Articles | Volume 13, issue 3
https://doi.org/10.5194/esd-13-1041-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/esd-13-1041-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
04 Jul 2022
Research article |
| 04 Jul 2022
| 04 Jul 2022
Effect of the Atlantic Meridional Overturning Circulation on atmospheric pCO2 variations
Institute for Marine and Atmospheric research Utrecht, Department of Physics, Utrecht University, Utrecht, the Netherlands
Anna S. von der Heydt
Institute for Marine and Atmospheric research Utrecht, Department of Physics, Utrecht University, Utrecht, the Netherlands
Center for Complex Systems Studies, Utrecht University, Utrecht, the Netherlands
Henk A. Dijkstra
Institute for Marine and Atmospheric research Utrecht, Department of Physics, Utrecht University, Utrecht, the Netherlands
Center for Complex Systems Studies, Utrecht University, Utrecht, the Netherlands
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Clim. Past, 17, 2427–2450, https://doi.org/10.5194/cp-17-2427-2021, https://doi.org/10.5194/cp-17-2427-2021, 2021
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In this work, we have studied the behaviour of El Niño events in the mid-Pliocene, a period of around 3 million years ago, using a collection of 17 climate models. It is an interesting period to study, as it saw similar atmospheric carbon dioxide levels to the present day. We find that the El Niño events were less strong in the mid-Pliocene simulations, when compared to pre-industrial climate. Our results could help to interpret El Niño behaviour in future climate projections.
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Ocean Sci., 17, 1251–1271, https://doi.org/10.5194/os-17-1251-2021, https://doi.org/10.5194/os-17-1251-2021, 2021
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Ellen Berntell, Qiong Zhang, Qiang Li, Alan M. Haywood, Julia C. Tindall, Stephen J. Hunter, Zhongshi Zhang, Xiangyu Li, Chuncheng Guo, Kerim H. Nisancioglu, Christian Stepanek, Gerrit Lohmann, Linda E. Sohl, Mark A. Chandler, Ning Tan, Camille Contoux, Gilles Ramstein, Michiel L. J. Baatsen, Anna S. von der Heydt, Deepak Chandan, William Richard Peltier, Ayako Abe-Ouchi, Wing-Le Chan, Youichi Kamae, Charles J. R. Williams, Daniel J. Lunt, Ran Feng, Bette L. Otto-Bliesner, and Esther C. Brady
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Earth Syst. Dynam., 12, 819–835, https://doi.org/10.5194/esd-12-819-2021, https://doi.org/10.5194/esd-12-819-2021, 2021
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Tipping of one climate subsystem could trigger a cascade of subsequent tipping points and even global-scale climate tipping. Sequential shifts of atmosphere, sea ice and ocean have been recorded in proxy archives of past climate change. Based on this we propose a conceptual model for abrupt climate changes of the last glacial. Here, rate-induced tipping enables tipping cascades in systems with relatively weak coupling. An early warning signal is proposed that may detect such a tipping.
André Jüling, Xun Zhang, Daniele Castellana, Anna S. von der Heydt, and Henk A. Dijkstra
Ocean Sci., 17, 729–754, https://doi.org/10.5194/os-17-729-2021, https://doi.org/10.5194/os-17-729-2021, 2021
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We investigate how the freshwater budget of the Atlantic changes under climate change, which has implications for the stability of the Atlantic Meridional Overturning Circulation. We compare the effect of ocean model resolution in a climate model and find many similarities between the simulations, enhancing trust in the current generation of climate models. However, ocean biases are reduced in the strongly eddying simulation, and significant local freshwater budget differences exist.
