctic Ice Sheet Variability
Geological evidence indicates large continental‐scale Antarctic ice volume variations during the early and mid‐Miocene. On million‐year timescales, these variations can largely be explained by equilibrium Antarctic ice sheet (AIS) simulations. In contrast, on shorter orbital timescales, the AIS need...
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Online Access: | https://epic.awi.de/id/eprint/53340/ https://epic.awi.de/id/eprint/53340/1/2020PA003971.pdf https://doi.org/10.1029/2020PA003971 https://hdl.handle.net/10013/epic.f069e76d-8877-4ad3-84a7-32b46620a35d https://hdl.handle.net/ |
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ftawi:oai:epic.awi.de:53340 2023-05-15T13:45:22+02:00 Anti‐Phased Miocene Ice Volume and CO2 Changes by Transient Antarctic Ice Sheet Variability Stap, Lennert B. Knorr, Gregor Lohmann, Gerrit 2020-11-07 application/pdf https://epic.awi.de/id/eprint/53340/ https://epic.awi.de/id/eprint/53340/1/2020PA003971.pdf https://doi.org/10.1029/2020PA003971 https://hdl.handle.net/10013/epic.f069e76d-8877-4ad3-84a7-32b46620a35d https://hdl.handle.net/ unknown AMER GEOPHYSICAL UNION https://epic.awi.de/id/eprint/53340/1/2020PA003971.pdf https://hdl.handle.net/ Stap, L. B. orcid:0000-0002-2108-3533 , Knorr, G. orcid:0000-0002-8317-5046 and Lohmann, G. orcid:0000-0003-2089-733X (2020) Anti‐Phased Miocene Ice Volume and CO2 Changes by Transient Antarctic Ice Sheet Variability , Paleoceanography and Paleoclimatology, 35 (11), e2020PA003971 . doi:10.1029/2020PA003971 <https://doi.org/10.1029/2020PA003971> , hdl:10013/epic.f069e76d-8877-4ad3-84a7-32b46620a35d EPIC3Paleoceanography and Paleoclimatology, AMER GEOPHYSICAL UNION, 35(11), pp. e2020PA003971, ISSN: 2572-4525 Article isiRev 2020 ftawi https://doi.org/10.1029/2020PA003971 2021-12-24T15:46:01Z Geological evidence indicates large continental‐scale Antarctic ice volume variations during the early and mid‐Miocene. On million‐year timescales, these variations can largely be explained by equilibrium Antarctic ice sheet (AIS) simulations. In contrast, on shorter orbital timescales, the AIS needs not be in equilibrium with the forcing and ice volume variations may be substantially different. Here, we introduce a conceptual model, based on ice dynamical model results, to investigate the difference between transient variability and equilibrium differences of the Miocene AIS. In our model, an ice sheet will grow (shrink) by a specific rate when it is smaller (larger) than its equilibrium size. We show that phases of concurrent ice volume increase and rising CO2 levels are possible, even though the equilibrium ice volume decreases monotonically with CO2. When the AIS volume is out of equilibrium with the forcing climate, the ice sheet can still be adapting to a relatively large equilibrium size, although CO2 is rising after a phase of decrease. A delayed response of Antarctic ice volume to (covarying) solar insolation and CO2 concentrations can cause discrepancies between Miocene solar insolation and benthic δ18O variability. Increasing forcing frequency leads to a larger disequilibrium and consequently larger CO2‐ice volume phase differences. Furthermore, an amplified forcing amplitude causes larger amplitude ice volume variability, because the growth and decay rates depend on the forcing. It also leads to a reduced average ice volume, resulting from the growth rates generally being smaller than the decay rates. Article in Journal/Newspaper Antarc* Antarctic Ice Sheet Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) Antarctic Paleoceanography and Paleoclimatology 35 11 |
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Open Polar |
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Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
op_collection_id |
ftawi |
language |
unknown |
description |
