Articles | Volume 4, issue 4
https://doi.org/10.5194/cp-4-311-2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Special issue:
https://doi.org/10.5194/cp-4-311-2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
The carbon cycle during the Mid Pleistocene Transition: the Southern Ocean Decoupling Hypothesis
P. Köhler
Alfred Wegener Institute for Polar and Marine Research, PO Box 120161, 27515 Bremerhaven, Germany
R. Bintanja
KNMI (Royal Netherlands Meteorological Institute), Wilhelminalaan 10, 3732 GK De Bilt, Netherlands
Related authors
Peter Köhler
Clim. Past Discuss., https://doi.org/10.5194/cp-2024-63, https://doi.org/10.5194/cp-2024-63, 2024
Preprint under review for CP
Short summary
Short summary
Using a carbon cycle model I here show that the 405-kyr periodicity found in marine δ13C during the last 5 million years and the offset in atmospheric δ13CO2 between the last and the penultimate glacial maximum are probably related to each other. They can be explained by variations in the δ13C signature of weathered carbonate rock or of volcanically degassed CO2 which vary mainly with obliquity (41-kyr) suggesting that northern hemispheric land ice sheets are their ultimate drivers.
Peter U. Clark, Jeremy D. Shakun, Yair Rosenthal, Chenyu Zhu, Jonathan M. Gregory, Peter Köhler, Zhengyu Liu, Daniel P. Schrag, and Patrick J. Bartlein
EGUsphere, https://doi.org/10.5194/egusphere-2024-3010, https://doi.org/10.5194/egusphere-2024-3010, 2024
This preprint is open for discussion and under review for Climate of the Past (CP).
Short summary
Short summary
We reconstruct changes in mean ocean temperature (ΔMOT) over the last 4.5 Myr. We find that the ratio of ΔMOT to changes in global mean sea surface temperature was around 0.5 before the Middle Pleistocene Transition but was 1 thereafter. We subtract our ΔMOT reconstruction from the global δ18O record to derive the δ18O of seawater. Finally, we develop a theoretical understanding of why the ratio of ΔMOT/ΔGMSST changed over the Plio-Pleistocene.
Peter Köhler and Stefan Mulitza
Clim. Past, 20, 991–1015, https://doi.org/10.5194/cp-20-991-2024, https://doi.org/10.5194/cp-20-991-2024, 2024
Short summary
Short summary
We constructed 160 kyr long mono-specific stacks of δ13C and of δ18O from the wider tropics from the planktic foraminifera G. ruber and/or T. sacculifer and compared them with carbon cycle simulations using the BICYCLE-SE model. In our stacks and our model-based interpretation, we cannot detect a species-specific isotopic fractionation during hard-shell formation as a function of carbonate chemistry in the surrounding seawater, something which is called a carbonate ion effect.
Martin Butzin, Ying Ye, Christoph Völker, Özgür Gürses, Judith Hauck, and Peter Köhler
Geosci. Model Dev., 17, 1709–1727, https://doi.org/10.5194/gmd-17-1709-2024, https://doi.org/10.5194/gmd-17-1709-2024, 2024
Short summary
Short summary
In this paper we describe the implementation of the carbon isotopes 13C and 14C into the marine biogeochemistry model FESOM2.1-REcoM3 and present results of long-term test simulations. Our model results are largely consistent with marine carbon isotope reconstructions for the pre-anthropogenic period, but also exhibit some discrepancies.
Luke Skinner, Francois Primeau, Aurich Jeltsch-Thömmes, Fortunat Joos, Peter Köhler, and Edouard Bard
Clim. Past, 19, 2177–2202, https://doi.org/10.5194/cp-19-2177-2023, https://doi.org/10.5194/cp-19-2177-2023, 2023
Short summary
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Radiocarbon is best known as a dating tool, but it also allows us to track CO2 exchange between the ocean and atmosphere. Using decades of data and novel mapping methods, we have charted the ocean’s average radiocarbon ″age” since the last Ice Age. Combined with climate model simulations, these data quantify the ocean’s role in atmospheric CO2 rise since the last Ice Age while also revealing that Earth likely received far more cosmic radiation during the last Ice Age than hitherto believed.
Claudia Hinrichs, Peter Köhler, Christoph Völker, and Judith Hauck
Biogeosciences, 20, 3717–3735, https://doi.org/10.5194/bg-20-3717-2023, https://doi.org/10.5194/bg-20-3717-2023, 2023
Short summary
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This study evaluated the alkalinity distribution in 14 climate models and found that most models underestimate alkalinity at the surface and overestimate it in the deeper ocean. It highlights the need for better understanding and quantification of processes driving alkalinity distribution and calcium carbonate dissolution and the importance of accounting for biases in model results when evaluating potential ocean alkalinity enhancement experiments.