Zhongshi Zhang, Xiangyu Li, Chuncheng Guo, Odd Helge Otterå, Kerim H. Nisancioglu, Ning Tan, Camille Contoux, Gilles Ramstein, Ran Feng, Bette L. Otto-Bliesner, Esther Brady, Deepak Chandan, W. Richard Peltier, Michiel L. J. Baatsen, Anna S. von der Heydt, Julia E. Weiffenbach, Christian Stepanek, Gerrit Lohmann, Qiong Zhang, Qiang Li, Mark A. Chandler, Linda E. Sohl, Alan M. Haywood, Stephen J. Hunter, Julia C. Tindall, Charles Williams, Daniel J. Lunt, Wing-Le Chan, and Ayako Abe-Ouchi
Clim. Past, 17, 529–543, https://doi.org/10.5194/cp-17-529-2021, https://doi.org/10.5194/cp-17-529-2021, 2021
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The Atlantic Meridional Overturning Circulation (AMOC) is an important topic in the Pliocene Model Intercomparison Project. Previous studies have suggested a much stronger AMOC during the Pliocene than today. However, our current multi-model intercomparison shows large model spreads and model–data discrepancies, which can not support the previous hypothesis. Our study shows good consistency with future projections of the AMOC.
Pascal Wang, Daniele Castellana, and Henk A. Dijkstra
Nonlin. Processes Geophys., 28, 135–151, https://doi.org/10.5194/npg-28-135-2021, https://doi.org/10.5194/npg-28-135-2021, 2021
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This paper proposes two improvements to the use of Trajectory-Adaptive Multilevel Sampling, a rare-event algorithm which computes noise-induced transition probabilities. The first improvement uses locally linearised dynamics in order to reduce the arbitrariness associated with defining what constitutes a transition. The second improvement uses empirical transition paths accumulated at high noise in order to formulate the score function which determines the performance of the algorithm.
Amber Boot, René M. van Westen, and Henk A. Dijkstra
Ocean Sci., 17, 335–350, https://doi.org/10.5194/os-17-335-2021, https://doi.org/10.5194/os-17-335-2021, 2021
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The Maud Rise polynya is a hole in the sea ice surrounding Antarctica that occurs during winter. It appeared in 2016 and 2017. Our study concludes that heat and salt accumulation around 1000 m depth are likely to be important for polynya formation. The heat is mixed upward to the surface where it is able to melt the sea ice and, thus, create a polynya. How often the polynya forms depends largely on the variation in the time of the heat and salt accumulation.
David K. Hutchinson, Helen K. Coxall, Daniel J. Lunt, Margret Steinthorsdottir, Agatha M. de Boer, Michiel Baatsen, Anna von der Heydt, Matthew Huber, Alan T. Kennedy-Asser, Lutz Kunzmann, Jean-Baptiste Ladant, Caroline H. Lear, Karolin Moraweck, Paul N. Pearson, Emanuela Piga, Matthew J. Pound, Ulrich Salzmann, Howie D. Scher, Willem P. Sijp, Kasia K. Śliwińska, Paul A. Wilson, and Zhongshi Zhang
Clim. Past, 17, 269–315, https://doi.org/10.5194/cp-17-269-2021, https://doi.org/10.5194/cp-17-269-2021, 2021
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The Eocene–Oligocene transition was a major climate cooling event from a largely ice-free world to the first major glaciation of Antarctica, approximately 34 million years ago. This paper reviews observed changes in temperature, CO2 and ice sheets from marine and land-based records at this time. We present a new model–data comparison of this transition and find that CO2-forced cooling provides the best explanation of the observed global temperature changes.
David Wichmann, Christian Kehl, Henk A. Dijkstra, and Erik van Sebille
Nonlin. Processes Geophys., 28, 43–59, https://doi.org/10.5194/npg-28-43-2021, https://doi.org/10.5194/npg-28-43-2021, 2021
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Fluid parcels transported in complicated flows often contain subsets of particles that stay close over finite time intervals. We propose a new method for detecting finite-time coherent sets based on the density-based clustering technique of ordering points to identify the clustering structure (OPTICS). Unlike previous methods, our method has an intrinsic notion of coherent sets at different spatial scales. OPTICS is readily implemented in the SciPy sklearn package, making it easy to use.
