Impact of ice sheet meltwater fluxes on the climate evolution at the onset of the Last Interglacial

Abstract. Large climate perturbations occurred during Termination II when the ice sheets retreated from their glacial configuration. Here we investigate the impact of ice sheet changes and associated freshwater fluxes on the climate evolution at the onset of the Last Interglacial. The period from 135 to 120 kyr BP is simulated with the Earth system model of intermediate complexity LOVECLIM v.1.3 with prescribed evolution of the Antarctic ice sheet, the Greenland ice sheet and the other Northern Hemisphere ice sheets. Variations in meltwater fluxes from the Northern Hemisphere ice sheets lead to North Atlantic temperature changes and modifications of the strength of the Atlantic meridional overturning circulation. By means of the interhemispheric see-saw effect, variations in the Atlantic meridional overturning circulation also give rise to temperature changes in the Southern Hemisphere, which are modulated by the direct impact of Antarctic meltwater fluxes into the Southern Ocean. Freshwater fluxes from the melting Antarctic ice sheet lead to a millennial time scale oceanic cold event in the Southern Ocean with expanded sea ice as evidenced in some ocean sediment cores, which may be used to constrain the timing of ice sheet retreat.

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Impact of ice sheet meltwater fluxes on the climate evolution at the onset of the Last Interglacial

Climate of the Past ◽

10.5194/cp-12-1721-2016 ◽

2016 ◽

Vol 12 (8) ◽

pp. 1721-1737 ◽

Cited By ~ 10

Author(s):

Heiko Goelzer ◽

Philippe Huybrechts ◽

Marie-France Loutre ◽

Thierry Fichefet

Keyword(s):

Southern Ocean ◽

Ice Sheets ◽

Ice Sheet ◽

Atlantic Meridional Overturning Circulation ◽

Meridional Overturning Circulation ◽

Last Interglacial ◽

Temperature Changes ◽

Freshwater Fluxes ◽

Climate Evolution ◽

Meridional Overturning

Abstract. Large climate perturbations occurred during the transition between the penultimate glacial period and the Last Interglacial (Termination II), when the ice sheets retreated from their glacial configuration. Here we investigate the impact of ice sheet changes and associated freshwater fluxes on the climate evolution at the onset of the Last Interglacial. The period from 135 to 120 kyr BP is simulated with the Earth system model of intermediate complexity LOVECLIM v.1.3 with prescribed evolution of the Antarctic ice sheet, the Greenland ice sheet, and the other Northern Hemisphere ice sheets. Variations in meltwater fluxes from the Northern Hemisphere ice sheets lead to North Atlantic temperature changes and modifications of the strength of the Atlantic meridional overturning circulation. By means of the interhemispheric see-saw effect, variations in the Atlantic meridional overturning circulation also give rise to temperature changes in the Southern Hemisphere, which are additionally modulated by the direct impact of Antarctic meltwater fluxes into the Southern Ocean. Freshwater fluxes from the melting Antarctic ice sheet lead to a millennial timescale oceanic cold event in the Southern Ocean with expanded sea ice as evidenced in some ocean sediment cores, which may be used to constrain the timing of ice sheet retreat.

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Inception of the Northern European ice sheet due to contrasting ocean and insolation forcing

Quaternary Research ◽

10.1016/j.yqres.2006.07.007 ◽

2007 ◽

Vol 67 (1) ◽

pp. 128-135 ◽

Cited By ~ 28

Author(s):

Bjørg Risebrobakken ◽

Trond Dokken ◽

Odd Helge Otterå ◽

Eystein Jansen ◽

Yongqi Gao ◽

...

Keyword(s):

Northern Hemisphere ◽

Ice Sheet ◽

Atlantic Meridional Overturning Circulation ◽

Meridional Overturning Circulation ◽

Last Interglacial ◽

Northern Limb ◽

Northern European ◽

Meridional Overturning ◽

Insolation Forcing ◽

The Last Glacial

AbstractAbout 115,000 yr ago the last interglacial reached its terminus and nucleation of new ice-sheet growth was initiated. Evidence from the northernmost Nordic Seas indicate that the inception of the last glacial was related to an intensification of the Atlantic Meridional Overturning Circulation (AMOC) in its northern limb. The enhanced AMOC, combined with minimum Northern hemisphere insolation, introduced a strong sea–land thermal gradient that, together with a strong wintertime latitudinal insolation gradient, increased the storminess and moisture transport to the high Northern European latitudes at a time when the Northern hemisphere summer insolation approached its minimum.

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Modeling the influence of Greenland ice sheet melting on the Atlantic meridional overturning circulation during the next millennia

Geophysical Research Letters ◽

10.1029/2007gl029516 ◽

2007 ◽

Vol 34 (10) ◽

Cited By ~ 94

Author(s):

E. Driesschaert ◽

T. Fichefet ◽

H. Goosse ◽

P. Huybrechts ◽

I. Janssens ◽

...

Keyword(s):

Ice Sheet ◽

Greenland Ice Sheet ◽

Atlantic Meridional Overturning Circulation ◽

Meridional Overturning Circulation ◽

Overturning Circulation ◽

Meridional Overturning

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High resolution evidence for linkages between NW European ice sheet instability and Atlantic Meridional Overturning Circulation

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2005.12.023 ◽

2006 ◽

Vol 243 (3-4) ◽

pp. 476-488 ◽

Cited By ~ 94

Author(s):

V.L. Peck ◽

I.R. Hall ◽

R. Zahn ◽

H. Elderfield ◽

F. Grousset ◽

...

