“Sticky” Ice Sheets May Have Led to More Intense Glacial Cycles

Variations in Earth’s orbit pace the glacial-interglacial cycles of the Quaternary, but the mechanisms that transform regional and seasonal variations in solar insolation into glacial-interglacial cycles are still elusive. Here, we present transient simulations of coevolution of climate, ice sheets, and carbon cycle over the past 3 million years. We show that a gradual lowering of atmospheric CO2and regolith removal are essential to reproduce the evolution of climate variability over the Quaternary. The long-term CO2decrease leads to the initiation of Northern Hemisphere glaciation and an increase in the amplitude of glacial-interglacial variations, while the combined effect of CO2decline and regolith removal controls the timing of the transition from a 41,000- to 100,000-year world. Our results suggest that the current CO2concentration is unprecedented over the past 3 million years and that global temperature never exceeded the preindustrial value by more than 2°C during the Quaternary.

Download Full-text

Dynamics of ~100-kyr glacial cycles during the early Miocene

Climate of the Past Discussions ◽

10.5194/cpd-6-2741-2010 ◽

2010 ◽

Vol 6 (6) ◽

pp. 2741-2766

Author(s):

D. Liebrand ◽

L. J. Lourens ◽

D. A. Hodell ◽

B. de Boer ◽

R. S. W. van de Wal

Keyword(s):

Northern Hemisphere ◽

Ice Sheets ◽

Ice Sheet ◽

Early Miocene ◽

Glacial Cycles ◽

Threshold Response ◽

Ice Cap ◽

Eastern Atlantic Ocean ◽

Oxygen Isotope Record ◽

Isotope Record

Abstract. Here, we present high-resolution stable isotope records from ODP Site 1264 in the South-Eastern Atlantic Ocean, which resolve the latest Oligocene to early Miocene (23.7–18.9 Ma) climate changes. Using an inverse modelling technique, we decomposed the oxygen isotope record into temperature and ice volume and found that the Antarctic ice sheet expanded during distinct episodes (e.g., Mi zones) of low short-term (~100-kyr) eccentricity forcing, which occur two to four long-term (400-kyr) eccentricity cycles apart. We argue that a~non-linear mechanism, such as the merging of (several) large East Antarctic ice sheets, caused the build-up of a larger ice sheet. During the termination phases of these larger ice sheets, on the contrary, we find a more linear response of ice-sheet variability to orbital forcing and climate became highly sensitive to the ~100-kyr eccentricity cycle. At the Oligocene-Miocene transition the model output indicates a decrease in Northern Hemisphere temperatures such that a small ice cap could develop on Greenland. This Supports the hypothesis of a threshold response for the development of Northern Hemisphere land ice to decreasing pCO2.

Download Full-text

Investigating the evolution of major Northern Hemisphere ice sheets during the last glacial-interglacial cycle

Climate of the Past ◽

10.5194/cp-5-329-2009 ◽

2009 ◽

Vol 5 (3) ◽

pp. 329-345 ◽

Cited By ~ 62

Author(s):

S. Bonelli ◽

S. Charbit ◽

M. Kageyama ◽

M.-N. Woillez ◽

G. Ramstein ◽

...

Keyword(s):

Northern Hemisphere ◽

Climate Model ◽

Ice Sheets ◽

Ice Sheet ◽

Co2 Concentration ◽

Atmospheric Co2 ◽

Glacial Cycle ◽

Last Glacial ◽

Atmospheric Co2 Concentration ◽

The Last Glacial

Abstract. A 2.5-dimensional climate model of intermediate complexity, CLIMBER-2, fully coupled with the GREMLINS 3-D thermo-mechanical ice sheet model is used to simulate the evolution of major Northern Hemisphere ice sheets during the last glacial-interglacial cycle and to investigate the ice sheets responses to both insolation and atmospheric CO2 concentration. This model reproduces the main phases of advance and retreat of Northern Hemisphere ice sheets during the last glacial cycle, although the amplitude of these variations is less pronounced than those based on sea level reconstructions. At the last glacial maximum, the simulated ice volume is 52.5×1015 m3 and the spatial distribution of both the American and Eurasian ice complexes is in reasonable agreement with observations, with the exception of the marine parts of these former ice sheets. A set of sensitivity studies has also been performed to assess the sensitivity of the Northern Hemisphere ice sheets to both insolation and atmospheric CO2. Our results suggest that the decrease of summer insolation is the main factor responsible for the early build up of the North American ice sheet around 120 kyr BP, in agreement with benthic foraminifera δ18O signals. In contrast, low insolation and low atmospheric CO2 concentration are both necessary to trigger a long-lasting glaciation over Eurasia.