Carine G. van der Boog, J. Otto Koetsier, Henk A. Dijkstra, Julie D. Pietrzak, and Caroline A. Katsman
Earth Syst. Sci. Data, 13, 43–61, https://doi.org/10.5194/essd-13-43-2021, https://doi.org/10.5194/essd-13-43-2021, 2021
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Thermohaline staircases are stepped structures in the ocean that contain enhanced diapycnal salt and heat transport. In this study, we present a global dataset of thermohaline staircases derived from 487 493 observations of Argo profiling floats and Ice-Tethered Profilers using a novel detection algorithm.
Michiel Baatsen, Anna S. von der Heydt, Matthew Huber, Michael A. Kliphuis, Peter K. Bijl, Appy Sluijs, and Henk A. Dijkstra
Clim. Past, 16, 2573–2597, https://doi.org/10.5194/cp-16-2573-2020, https://doi.org/10.5194/cp-16-2573-2020, 2020
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Warm climates of the deep past have proven to be challenging to reconstruct with the same numerical models used for future predictions. We present results of CESM simulations for the middle to late Eocene (∼ 38 Ma), in which we managed to match the available indications of temperature well. With these results we can now look into regional features and the response to external changes to ultimately better understand the climate when it is in such a warm state.
René M. van Westen and Henk A. Dijkstra
Ocean Sci., 16, 1443–1457, https://doi.org/10.5194/os-16-1443-2020, https://doi.org/10.5194/os-16-1443-2020, 2020
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During the mid-1970s and quite recently in 2017, a large open-water area appeared in the Antarctic sea-ice pack, the so-called Maud Rise polynya. From several model studies, the reoccurrence time of this polynya seems arbitrary. In this study, we address the reoccurrence time of the polynya using a high-resolution climate model. We find a preferred multidecadal return time in polynya formation. The return time of the polynya is associated with a large-scale ocean mode in the Southern Ocean.
Wesley de Nooijer, Qiong Zhang, Qiang Li, Qiang Zhang, Xiangyu Li, Zhongshi Zhang, Chuncheng Guo, Kerim H. Nisancioglu, Alan M. Haywood, Julia C. Tindall, Stephen J. Hunter, Harry J. Dowsett, Christian Stepanek, Gerrit Lohmann, Bette L. Otto-Bliesner, Ran Feng, Linda E. Sohl, Mark A. Chandler, Ning Tan, Camille Contoux, Gilles Ramstein, Michiel L. J. Baatsen, Anna S. von der Heydt, Deepak Chandan, W. Richard Peltier, Ayako Abe-Ouchi, Wing-Le Chan, Youichi Kamae, and Chris M. Brierley
Clim. Past, 16, 2325–2341, https://doi.org/10.5194/cp-16-2325-2020, https://doi.org/10.5194/cp-16-2325-2020, 2020
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The simulations for the past climate can inform us about the performance of climate models in different climate scenarios. Here, we analyse Arctic warming in an ensemble of 16 simulations of the mid-Pliocene Warm Period (mPWP), when the CO2 level was comparable to today. The results highlight the importance of slow feedbacks in the model simulations and imply that we must be careful when using simulations of the mPWP as an analogue for future climate change.
David Wichmann, Christian Kehl, Henk A. Dijkstra, and Erik van Sebille
Nonlin. Processes Geophys., 27, 501–518, https://doi.org/10.5194/npg-27-501-2020, https://doi.org/10.5194/npg-27-501-2020, 2020
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The surface transport of heat, nutrients and plastic in the North Atlantic Ocean is organized into large-scale flow structures. We propose a new and simple method to detect such features in ocean drifter data sets by identifying groups of trajectories with similar dynamical behaviour using network theory. We successfully detect well-known regions such as the Subpolar and Subtropical gyres, the Western Boundary Current region and the Caribbean Sea.