Ying Ye, Guy Munhoven, Peter Köhler, Martin Butzin, Judith Hauck, Özgür Gürses, and Christoph Völker
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2023-181, https://doi.org/10.5194/gmd-2023-181, 2023
Revised manuscript accepted for GMD
Short summary
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Many biogeochemistry models assume all material reaching the seafloor is remineralized and returned to solution, which is sufficient for studies on short-term climate change. Under long-term climate change the storage of carbon in sediments slows down carbon cycling and influences feedbacks in the atmosphere-ocean-sediment system. Here we coupled a sediment model to an ocean biogeochemistry model and found a shift of carbon storage from the atmosphere to the ocean-sediment system.
Lennert B. Stap, Peter Köhler, and Gerrit Lohmann
Earth Syst. Dynam., 10, 333–345, https://doi.org/10.5194/esd-10-333-2019, https://doi.org/10.5194/esd-10-333-2019, 2019
Short summary
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Processes causing the same global-average radiative forcing might lead to different global temperature changes. We expand the theoretical framework by which we calculate paleoclimate sensitivity with an efficacy factor. Applying the revised approach to radiative forcing caused by CO2 and land ice albedo perturbations, inferred from data of the past 800 000 years, gives a new paleo-based estimate of climate sensitivity.
Peter Köhler, Christoph Nehrbass-Ahles, Jochen Schmitt, Thomas F. Stocker, and Hubertus Fischer
Earth Syst. Sci. Data, 9, 363–387, https://doi.org/10.5194/essd-9-363-2017, https://doi.org/10.5194/essd-9-363-2017, 2017
Short summary
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We document our best available data compilation of published ice core records of the greenhouse gases CO2, CH4, and N2O and recent measurements on firn air and atmospheric samples covering the time window from 156 000 years BP to the beginning of the year 2016 CE. A smoothing spline method is applied to translate the discrete and irregularly spaced data points into continuous time series. The radiative forcing for each greenhouse gas is computed using well-established, simple formulations.
Peter Köhler, Lennert B. Stap, Anna S. von der Heydt, Bas de Boer, and Roderik S. W. van de Wal
Clim. Past Discuss., https://doi.org/10.5194/cp-2016-23, https://doi.org/10.5194/cp-2016-23, 2016
Revised manuscript not accepted
Short summary
Short summary
Evidence indicate that specific equilibrium climate sensitivity, the global annual mean surface temperature change as a response to a change in radiative forcing, is state dependent. We here show that the interpretation of data in the state-dependent case is not straightforward. We analyse the differences of a point-wise approach and one based on a piece-wise linear analysis, combine both, compare with potential model results and apply the theoretical concepts to data of the last 800 kyr.
P. Köhler, B. de Boer, A. S. von der Heydt, L. B. Stap, and R. S. W. van de Wal
Clim. Past, 11, 1801–1823, https://doi.org/10.5194/cp-11-1801-2015, https://doi.org/10.5194/cp-11-1801-2015, 2015
Short summary
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We find that the specific equilibrium climate sensitivity due to radiative forcing of CO2 and land ice albedo has been state-dependent for the last 2.1Myr (most of the Pleistocene). Its value is ~45% larger during intermediate glaciated climates and interglacial periods than during Pleistocene full glacial conditions. The state dependency is mainly caused by a latitudinal dependency in ice sheet area changes. Due to uncertainties in CO2, firm conclusions for the Pliocene are not yet possible.
R. Schneider, J. Schmitt, P. Köhler, F. Joos, and H. Fischer
Clim. Past, 9, 2507–2523, https://doi.org/10.5194/cp-9-2507-2013, https://doi.org/10.5194/cp-9-2507-2013, 2013
R. S. W. van de Wal, B. de Boer, L. J. Lourens, P. Köhler, and R. Bintanja
Clim. Past, 7, 1459–1469, https://doi.org/10.5194/cp-7-1459-2011, https://doi.org/10.5194/cp-7-1459-2011, 2011
P. Köhler, G. Knorr, D. Buiron, A. Lourantou, and J. Chappellaz
Clim. Past, 7, 473–486, https://doi.org/10.5194/cp-7-473-2011, https://doi.org/10.5194/cp-7-473-2011, 2011
P. Köhler and A. Huth
Biogeosciences, 7, 2531–2543, https://doi.org/10.5194/bg-7-2531-2010, https://doi.org/10.5194/bg-7-2531-2010, 2010
P. Köhler
Clim. Past Discuss., https://doi.org/10.5194/cpd-6-1453-2010, https://doi.org/10.5194/cpd-6-1453-2010, 2010
Revised manuscript has not been submitted
P. Köhler, H. Fischer, J. Schmitt, and G. Munhoven
Biogeosciences, 3, 539–556, https://doi.org/10.5194/bg-3-539-2006, https://doi.org/10.5194/bg-3-539-2006, 2006
P. Köhler and H. Fischer
Clim. Past, 2, 57–78, https://doi.org/10.5194/cp-2-57-2006, https://doi.org/10.5194/cp-2-57-2006, 2006
Peter Köhler
Clim. Past Discuss., https://doi.org/10.5194/cp-2024-63, https://doi.org/10.5194/cp-2024-63, 2024
Preprint under review for CP
Short summary
Short summary
Using a carbon cycle model I here show that the 405-kyr periodicity found in marine δ13C during the last 5 million years and the offset in atmospheric δ13CO2 between the last and the penultimate glacial maximum are probably related to each other. They can be explained by variations in the δ13C signature of weathered carbonate rock or of volcanically degassed CO2 which vary mainly with obliquity (41-kyr) suggesting that northern hemispheric land ice sheets are their ultimate drivers.