Keyword(s):

High Resolution ◽

Ice Sheet ◽

Atlantic Meridional Overturning Circulation ◽

Meridional Overturning Circulation ◽

Overturning Circulation ◽

Meridional Overturning

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Hindcasting the continuum of Dansgaard–Oeschger variability: mechanisms, patterns and timing

Climate of the Past Discussions ◽

10.5194/cpd-9-4771-2013 ◽

2013 ◽

Vol 9 (4) ◽

pp. 4771-4806 ◽

Cited By ~ 1

Author(s):

L. Menviel ◽

A. Timmermann ◽

T. Friedrich ◽

M. H. England

Keyword(s):

North Atlantic ◽

Global Climate ◽

Ice Sheet ◽

Meridional Overturning Circulation ◽

External Boundary ◽

3 Dimensional ◽

Ice Volume ◽

Freshwater Fluxes ◽

Meridional Overturning ◽

The Continuum

Abstract. Millennial-scale variability associated with Dansgaard–Oeschger (DO) and Heinrich events (HE) is arguably one of the most puzzling climate phenomena ever discovered in paleoclimate archives. Here, we set out to elucidate the underlying dynamics by conducting a transient global hindcast simulation with a 3-dimensional intermediate complexity Earth system model covering the period 50 ka BP to 30 ka BP. The model is forced by time-varying external boundary conditions (greenhouse gases, orbital forcing, and ice sheet orography and albedo) and anomalous North Atlantic freshwater fluxes, which mimic the effects of changing Northern Hemisphere ice-volume on millennial timescales. Together these forcings generate a realistic global climate trajectory, as demonstrated by an extensive model/paleo data comparison. Our analysis is consistent with the idea that variations in ice sheet calving and related changes of the Atlantic Meridional Overturning Circulation were the main drivers for the continuum of DO and HE variability seen in paleorecords across the globe.

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The Atlantic Meridional Overturning Circulation (AMOC) simulated during interglacials and its impact on climate

10.5194/egusphere-egu21-3432 ◽

2021 ◽

Author(s):

Zhiyi Jiang ◽

Chris Brierley ◽

David Thornalley ◽

Sophie Sax

Keyword(s):

Spatial Structure ◽

Surface Temperature ◽

Global Climate ◽

Atlantic Meridional Overturning Circulation ◽

Meridional Overturning Circulation ◽

Last Interglacial ◽

Overturning Circulation ◽

Poleward Heat Transport ◽

Meridional Overturning ◽

Proxy Reconstructions

The Atlantic Meridional Overturning Circulation (AMOC) is a key mechanism of poleward heat transport and an important part of the global climate system. How it responded to past changes inforcing, such as experienced during Quaternary interglacials, is an intriguing and open question. Previous modelling studies suggest an enhanced AMOC in the mid-Holocene compared to the pre-industrial period. In previous simulations from the Palaeoclimate Modelling Intercomparison Project (PMIP), this arose from feedbacks between sea ice and AMOC changes, which also depended on resolution. Here I present aninitial analysis of the recently available PMIP4 simulations. This shows the overall strength of the AMOC does not markedly change between the mid-Holocene and piControl experiments (at least looking at the maximum of the mean meridional mass overturning streamfunction below 500m at 30oN and 50oN). This is not inconsistent with the proxy reconstructions using sortable silt and Pa/Th for the mid-Holocene. Here we analyse changes in the spatial structure of the meridional overturning circulation, along with their fingerprints on the surface temperature (computed through regression). We then estimate the percentage of the simulated surface temperature changes between the mid-Holocene and pre-industrial period that can be explained by AMOC. Furthermore, the analysis for the changes in the AMOC spatial structure has been extended to see if the same patterns of change hold for the last interglacial. The simulations will be compared to existing proxy reconstructions, as well as new palaeoceanographic reconstructions.

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Different ice sheets – different AMOC? Revisiting the ice-sheet effect on the LGM AMOC

10.5194/egusphere-egu21-8652 ◽

2021 ◽

Author(s):

Marlene Klockmann ◽

Marie-Luise Kapsch ◽

Uwe Mikolajewicz

Keyword(s):

Southern Ocean ◽

Climate Models ◽

Ice Sheets ◽

Ice Sheet ◽

Meridional Overturning Circulation ◽

Salt Transport ◽

Max Planck ◽

Good Opportunity ◽

Transient Simulations ◽

Opposing Effects

Coupled climate models have produced very different states of the Atlantic Meridional Overturning Circulation (AMOC) in simulations of the Last Glacial Maximum (LGM). In particular, many of them failed to capture the shoaling of the upper AMOC cell, which was indicated by reconstructions. In sensitivity simulations with the Max-Planck-Institute Earth System Model (MPI-ESM) we found that the glacial AMOC response is the sum of two large opposing effects: a strengthening and deepening of the upper cell in response to the glacial ice sheets and a weakening and shoaling of the upper cell in response to the low glacial greenhouse gas concentrations. The magnitude of the respective effects likely depends on the background climate, the ice sheet reconstruction used, and model specifics such as the representation of brine release in the Southern Ocean. Transient simulations of the deglaciation with two differently tuned versions of MPI-ESM and two different ice-sheet reconstructions differ strongly in their respective AMOC states during the LGM. These simulations, together with selected PMIP3 and PMIP4 LGM simulations, provide a good opportunity to compare the effect of different ice sheet reconstructions on the glacial AMOC. We compare key variables such as water mass properties, salt transport and Southern Ocean sea-ice formation across this ensemble of opportunity with the aim of increasing our understanding of the role of ice sheets in the glacial AMOC response.

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