Alan M. Haywood, Julia C. Tindall, Harry J. Dowsett, Aisling M. Dolan, Kevin M. Foley, Stephen J. Hunter, Daniel J. Hill, Wing-Le Chan, Ayako Abe-Ouchi, Christian Stepanek, Gerrit Lohmann, Deepak Chandan, W. Richard Peltier, Ning Tan, Camille Contoux, Gilles Ramstein, Xiangyu Li, Zhongshi Zhang, Chuncheng Guo, Kerim H. Nisancioglu, Qiong Zhang, Qiang Li, Youichi Kamae, Mark A. Chandler, Linda E. Sohl, Bette L. Otto-Bliesner, Ran Feng, Esther C. Brady, Anna S. von der Heydt, Michiel L. J. Baatsen, and Daniel J. Lunt
Clim. Past, 16, 2095–2123, https://doi.org/10.5194/cp-16-2095-2020, https://doi.org/10.5194/cp-16-2095-2020, 2020
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The large-scale features of middle Pliocene climate from the 16 models of PlioMIP Phase 2 are presented. The PlioMIP2 ensemble average was ~ 3.2 °C warmer and experienced ~ 7 % more precipitation than the pre-industrial era, although there are large regional variations. PlioMIP2 broadly agrees with a new proxy dataset of Pliocene sea surface temperatures. Combining PlioMIP2 and proxy data suggests that a doubling of atmospheric CO2 would increase globally averaged temperature by 2.6–4.8 °C.
Erin L. McClymont, Heather L. Ford, Sze Ling Ho, Julia C. Tindall, Alan M. Haywood, Montserrat Alonso-Garcia, Ian Bailey, Melissa A. Berke, Kate Littler, Molly O. Patterson, Benjamin Petrick, Francien Peterse, A. Christina Ravelo, Bjørg Risebrobakken, Stijn De Schepper, George E. A. Swann, Kaustubh Thirumalai, Jessica E. Tierney, Carolien van der Weijst, Sarah White, Ayako Abe-Ouchi, Michiel L. J. Baatsen, Esther C. Brady, Wing-Le Chan, Deepak Chandan, Ran Feng, Chuncheng Guo, Anna S. von der Heydt, Stephen Hunter, Xiangyi Li, Gerrit Lohmann, Kerim H. Nisancioglu, Bette L. Otto-Bliesner, W. Richard Peltier, Christian Stepanek, and Zhongshi Zhang
Clim. Past, 16, 1599–1615, https://doi.org/10.5194/cp-16-1599-2020, https://doi.org/10.5194/cp-16-1599-2020, 2020
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We examine the sea-surface temperature response to an interval of climate ~ 3.2 million years ago, when CO2 concentrations were similar to today and the near future. Our geological data and climate models show that global mean sea-surface temperatures were 2.3 to 3.2 ºC warmer than pre-industrial climate, that the mid-latitudes and high latitudes warmed more than the tropics, and that the warming was particularly enhanced in the North Atlantic Ocean.
Cited articles
Archer, D., Kheshgi, H., and Maier-Reimer, E.: Multiple timescales for
neutralization of fossil fuel CO2, Geophys. Res. Lett., 24,
405–408, https://doi.org/10.1029/97GL00168, 1997. a, b
Bakker, P., Schmittner, A., Lenaerts, J. T. M., Abe-Ouchi, A., Bi, D., van den Broeke, M. R., Chan, W.-L., Hu, A., Beadling, R. L., Marsland, S. J.,
Mernild, S. H., Saenko, O. A., Swingedouw, D., Sullivan, A., and Yin, J.: Fate of the Atlantic Meridional Overturning Circulation: Strong decline
under continued warming and Greenland melting, Geophys. Res. Lett., 43, 12252–12260, https://doi.org/10.1002/2016GL070457, 2016. a
Barker, S. and Elderfield, H.: Foraminiferal Calcification Response to
Glacial-Interglacial Changes in Atmospheric CO2, Science, 297, 833–836, https://doi.org/10.1126/science.1072815, 2002. a
Bauska, T. K., Marcott, S. A., and Brook, E. J.: Abrupt changes in the global carbon cycle during the last glacial period, Nat. Geosci., 14, 91–96,