Peter U. Clark, Jeremy D. Shakun, Yair Rosenthal, Chenyu Zhu, Jonathan M. Gregory, Peter Köhler, Zhengyu Liu, Daniel P. Schrag, and Patrick J. Bartlein
EGUsphere, https://doi.org/10.5194/egusphere-2024-3010, https://doi.org/10.5194/egusphere-2024-3010, 2024
This preprint is open for discussion and under review for Climate of the Past (CP).
Short summary
Short summary
We reconstruct changes in mean ocean temperature (ΔMOT) over the last 4.5 Myr. We find that the ratio of ΔMOT to changes in global mean sea surface temperature was around 0.5 before the Middle Pleistocene Transition but was 1 thereafter. We subtract our ΔMOT reconstruction from the global δ18O record to derive the δ18O of seawater. Finally, we develop a theoretical understanding of why the ratio of ΔMOT/ΔGMSST changed over the Plio-Pleistocene.
Peter Köhler and Stefan Mulitza
Clim. Past, 20, 991–1015, https://doi.org/10.5194/cp-20-991-2024, https://doi.org/10.5194/cp-20-991-2024, 2024
Short summary
Short summary
We constructed 160 kyr long mono-specific stacks of δ13C and of δ18O from the wider tropics from the planktic foraminifera G. ruber and/or T. sacculifer and compared them with carbon cycle simulations using the BICYCLE-SE model. In our stacks and our model-based interpretation, we cannot detect a species-specific isotopic fractionation during hard-shell formation as a function of carbonate chemistry in the surrounding seawater, something which is called a carbonate ion effect.
Martin Butzin, Ying Ye, Christoph Völker, Özgür Gürses, Judith Hauck, and Peter Köhler
Geosci. Model Dev., 17, 1709–1727, https://doi.org/10.5194/gmd-17-1709-2024, https://doi.org/10.5194/gmd-17-1709-2024, 2024
Short summary
Short summary
In this paper we describe the implementation of the carbon isotopes 13C and 14C into the marine biogeochemistry model FESOM2.1-REcoM3 and present results of long-term test simulations. Our model results are largely consistent with marine carbon isotope reconstructions for the pre-anthropogenic period, but also exhibit some discrepancies.
Luke Skinner, Francois Primeau, Aurich Jeltsch-Thömmes, Fortunat Joos, Peter Köhler, and Edouard Bard
Clim. Past, 19, 2177–2202, https://doi.org/10.5194/cp-19-2177-2023, https://doi.org/10.5194/cp-19-2177-2023, 2023
Short summary
Short summary
Radiocarbon is best known as a dating tool, but it also allows us to track CO2 exchange between the ocean and atmosphere. Using decades of data and novel mapping methods, we have charted the ocean’s average radiocarbon ″age” since the last Ice Age. Combined with climate model simulations, these data quantify the ocean’s role in atmospheric CO2 rise since the last Ice Age while also revealing that Earth likely received far more cosmic radiation during the last Ice Age than hitherto believed.
Claudia Hinrichs, Peter Köhler, Christoph Völker, and Judith Hauck
Biogeosciences, 20, 3717–3735, https://doi.org/10.5194/bg-20-3717-2023, https://doi.org/10.5194/bg-20-3717-2023, 2023
Short summary
Short summary
This study evaluated the alkalinity distribution in 14 climate models and found that most models underestimate alkalinity at the surface and overestimate it in the deeper ocean. It highlights the need for better understanding and quantification of processes driving alkalinity distribution and calcium carbonate dissolution and the importance of accounting for biases in model results when evaluating potential ocean alkalinity enhancement experiments.
