Coupled climate–carbon cycle simulation of the Last Glacial Maximum atmospheric CO2 decrease using a large ensemble of modern plausible parameter sets
During the Last Glacial Maximum (LGM), atmospheric CO 2 was around 90 ppmv lower than during the pre-industrial period. The reasons for this decrease are most often elucidated through factorial experiments testing the impact of individual mechanisms. Due to uncertainty in our understanding of the re...
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ftcopernicus:oai:publications.copernicus.org:cp64934 2023-05-15T13:55:28+02:00 Coupled climate–carbon cycle simulation of the Last Glacial Maximum atmospheric CO2 decrease using a large ensemble of modern plausible parameter sets Kemppinen, Krista M. S. Holden, Philip B. Edwards, Neil R. Ridgwell, Andy Friend, Andrew D. 2019-06-18 application/pdf https://doi.org/10.5194/cp-15-1039-2019 https://cp.copernicus.org/articles/15/1039/2019/ eng eng doi:10.5194/cp-15-1039-2019 https://cp.copernicus.org/articles/15/1039/2019/ eISSN: 1814-9332 Text 2019 ftcopernicus https://doi.org/10.5194/cp-15-1039-2019 2020-07-20T16:22:47Z During the Last Glacial Maximum (LGM), atmospheric CO 2 was around 90 ppmv lower than during the pre-industrial period. The reasons for this decrease are most often elucidated through factorial experiments testing the impact of individual mechanisms. Due to uncertainty in our understanding of the real system, however, the different models used to conduct the experiments inevitably take on different parameter values and different structures. In this paper, the objective is therefore to take an uncertainty-based approach to investigating the LGM CO 2 drop by simulating it with a large ensemble of parameter sets, designed to allow for a wide range of large-scale feedback response strengths. Our aim is not to definitely explain the causes of the CO 2 drop but rather explore the range of possible responses. We find that the LGM CO 2 decrease tends to predominantly be associated with decreasing sea surface temperatures (SSTs), increasing sea ice area, a weakening of the Atlantic Meridional Overturning Circulation (AMOC), a strengthening of the Antarctic Bottom Water (AABW) cell in the Atlantic Ocean, a decreasing ocean biological productivity, an increasing CaCO 3 weathering flux and an increasing deep-sea CaCO 3 burial flux. The majority of our simulations also predict an increase in terrestrial carbon, coupled with a decrease in ocean and increase in lithospheric carbon. We attribute the increase in terrestrial carbon to a slower soil respiration rate, as well as the preservation rather than destruction of carbon by the LGM ice sheets. An initial comparison of these dominant changes with observations and paleoproxies other than carbon isotope and oxygen data (not evaluated directly in this study) suggests broad agreement. However, we advise more detailed comparisons in the future, and also note that, conceptually at least, our results can only be reconciled with carbon isotope and oxygen data if additional processes not included in our model are brought into play. Text Antarc* Antarctic Sea ice Copernicus Publications: E-Journals Antarctic The Antarctic Climate of the Past 15 3 1039 1062 |
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Copernicus Publications: E-Journals |
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ftcopernicus |
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English |
description |
During the Last Glacial Maximum (LGM), atmospheric CO 2 was around 90 ppmv lower than during the pre-industrial period. The reasons for this decrease are most often elucidated through factorial experiments testing the impact of individual mechanisms. Due to uncertainty in our understanding of the real system, however, the different models used to conduct the experiments inevitably take on different parameter values and different structures. In this paper, the objective is therefore to take an uncertainty-based approach to investigating the LGM CO 2 drop by simulating it with a large ensemble of parameter sets, designed to allow for a wide range of large-scale feedback response strengths. Our aim is not to definitely explain the causes of the CO 2 drop but rather explore the range of possible responses. We find that the LGM CO 2 decrease tends to predominantly be associated with decreasing sea surface temperatures (SSTs), increasing sea ice area, a weakening of the Atlantic Meridional Overturning Circulation (AMOC), a strengthening of the Antarctic Bottom Water (AABW) cell in the Atlantic Ocean, a decreasing ocean biological productivity, an increasing CaCO 3 weathering flux and an increasing deep-sea CaCO 3 burial flux. The majority of our simulations also predict an increase in terrestrial carbon, coupled with a decrease in ocean and increase in lithospheric carbon. We attribute the increase in terrestrial carbon to a slower soil respiration rate, as well as the preservation rather than destruction of carbon by the LGM ice sheets. An initial comparison of these dominant changes with observations and paleoproxies other than carbon isotope and oxygen data (not evaluated directly in this study) suggests broad agreement. However, we advise more detailed comparisons in the future, and also note that, conceptually at least, our results can only be reconciled with carbon isotope and oxygen data if additional processes not included in our model are brought into play. |
format |
Text |
author |
Kemppinen, Krista M. S. Holden, Philip B. Edwards, Neil R. Ridgwell, Andy Friend, Andrew D. |
spellingShingle |
Kemppinen, Krista M. S. Holden, Philip B. Edwards, Neil R. Ridgwell, Andy Friend, Andrew D. Coupled climate–carbon cycle simulation of the Last Glacial Maximum atmospheric CO2 decrease using a large ensemble of modern plausible parameter sets |
author_facet |
Kemppinen, Krista M. S. Holden, Philip B. Edwards, Neil R. Ridgwell, Andy Friend, Andrew D. |
author_sort |
Kemppinen, Krista M. S. |
title |
Coupled climate–carbon cycle simulation of the Last Glacial Maximum atmospheric CO2 decrease using a large ensemble of modern plausible parameter sets |
title_short |
Coupled climate–carbon cycle simulation of the Last Glacial Maximum atmospheric CO2 decrease using a large ensemble of modern plausible parameter sets |
title_full |
Coupled climate–carbon cycle simulation of the Last Glacial Maximum atmospheric CO2 decrease using a large ensemble of modern plausible parameter sets |
title_fullStr |
Coupled climate–carbon cycle simulation of the Last Glacial Maximum atmospheric CO2 decrease using a large ensemble of modern plausible parameter sets |
title_full_unstemmed |
Coupled climate–carbon cycle simulation of the Last Glacial Maximum atmospheric CO2 decrease using a large ensemble of modern plausible parameter sets |
title_sort |
coupled climate–carbon cycle simulation of the last glacial maximum atmospheric co2 decrease using a large ensemble of modern plausible parameter sets |
publishDate |
2019 |
url |
https://doi.org/10.5194/cp-15-1039-2019 https://cp.copernicus.org/articles/15/1039/2019/ |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic Sea ice |
genre_facet |
Antarc* Antarctic Sea ice |
op_source |
eISSN: 1814-9332 |
op_relation |
doi:10.5194/cp-15-1039-2019 https://cp.copernicus.org/articles/15/1039/2019/ |
op_doi |
https://doi.org/10.5194/cp-15-1039-2019 |
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Climate of the Past |
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15 |
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3 |
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1039 |
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1062 |
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