https://doi.org/10.1038/s41561-020-00680-2, 2021. a
Boot, D., Von der Heydt, A. S., and Dijkstra, H. A.: SCPM-AUTO-ESD,
Zenodo [code and data set], https://doi.org/10.5281/zenodo.4972553, 2021. a
Cael, B. B., Bisson, K., and Follows, M. J.: How have recent temperature
changes affected the efficiency of ocean biological carbon export?, Limnol. Oceanogr. Lett., 2, 113–118, https://doi.org/10.1002/lol2.10042, 2017. a
Cole, C., Finch, A. A., Hintz, C., Hintz, K., and Allison, N.: Effects of
seawater pCO2 and temperature on calcification and productivity in the coral genus Porites spp.: an exploration of potential interaction mechanisms, Coral Reefs, 37, 471–481, https://doi.org/10.1007/s00338-018-1672-3, 2018. a
Doedel, E. J., Paffenroth, R. C., Champneys, A. C., Fairgrieve, T. F.,
Kuznetsov, Y. A., Oldeman, B. E., Sandstede, B., and Wang, X. J.: AUTO-07p:
Continuation and Bifurcation Software for Ordinary Differential Equations,
https://www.macs.hw.ac.uk/~gabriel/auto07/auto.html (last access: 27 June 2022), 2007. a
Doedel, E. J., Paffenroth, R. C., Champneys, A. C., Fairgrieve, T. F., Kuznetsov, Y. A., Oldeman, B. E., Sandstede, B., and Wang, X. J.:
AUTO-07p, https://sourceforge.net/projects/auto-07p/, last access: 27 June 2022. a
Duplessy, J. C., Shackleton, N. J., Fairbanks, R. G., Labeyrie, L., Oppo, D.,
and Kallel, N.: Deepwater source variations during the last climatic cycle
and their impact on the global deepwater circulation, Paleoceanography, 3,
343–360, https://doi.org/10.1029/PA003i003p00343, 1988. a
Follows, M. J., Ito, T., and Dutkiewicz, S.: On the solution of the carbonate chemistry system in ocean biogeochemistry models, Ocean Model., 12, 290–301, https://doi.org/10.1016/j.ocemod.2005.05.004, 2006. a, b
Friedlingstein, P., O'Sullivan, M., Jones, M. W., Andrew, R. M., Hauck, J.,
Olsen, A., Peters, G. P., Peters, W., Pongratz, J., Sitch, S., Le Quéré, C., Canadell, J. G., Ciais, P., Jackson, R. B., Alin, S.,
Aragão, L. E. O. C., Arneth, A., Arora, V., Bates, N. R., Becker, M.,
Benoit-Cattin, A., Bittig, H. C., Bopp, L., Bultan, S., Chandra, N.,
Chevallier, F., Chini, L. P., Evans, W., Florentie, L., Forster, P. M.,
Gasser, T., Gehlen, M., Gilfillan, D., Gkritzalis, T., Gregor, L., Gruber,
N., Harris, I., Hartung, K., Haverd, V., Houghton, R. A., Ilyina, T., Jain,
A. K., Joetzjer, E., Kadono, K., Kato, E., Kitidis, V., Korsbakken, J. I.,
Landschützer, P., Lefèvre, N., Lenton, A., Lienert, S., Liu, Z.,
Lombardozzi, D., Marland, G., Metzl, N., Munro, D. R., Nabel, J. E. M. S.,
Nakaoka, S.-I., Niwa, Y., O'Brien, K., Ono, T., Palmer, P. I., Pierrot, D.,
Poulter, B., Resplandy, L., Robertson, E., Rödenbeck, C., Schwinger,
J., Séférian, R., Skjelvan, I., Smith, A. J. P., Sutton, A. J., Tanhua, T., Tans, P. P., Tian, H., Tilbrook, B., van der Werf, G., Vuichard,
N., Walker, A. P., Wanninkhof, R., Watson, A. J., Willis, D., Wiltshire, A. J., Yuan, W., Yue, X., and Zaehle, S.: Global Carbon Budget 2020, Earth
Syst. Sci. Data, 12, 3269–3340, https://doi.org/10.5194/essd-12-3269-2020, 2020. a
Ganachaud, A. and Wunsch, C.: Improved estimates of global ocean circulation, heat transport and mixing from hydrographic data, Nature, 408, 453–457,
https://doi.org/10.1038/35044048, 2000. a
Gottschalk, J., Battaglia, G., Fischer, H., Frölicher, T. L., Jaccard,
