Distinct roles of the Southern Ocean and North Atlantic in the deglacial atmospheric radiocarbon decline

Hain, Mathis P.; Sigman, Daniel M.; Haug, Gerald H.

doi:10.1016/j.epsl.2014.03.020

Cited by 62 publications

(134 citation statements)

References 88 publications

Supporting

Mentioning

125

Contrasting

Order By: Relevance

“…Modification of the terrestrial carbon cycle components is described in detail in the Appendix. For simulation of atmospheric radiocarbon during the last glacial termination we used the rate of 14 C production following the scenario of Hain et al (2014), which is based on the production model of Kovaltsov et al (2012).…”

Section: Climber-2 Model Descriptionmentioning

confidence: 99%

Simulation of climate, ice sheets and CO<sub>2</sub> evolution during the last four glacial cycles with an Earth system model of intermediate complexity

2017

View full text Add to dashboard Cite

Abstract. In spite of significant progress in paleoclimate reconstructions and modelling of different aspects of the past glacial cycles, the mechanisms which transform regional and seasonal variations in solar insolation into long-term and global-scale glacial-interglacial cycles are still not fully understood -in particular, in relation to CO 2 variability. Here using the Earth system model of intermediate complexity CLIMBER-2 we performed simulations of the coevolution of climate, ice sheets, and carbon cycle over the last 400 000 years using the orbital forcing as the only external forcing. The model simulates temporal dynamics of CO 2 , global ice volume, and other climate system characteristics in good agreement with paleoclimate reconstructions. These results provide strong support for the idea that long and strongly asymmetric glacial cycles of the late Quaternary represent a direct but strongly nonlinear response of the Northern Hemisphere ice sheets to orbital forcing. This response is strongly amplified and globalised by the carbon cycle feedbacks. Using simulations performed with the model in different configurations, we also analyse the role of individual processes and sensitivity to the choice of model parameters. While many features of simulated glacial cycles are rather robust, some details of CO 2 evolution, especially during glacial terminations, are sensitive to the choice of model parameters. Specifically, we found two major regimes of CO 2 changes during terminations: in the first one, when the recovery of the Atlantic meridional overturning circulation (AMOC) occurs only at the end of the termination, a pronounced overshoot in CO 2 concentration occurs at the beginning of the interglacial and CO 2 remains almost constant during the interglacial or even declines towards the end, resembling Eemian CO 2 dynamics. However, if the recovery of the AMOC occurs in the middle of the glacial termination, CO 2 concentration continues to rise during the interglacial, similar to the Holocene. We also discuss the potential contribution of the brine rejection mechanism for the CO 2 and carbon isotopes in the atmosphere and the ocean during the past glacial termination.

show abstract

Section: Climber-2 Model Descriptionmentioning

confidence: 99%

Simulation of climate, ice sheets and CO<sub>2</sub> evolution during the last four glacial cycles with an Earth system model of intermediate complexity

2017

View full text Add to dashboard Cite

show abstract

“…Apart from atmospheric CO 2 itself and the release of deep ocean waters, 14 C is strongly influenced by the cosmogenic production rate of 14 C. This production rate is determined with rather large uncertainties and there are different ways to derive it. In the Supplement, we present the three 14 C production rate time series of the studies by Laj et al (2004), Muscheler et al (2004) and Hain et al (2014) across the last 25 kyr BP. Here, we present an evaluation of the three 14 C production rate data applied to the ALL_TF simulation.…”

Section: Transient Simulation Resultsmentioning

confidence: 99%

“…To generate LGM conditions for 14 C in atmosphere and ocean, we applied the average cosmogenic 14 C production rate from 25 to 26 ka BP (PR14 C = 2.1 × 10 4 atoms cm −2 s −1 ). For this and in most of the transient simulations, we use the most recent production rate time series developed by Hain et al (2014). In a sensitivity analysis, the 14 C production rates from the studies by Laj et al (2004) and Muscheler et al (2004) are applied as well.…”