Geological evidence indicates large continental‐scale Antarctic ice volume variations during the early and mid‐Miocene. On million‐year timescales, these variations can largely be explained by equilibrium Antarctic ice sheet (AIS) simulations. In contrast, on shorter orbital timescales, the AIS needs not be in equilibrium with the forcing and ice volume variations may be substantially different. Here, we introduce a conceptual model, based on ice dynamical model results, to investigate the difference between transient variability and equilibrium differences of the Miocene AIS. In our model, an ice sheet will grow (shrink) by a specific rate when it is smaller (larger) than its equilibrium size. We show that phases of concurrent ice volume increase and rising CO2 levels are possible, even though the equilibrium ice volume decreases monotonically with CO2. When the AIS volume is out of equilibrium with the forcing climate, the ice sheet can still be adapting to a relatively large equilibrium size, although CO2 is rising after a phase of decrease. A delayed response of Antarctic ice volume to (covarying) solar insolation and CO2 concentrations can cause discrepancies between Miocene solar insolation and benthic δ18O variability. Increasing forcing frequency leads to a larger disequilibrium and consequently larger CO2‐ice volume phase differences. Furthermore, an amplified forcing amplitude causes larger amplitude ice volume variability, because the growth and decay rates depend on the forcing. It also leads to a reduced average ice volume, resulting from the growth rates generally being smaller than the decay rates. |
format |
Article in Journal/Newspaper |
author |
Stap, Lennert B. Knorr, Gregor Lohmann, Gerrit |
spellingShingle |
Stap, Lennert B. Knorr, Gregor Lohmann, Gerrit Anti‐Phased Miocene Ice Volume and CO2 Changes by Transient Antarctic Ice Sheet Variability |
author_facet |
Stap, Lennert B. Knorr, Gregor Lohmann, Gerrit |
author_sort |
Stap, Lennert B. |
title |
Anti‐Phased Miocene Ice Volume and CO2 Changes by Transient Antarctic Ice Sheet Variability |
title_short |
Anti‐Phased Miocene Ice Volume and CO2 Changes by Transient Antarctic Ice Sheet Variability |
title_full |
Anti‐Phased Miocene Ice Volume and CO2 Changes by Transient Antarctic Ice Sheet Variability |
title_fullStr |
Anti‐Phased Miocene Ice Volume and CO2 Changes by Transient Antarctic Ice Sheet Variability |
title_full_unstemmed |
Anti‐Phased Miocene Ice Volume and CO2 Changes by Transient Antarctic Ice Sheet Variability |
title_sort |
anti‐phased miocene ice volume and co2 changes by transient antarctic ice sheet variability |
publisher |
AMER GEOPHYSICAL UNION |
publishDate |
2020 |
url |
https://epic.awi.de/id/eprint/53340/ https://epic.awi.de/id/eprint/53340/1/2020PA003971.pdf https://doi.org/10.1029/2020PA003971 https://hdl.handle.net/10013/epic.f069e76d-8877-4ad3-84a7-32b46620a35d https://hdl.handle.net/ |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Ice Sheet |
genre_facet |
Antarc* Antarctic Ice Sheet |
op_source |
EPIC3Paleoceanography and Paleoclimatology, AMER GEOPHYSICAL UNION, 35(11), pp. e2020PA003971, ISSN: 2572-4525 |
op_relation |
https://epic.awi.de/id/eprint/53340/1/2020PA003971.pdf https://hdl.handle.net/ Stap, L. B. orcid:0000-0002-2108-3533 , Knorr, G. orcid:0000-0002-8317-5046 and Lohmann, G. orcid:0000-0003-2089-733X (2020) Anti‐Phased Miocene Ice Volume and CO2 Changes by Transient Antarctic Ice Sheet Variability , Paleoceanography and Paleoclimatology, 35 (11), e2020PA003971 . doi:10.1029/2020PA003971 <https://doi.org/10.1029/2020PA003971> , hdl:10013/epic.f069e76d-8877-4ad3-84a7-32b46620a35d |
op_doi |
https://doi.org/10.1029/2020PA003971 |
container_title |
Paleoceanography and Paleoclimatology |
container_volume |
35 |
container_issue |
11 |
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1766222295808868352 |