S. L., Jeltsch-Thömmes, A., Joos, F., Köhler, P., Meissner, K. J., Menviel, L., Nehrbass-Ahles, C., Schmitt, J., Schmittner, A., Skinner, L. C., and Stocker, T. F.: Mechanisms of millennial-scale atmospheric CO2
change in numerical model simulations, Quaternary Sci. Rev., 220, 30–74, https://doi.org/10.1016/j.quascirev.2019.05.013, 2019. a, b
Gregory, J. M., Dixon, K. W., Stouffer, R. J., Weaver, A. J., Driesschaert, E., Eby, M., Fichefet, T., Hasumi, H., Hu, A., Jungclaus, J. H., Kamenkovich,
I. V., Levermann, A., Montoya, M., Murakami, S., Nawrath, S., Oka, A.,
Sokolov, A. P., and Thorpe, R. B.: A model intercomparison of changes in the
Atlantic thermohaline circulation in response to increasing atmospheric CO2 concentration, Geophys. Res. Lett., 32, L12703, https://doi.org/10.1029/2005GL023209, 2005. a
Gruber, N., Landschützer, P., and Lovenduski, N. S.: The Variable
Southern Ocean Carbon Sink, Annu. Rev. Mar. Sci., 11, 159–186,
https://doi.org/10.1146/annurev-marine-121916-063407, 2019. a
Huiskamp, W. N. and Meissner, K. J.: Oceanic carbon and water masses during
the Mystery Interval: A model-data comparison study, Paleoceanography, 27,
PA4206, https://doi.org/10.1029/2012PA002368, 2012. a
Jiang, X. and Yung, Y. L.: Global Patterns of Carbon Dioxide Variability from Satellite Observations, Annu. Rev. Earth Planet. Sci., 47, 225–245, https://doi.org/10.1146/annurev-earth-053018-060447, 2019. a
Kwon, E. Y. and Primeau, F.: Optimization and sensitivity of a global
biogeochemistry ocean model using combined in situ DIC, alkalinity, and
phosphate data, J. Geophys. Res.-Oceans, 113, C08011, https://doi.org/10.1029/2007JC004520, 2008. a
Lueker, T. J., Dickson, A. G., and Keeling, C. D.: Ocean pCO2 calculated from dissolved inorganic carbon, alkalinity, and equations for K1 and K2: validation based on laboratory measurements of CO2 in gas and seawater at
equilibrium, Mar. Chem., 70, 105–119, https://doi.org/10.1016/S0304-4203(00)00022-0, 2000. a, b
Marchal, O., Stocker, T. F., and Joos, F.: Impact of oceanic reorganizations
on the ocean carbon cycle and atmospheric carbon dioxide content,
Paleoceanography, 13, 225–244, https://doi.org/10.1029/98PA00726, 1998. a
Mariotti, V., Bopp, L., Tagliabue, A., Kageyama, M., and Swingedouw, D.:
Marine productivity response to Heinrich events: a model-data comparison,
Clim. Past, 8, 1581–1598, https://doi.org/10.5194/cp-8-1581-2012, 2012. a
Martin, J. H., Knauer, G. A., Karl, D. M., and Broenkow, W. W.: VERTEX: carbon cycling in the northeast Pacific, Deep-Sea Res, Pt. A, 34, 267–285,
https://doi.org/10.1016/0198-0149(87)90086-0, 1987. a
Menviel, L., Timmermann, A., Mouchet, A., and Timm, O.: Meridional
reorganizations of marine and terrestrial productivity during Heinrich
events, Paleoceanography, 23, PA1203, https://doi.org/10.1029/2007PA001445, 2008. a
Menviel, L., England, M. H., Meissner, K. J., Mouchet, A., and Yu, J.:
Atlantic-Pacific seesaw and its role in outgassing CO2 during Heinrich events, Paleoceanography, 29, 58–70, https://doi.org/10.1002/2013PA002542, 2014. a, b
Millero, F. J.: Chapter 43 – Influence of Pressure on Chemical Processes in
the Sea, Academic Press, 1–88, https://doi.org/10.1016/B978-0-12-588608-6.50007-9, 1983. a
Mucci, A.: The solubility of calcite and aragonite in seawater at various