Section: Model Lgm and Transitionmentioning

confidence: 99%

An improved land biosphere module for use in the DCESS Earth system model (version 1.1) with application to the last glacial termination

et al. 2017

View full text Add to dashboard Cite

Abstract. Interactions between the land biosphere and the atmosphere play an important role for the Earth's carbon cycle and thus should be considered in studies of global carbon cycling and climate. Simple approaches are a useful first step in this direction but may not be applicable for certain climatic conditions. To improve the ability of the reduced-complexity Danish Center for Earth System Science (DCESS) Earth system model DCESS to address cold climate conditions, we reformulated the model's land biosphere module by extending it to include three dynamically varying vegetation zones as well as a permafrost component. The vegetation zones are formulated by emulating the behaviour of a complex land biosphere model. We show that with the new module, the size and timing of carbon exchanges between atmosphere and land are represented more realistically in cooling and warming experiments. In particular, we use the new module to address carbon cycling and climate change across the last glacial transition. Within the constraints provided by various proxy data records, we tune the DCESS model to a Last Glacial Maximum state and then conduct transient sensitivity experiments across the transition under the application of explicit transition functions for high-latitude ocean exchange, atmospheric dust, and the land ice sheet extent. We compare simulated time evolutions of global mean temperature, pCO 2 , atmospheric and oceanic carbon isotopes as well as ocean dissolved oxygen concentrations with proxy data records. In this way we estimate the importance of different processes across the transition with emphasis on the role of land biosphere variations and show that carbon outgassing from permafrost and uptake of carbon by the land biosphere broadly compensate for each other during the temperature rise of the early last deglaciation.

show abstract

“…However, there are various approaches for how to establish a time series for this parameter; this is a subject of ongoing research. For most simulations in this study we use the most recent time series that has been developed by Hain et al (2014). In Sect.…”

mentioning

confidence: 99%

“…To generate LGM conditions for ∆ 14 C in atmosphere and ocean, we applied the cosmogenic production 14 C rate of shortly before the LGM. This production rate is determined by the strength of the Earth's magnetic field, which shields the atmosphere from high energy cosmic particles, and the solar modulation of the incidence of high energy cosmic particles (Lal and Peters, 1967;Hain et al, 2014). For generating glacial conditions, the average from 25 to 26 kaBP of the Additionally, the equatorward expansion of terrestrial ice sheets is set to 47…”

mentioning

confidence: 99%

A model-data assessment of the role of Southern Ocean processes in the last glacial termination

Eichinger

Shaffer

Albarrán

et al. 2016

Preprint

View full text Add to dashboard Cite

Abstract. The Southern Ocean has been identified as a key player for the global atmospheric temperature and pCO 2 rise across the last glacial termination. One leading hypothesis for explaining the initial pCO 2 step of 38 ppm (Mystery Interval 17.5−14.5 ka) is enhanced upwelling of Southern Ocean deep water that had stayed isolated from surface layers for millennia, thereby accumulating carbon from remineralisation of organic matter. However, the individual influences involved in this interplay of processes are not fully understood. A credible explanation for this remarkable climate change must also be able to

show abstract

Distinct roles of the Southern Ocean and North Atlantic in the deglacial atmospheric radiocarbon decline

Cited by 62 publications

References 88 publications

Simulation of climate, ice sheets and CO<sub>2</sub> evolution during the last four glacial cycles with an Earth system model of intermediate complexity

Simulation of climate, ice sheets and CO<sub>2</sub> evolution during the last four glacial cycles with an Earth system model of intermediate complexity

An improved land biosphere module for use in the DCESS Earth system model (version 1.1) with application to the last glacial termination

A model-data assessment of the role of Southern Ocean processes in the last glacial termination

Contact Info

Product

Resources

About

Distinct roles of the Southern Ocean and North Atlantic in the deglacial atmospheric radiocarbon decline

Cited by 62 publications

References 88 publications

Simulation of climate, ice sheets and CO&lt;sub&gt;2&lt;/sub&gt; evolution during the last four glacial cycles with an Earth system model of intermediate complexity

Simulation of climate, ice sheets and CO&lt;sub&gt;2&lt;/sub&gt; evolution during the last four glacial cycles with an Earth system model of intermediate complexity

An improved land biosphere module for use in the DCESS Earth system model (version 1.1) with application to the last glacial termination

A model-data assessment of the role of Southern Ocean processes in the last glacial termination

Contact Info

Product

Resources

About

Simulation of climate, ice sheets and CO<sub>2</sub> evolution during the last four glacial cycles with an Earth system model of intermediate complexity

Simulation of climate, ice sheets and CO<sub>2</sub> evolution during the last four glacial cycles with an Earth system model of intermediate complexity