Ying Ye, Guy Munhoven, Peter Köhler, Martin Butzin, Judith Hauck, Özgür Gürses, and Christoph Völker
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2023-181, https://doi.org/10.5194/gmd-2023-181, 2023
Revised manuscript accepted for GMD
Short summary
Short summary
Many biogeochemistry models assume all material reaching the seafloor is remineralized and returned to solution, which is sufficient for studies on short-term climate change. Under long-term climate change the storage of carbon in sediments slows down carbon cycling and influences feedbacks in the atmosphere-ocean-sediment system. Here we coupled a sediment model to an ocean biogeochemistry model and found a shift of carbon storage from the atmosphere to the ocean-sediment system.
Lennert B. Stap, Peter Köhler, and Gerrit Lohmann
Earth Syst. Dynam., 10, 333–345, https://doi.org/10.5194/esd-10-333-2019, https://doi.org/10.5194/esd-10-333-2019, 2019
Short summary
Short summary
Processes causing the same global-average radiative forcing might lead to different global temperature changes. We expand the theoretical framework by which we calculate paleoclimate sensitivity with an efficacy factor. Applying the revised approach to radiative forcing caused by CO2 and land ice albedo perturbations, inferred from data of the past 800 000 years, gives a new paleo-based estimate of climate sensitivity.
Peter Köhler, Christoph Nehrbass-Ahles, Jochen Schmitt, Thomas F. Stocker, and Hubertus Fischer
Earth Syst. Sci. Data, 9, 363–387, https://doi.org/10.5194/essd-9-363-2017, https://doi.org/10.5194/essd-9-363-2017, 2017
Short summary
Short summary
We document our best available data compilation of published ice core records of the greenhouse gases CO2, CH4, and N2O and recent measurements on firn air and atmospheric samples covering the time window from 156 000 years BP to the beginning of the year 2016 CE. A smoothing spline method is applied to translate the discrete and irregularly spaced data points into continuous time series. The radiative forcing for each greenhouse gas is computed using well-established, simple formulations.
Peter Köhler, Lennert B. Stap, Anna S. von der Heydt, Bas de Boer, and Roderik S. W. van de Wal
Clim. Past Discuss., https://doi.org/10.5194/cp-2016-23, https://doi.org/10.5194/cp-2016-23, 2016
Revised manuscript not accepted
Short summary
Short summary
Evidence indicate that specific equilibrium climate sensitivity, the global annual mean surface temperature change as a response to a change in radiative forcing, is state dependent. We here show that the interpretation of data in the state-dependent case is not straightforward. We analyse the differences of a point-wise approach and one based on a piece-wise linear analysis, combine both, compare with potential model results and apply the theoretical concepts to data of the last 800 kyr.
P. Köhler, B. de Boer, A. S. von der Heydt, L. B. Stap, and R. S. W. van de Wal
Clim. Past, 11, 1801–1823, https://doi.org/10.5194/cp-11-1801-2015, https://doi.org/10.5194/cp-11-1801-2015, 2015
Short summary
Short summary
We find that the specific equilibrium climate sensitivity due to radiative forcing of CO2 and land ice albedo has been state-dependent for the last 2.1Myr (most of the Pleistocene). Its value is ~45% larger during intermediate glaciated climates and interglacial periods than during Pleistocene full glacial conditions. The state dependency is mainly caused by a latitudinal dependency in ice sheet area changes. Due to uncertainties in CO2, firm conclusions for the Pliocene are not yet possible.
R. Schneider, J. Schmitt, P. Köhler, F. Joos, and H. Fischer
Clim. Past, 9, 2507–2523, https://doi.org/10.5194/cp-9-2507-2013, https://doi.org/10.5194/cp-9-2507-2013, 2013
R. S. W. van de Wal, B. de Boer, L. J. Lourens, P. Köhler, and R. Bintanja
Clim. Past, 7, 1459–1469, https://doi.org/10.5194/cp-7-1459-2011, https://doi.org/10.5194/cp-7-1459-2011, 2011
P. Köhler, G. Knorr, D. Buiron, A. Lourantou, and J. Chappellaz
Clim. Past, 7, 473–486, https://doi.org/10.5194/cp-7-473-2011, https://doi.org/10.5194/cp-7-473-2011, 2011
P. Köhler and A. Huth
Biogeosciences, 7, 2531–2543, https://doi.org/10.5194/bg-7-2531-2010, https://doi.org/10.5194/bg-7-2531-2010, 2010
P. Köhler
Clim. Past Discuss., https://doi.org/10.5194/cpd-6-1453-2010, https://doi.org/10.5194/cpd-6-1453-2010, 2010
Revised manuscript has not been submitted
P. Köhler, H. Fischer, J. Schmitt, and G. Munhoven
Biogeosciences, 3, 539–556, https://doi.org/10.5194/bg-3-539-2006, https://doi.org/10.5194/bg-3-539-2006, 2006
P. Köhler and H. Fischer
Clim. Past, 2, 57–78, https://doi.org/10.5194/cp-2-57-2006, https://doi.org/10.5194/cp-2-57-2006, 2006