salinities, temperatures, and one atmosphere total pressure, Am. J. Sci., 283, 780–799, https://doi.org/10.2475/ajs.283.7.780, 1983. a
Muller, R. A. and MacDonald, G. J.: Ice Ages and Astronomical Causes,
Springer-Verlag, ISBN 978-3-540-43779-6, 2000. a
Munday, D. R., Johnson, H. L., and P, M. D.: Impacts and effects of mesoscale ocean eddies on ocean carbon storage and atmospheric pCO2, Global Biogeochem. Cy., 28, 877–896, https://doi.org/10.1002/2014GB004836, 2014. a
Munhoven, G.: Mathematics of the total alkalinity–pH equation – pathway to
robust and universal solution algorithms: the SolveSAPHE package v1.0.1
Geosci. Model Dev., 6, 1367–1388, https://doi.org/10.5194/gmd-6-1367-2013, 2013. a, b, c, d
Nielsen, S. B., Jochum, M., Pedro, J. B., Eden, C., and Nuterman, R.:
Two-Timescale Carbon Cycle Response to an AMOC Collapse, Paleoceanogr. Paleocl., 34, 511–523, https://doi.org/10.1029/2018PA003481, 2019. a, b
O'Neill, C. M., Hogg, A. M., Ellwood, M. J., Opdyke, B. N., and Eggins, S. M.: [simple carbon project] model (V1.0), Zenodo [code], https://doi.org/10.5281/zenodo.1310161, 2018. a
Petit, J. R., Jouzel, J., Raynaud, D., Barkov, N. I., Barnola, J.-M., Basile,
I., Bender, M., Chappellaz, J., Davis, M., Delaygue, G., Delmotte, M.,
Kotlyakov, V. M., Legrand, M., Lipenkov, V. Y., Lorius, C., Pépin, L.,
Ritz, C., Saltzman, E., and Stievenard, M.: Climate and atmospheric history
of the past 420,000 years from the Vostok ice core, Antarctica, Nature, 399,
429–436, https://doi.org/10.1038/20859, 1999. a
Ridgwell, A., Hargreaves, J. C., Edwards, N. R., Annan, J. D., Lenton, T. M.,
Marsh, R., Yool, A., and Watson, A.: Marine geochemical data assimilation in
an efficient Earth System Model of global biogeochemical cycling,
Biogeosciences, 4, 87–104, https://doi.org/10.5194/bg-4-87-2007, 2007. a
Rothman, D. H.: Earth's carbon cycle: A mathematical perspective, B. Am. Math. Soc., 52, 47–64, https://doi.org/10.1090/S0273-0979-2014-01471-5, 2015. a
Sabine, C. L., Feely, R. A., Gruber, N., Key, R. M., Lee, K., Bullister, J. L., Wanninkhof, R., Wong, C. S., Wallace, D. W. R., Tilbrook, B., Millero, F. J., Peng, T.-H., Kozyr, A., Ono, T., and Rios, A. F.: The Oceanic Sink for
Anthropogenic CO2, Science, 305, 367–371, https://doi.org/10.1126/science.1097403, 2004. a
Sarmiento, J. L. . and Gruber, N. .: Ocean biogeochemical dynamics, xii, 503 pages, 8 pages of plates: illustrations (some color), maps (some color); 29 cm, Princeton University Press, Princeton, SE, ISBN 978-0-691-01707-5, 2006. a
Schmittner, A., Brook, E. J., and Ahn, J.: Impact of the ocean's Overturning circulation on atmospheric CO2, in: Ocean Circulation: Mechanisms and Impacts – Past and Future Changes of Meridional Overturning, edited by: Schmittner, A., Chiang, J. C. H., and Hemming, S. R., Wiley, https://doi.org/10.1029/173GM20, 2007. a
Talley, L. D.: Closure of the Global Overturning Circulation Through the
Indian, Pacific, and Southern Oceans: Schematics and Transports,
Oceanography, 26, 80–97, https://doi.org/10.5670/oceanog.2013.07, 2013. a
Toggweiler, J. R. and Russell, J.: Ocean circulation in a warming climate,
Nature, 451, 286–288, https://doi.org/10.1038/nature06590, 2008. a, b
Vellinga, M. and Wood, R. A.: Global Climatic Impacts of a Collapse of the
Atlantic Thermohaline Circulation, Climatic Change, 54, 251–267,
https://doi.org/10.1023/A:1016168827653, 2002.
