Coupled Northern Hemisphere permafrost–ice-sheet evolution over the last glacial cycle

Willeit, Matteo; Ganopolski, Andrey

doi:10.5194/cp-11-1165-2015

Cited by 19 publications

(11 citation statements)

References 41 publications

(94 reference statements)

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“…A future modeling improvement would be to couple VAMPERS with the ice sheet component in iLOVECLIM, as was recently done in the CLIMBER-2 model (Willeit and Ganopolski, 2015). Such a coupling would combine the impacts of varying properties of ice sheet thickness, local ground heat flux and surface climate, and would result in a more realistic simulation of permafrost occurrence and thickness under ice sheets and following deglaciation.…”

Section: Discussionmentioning

confidence: 99%

Coupling of VAMPERS within iLOVECLIM: experiments during the LGM and Last Deglaciation

Kitover

Renssen

Balen

et al. 2019

J Quaternary Science

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The VAMPERS (Vrije Universiteit Amsterdam Permafrost Snow Model) has been coupled within iLOVECLIM, an earth system model. This advancement allows the thermal coupling between permafrost and climate to be examined from a millennial timescale using equilibrium experiments during the Last Glacial Maximum (21 ka) and transient experiments for the subsequent deglaciation period (21–11 ka). It appears that the role of permafrost during both stable and transitional (glacial–interglacial) climate periods is seasonal, resulting in cooler summers and warmer winters by approximately ±2 °C maximum. This conclusion reinforces the importance of including the active layer within climate models. In addition, the coupling of VAMPERS also yields a simulation of transient permafrost conditions, not only for estimating areal changes in extent but also total permafrost gain/loss.

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Section: Discussionmentioning

confidence: 99%

Coupling of VAMPERS within iLOVECLIM: experiments during the LGM and Last Deglaciation

Kitover

Renssen

Balen

et al. 2019

J Quaternary Science

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“…Physical details of the bedrock-ice interface are not of interest here in contrast to more sophisticated bed thermal models (Tarasov and Peltier, 2007;Willeit and Ganopolski, 2015). However, here T 0 is not the temperature of the bedrock and the conductivity of the bedrock does not need to be taken into account.…”

Section: Vertical Diffusion Of Heat and Frictional Heatingmentioning

confidence: 99%

Tracer transport in an isochronal ice-sheet model

Born

2016

J. Glaciol.

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ABSTRACT. The full history of ice sheet and climate interactions is recorded in the vertical profiles of geochemical tracers in polar ice sheets. Numerical simulations of these archives promise great advances both in the interpretation of these reconstructions and the validation of the models themselves. However, fundamental mathematical shortcomings of existing models subject tracers to spurious diffusion, thwarting straightforward solutions. Here, I propose a new vertical discretization for ice-sheet models that eliminates numerical diffusion entirely. Vertical motion through the model mesh is avoided by mimicking the real-world flow of ice as a thinning of underlying layers. A new layer is added to the surface at equidistant time intervals, isochronally, thus identifying each layer uniquely by its time of deposition and age. This new approach is implemented for a two-dimensional section through the summit of the Greenland ice sheet. The ability to directly compare simulations of vertical ice cores with reconstructed data is used to find optimal model parameters from a large ensemble of simulations. It is shown that because this tuning method uses information from all times included in the ice core, it constrains ice-sheet sensitivity more robustly than a realistic reproduction of the modern ice-sheet surface.

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“…With respect to permafrost dynamics, PMIP models have been used to analyse permafrost extent under LGM and PI climate conditions (Saito et al, 2013), but not with respect to changes in permafrost soil carbon storage. Willeit et al (2015) have run the Earth system model CLIMBER-2 over the last glacial cycle to explore the interaction of permafrost and ice-sheet evolution. Using the ORCHIDEE land surface model, Zhu et al (2016) 10 simulated glacial SOC storage in Yedoma deposits showing a rather large potential of these thick ice-and organic-rich sediments to affect the global carbon cycle.…”

Section: Introductionmentioning

confidence: 99%

Deglacial permafrost carbon dynamics in MPI-ESM

Deimling

Kleinen

Hugelius

et al. 2018

Preprint

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We have developed a new module to calculate soil organic carbon (SOC) accumulation in perennially frozen ground in the land surface model JSBACH. Running this offline version of MPI-ESM we have modelled permafrost carbon accumulation 15 and release from the Last Glacial Maximum (LGM) to the Pre-industrial (PI). Our simulated near-surface PI permafrost extent of 16.9 Mio km 2 is close to observational evidence. Glacial boundary conditions, especially ice sheet coverage, result in profoundly different spatial patterns of glacial permafrost extent. Deglacial warming leads to large-scale changes in soil temperatures, manifested in permafrost disappearance in southerly regions, and permafrost aggregation in formerly glaciated grid cells. In contrast to the large spatial shift in simulated permafrost occurrence, we infer an only moderate increase of total 20LGM permafrost area (18.3 Mio km 2 ) -together with pronounced changes in the depth of seasonal thaw. Reconstructions suggest a larger spread of glacial permafrost towards more southerly regions, but with a highly uncertain extent of noncontinuous permafrost.Compared to a control simulation without describing the transport of SOC into perennially frozen ground, the implementation of our newly developed module for simulating permafrost SOC accumulation leads to a doubling of 25 simulated LGM permafrost SOC storage (amounting to a total of ~150 PgC). Despite LGM temperatures favouring a larger permafrost extent, simulated cold glacial temperatures -together with low precipitation and low CO 2 levels -limit vegetation productivity and therefore prevent a larger glacial SOC build-up in our model. Changes in physical and biogeochemical boundary conditions during deglacial warming lead to an increase in mineral SOC storage towards the Holocene (168 PgC at PI), which is below observational estimates (575 PgC in continuous and discontinuous permafrost). 30Additional model experiments clarified the sensitivity of simulated SOC storage to model parameters, affecting long-term soil carbon respiration rates and simulated active layer depths. Rather than a steady increase in carbon release from the LGM to PI as a consequence of deglacial permafrost degradation, our results suggest alternating phases of soil carbon Clim. Past Discuss., https://doi

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Coupled Northern Hemisphere permafrost–ice-sheet evolution over the last glacial cycle

Cited by 19 publications

References 41 publications

Coupling of VAMPERS within iLOVECLIM: experiments during the LGM and Last Deglaciation

Coupling of VAMPERS within iLOVECLIM: experiments during the LGM and Last Deglaciation

Tracer transport in an isochronal ice-sheet model

Deglacial permafrost carbon dynamics in MPI-ESM

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