a
Walker, J. C. and Kasting, J. F.: Effects of fuel and forest conservation on future levels of atmospheric carbon dioxide, Global Planet. Change, 97, 151–189, 1992. a
Wanninkhof, R.: Relationship between wind speed and gas exchange over the
ocean, J. Geophys. Res.-Oceans, 97, 7373–7382, https://doi.org/10.1029/92JC00188, 1992. a
Weijer, W., Cheng, W., Drijfhout, S. S., Fedorov, A. V., Hu, A., Jackson,
L. C., Liu, W., McDonagh, E. L., Mecking, J. V., and Zhang, J.: Stability of
the Atlantic Meridional Overturning Circulation: A Review and Synthesis, J. Geophys. Res.-Oceans, 124, 5336–5375, https://doi.org/10.1029/2019JC015083, 2019. a, b
Weijer, W., Cheng, W., Garuba, O. A., Hu, A., and Nadiga, B. T.: CMIP6 Models Predict Significant 21st Century Decline of the Atlantic Meridional
Overturning Circulation, Geophys. Res. Lett., 47, e2019GL086075,
https://doi.org/10.1029/2019GL086075, 2020. a
Weiss, R. F.: Carbon dioxide in water and seawater: the solubility of a
non-ideal gas, Mar. Chem., 2, 203–215, https://doi.org/10.1016/0304-4203(74)90015-2, 1974. a
Williams, R. G. and Follows, M. J.: Ocean Dynamics and the Carbon Cycle:
Principles and Mechanisms, Cambridge University Press, Cambridge, https://doi.org/10.1017/CBO9780511977817, 2011. a
Zeebe, R. E.: LOSCAR: Long-term Ocean-atmosphere-Sediment CArbon cycle
Reservoir Model v2.0.4, Geosci. Model Dev., 5, 149–166,
https://doi.org/10.5194/gmd-5-149-2012, 2012. a
Zeebe, R. E. and Westbroek, P.: A simple model for the CaCO3 saturation state of the ocean: The “Strangelove”, the “Neritan”, and the “Cretan” Ocean, Geochem. Geophy. Geosy., 4, 1104, https://doi.org/10.1029/2003GC000538, 2003. a
Zelinka, M. D., Myers, T. A., McCoy, D. T., Po-Chedley, S., Caldwell, P. M.,
Ceppi, P., Klein, S. A., and Taylor, K. E.: Causes of Higher Climate
Sensitivity in CMIP6 Models, Geophys. Res. Lett., 47, e2019GL085782, https://doi.org/10.1029/2019GL085782, 2020. a, b
Zhu, J., Liu, Z., Zhang, J., and Liu, W.: AMOC response to global warming:
dependence on the background climate and response timescale, Clim. Dynam., 44, 3449–3468, https://doi.org/10.1007/s00382-014-2165-x, 2015. a
Short summary
Atmospheric pCO2 of the past shows large variability on different timescales. We focus on the effect of the strength of Atlantic Meridional Overturning Circulation (AMOC) on this variability and on the AMOC–pCO2 relationship. We find that climatic boundary conditions and the representation of biology in our model are most important for this relationship. Under certain conditions, we find internal oscillations, which can be relevant for atmospheric pCO2 variability during glacial cycles.
Atmospheric pCO2 of the past shows large variability on different timescales. We focus on the...
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