Download Full-text

Potential impact of the northern hemisphere Quaternary ice sheets on the frequencies of the astroclimatic orbital parameters

Journal of Geophysical Research Atmospheres ◽

10.1029/jd095id06p07573 ◽

1990 ◽

Vol 95 (D6) ◽

pp. 7573 ◽

Cited By ~ 11

Author(s):

Véronique Dehant ◽

Marie-France Loutre ◽

André Berger

Keyword(s):

Northern Hemisphere ◽

Ice Sheets ◽

Orbital Parameters ◽

Potential Impact

Download Full-text

Investigating the mechanisms leading to the deglaciation of past continental northern hemisphere ice sheets with the CLIMBER–GREMLINS coupled model

Global and Planetary Change ◽

10.1016/j.gloplacha.2005.01.002 ◽

2005 ◽

Vol 48 (4) ◽

pp. 253-273 ◽

Cited By ~ 27

Author(s):

Sylvie Charbit ◽

Masa Kageyama ◽

Didier Roche ◽

Catherine Ritz ◽

Gilles Ramstein

Keyword(s):

Northern Hemisphere ◽

Ice Sheets ◽

Coupled Model

Download Full-text

Influence of ablation-related processes in the built-up of simulated Northern Hemisphere ice sheets during the last glacial cycle

The Cryosphere Discussions ◽

10.5194/tcd-6-4897-2012 ◽

2012 ◽

Vol 6 (6) ◽

pp. 4897-4938 ◽

Cited By ~ 1

Author(s):

S. Charbit ◽

C. Dumas ◽

M. Kageyama ◽

D. M. Roche ◽

C. Ritz

Keyword(s):

Northern Hemisphere ◽

Ice Sheets ◽

Ice Sheet ◽

Glacial Cycle ◽

Satisfactory Description ◽

Last Glacial ◽

Transient Simulations ◽

Main Driver ◽

The Impact ◽

The Last Glacial

Abstract. Since the original formulation of the positive-degree-day (PDD) method, different PDD calibrations have been proposed in the literature in response to the increasing number of observations. Although these formulations provide a satisfactory description of the present-day Greenland geometry, they have not all been tested for paleo ice sheets. Using the climate-ice sheet model CLIMBER-GRISLI coupled with different PDD models, we evaluate how the parameterization of the ablation may affect the evolution of Northern Hemisphere ice sheets in the transient simulations of the last glacial cycle. Results from fully coupled simulations are compared to time-slice experiments carried out at different key periods of the last glacial period. We find large differences in the simulated ice sheets according to the chosen PDD model. These differences occur as soon as the onset of glaciation, therefore affecting the subsequent evolution of the ice system. To further investigate how the PDD method controls this evolution, special attention is given to the role of each PDD parameter. We show that glacial inception is critically dependent on the representation of the impact of the temperature variability from the daily to the inter-annual time scale, whose effect is modulated by the refreezing scheme. Finally, an additional set of sensitivity experiments has been carried out to assess the relative importance of melt processes with respect to initial ice sheet configuration in the construction and the evolution of past Northern Hemisphere ice sheets. Our analysis reveals that the impacts of the initial ice sheet condition may range from quite negligible to explaining about half of the LGM ice volume depending on the representation of stochastic temperature variations which remain the main driver of the evolution of the ice system.

Download Full-text

Mode transitions in Northern Hemisphere Glaciation: Co-evolution of millennial and orbital variability in Quaternary climate

10.5194/cp-2016-30 ◽

2016 ◽

Cited By ~ 1

Author(s):

David A. Hodell ◽

James E.T. Channell

Keyword(s):

Climate Variability ◽

Northern Hemisphere ◽

North Atlantic ◽

Ice Sheets ◽

Deep Ocean ◽

Progressive Increase ◽

The North ◽

Quaternary Climate ◽

Mode Transitions ◽

Millennial Scale

Abstract. We present a 3.2-Myr record of stable isotopes and physical properties at IODP Site U1308 (re-occupation of DSDP Site 609) located within the ice-rafted detritus (IRD) belt of the North Atlantic. We compare the isotope and lithological proxies at Site U1308 with other North Atlantic records (e.g., Sites 982, 607/U1313 and U1304) to reconstruct the history of orbital and millennial-scale climate variability during the Quaternary. The Site U1308 record documents a progressive increase in the intensity of Northern Hemisphere glacial-interglacial cycles during the late Pliocene and Quaternary with mode transitions at ~ 2.7, 1.5, 0.9 and 0.65 Ma. These transitions mark times of change in the growth and stability of Northern Hemisphere ice sheets. They also coincide with increases in vertical carbon isotope gradients between the intermediate and deep ocean, suggesting changes in deep carbon storage and atmospheric CO2. Orbital and millennial climate variability co-evolved during the Quaternary such that the trend towards larger ice sheets was accompanied by changes in the style, frequency and intensity of millennial-scale variability. This co-evolution may be important for explaining the observed patterns of Quaternary climate change.

Download Full-text

The sensitivity of Northern Hemisphere ice sheets to atmospheric forcing during the last glacial cycle using PMIP3 models

Journal of Glaciology ◽

10.1017/jog.2019.42 ◽

2019 ◽

Vol 65 (252) ◽

pp. 645-661 ◽

Cited By ~ 1

Author(s):

LU NIU ◽

GERRIT LOHMANN ◽

SEBASTIAN HINCK ◽

EVAN J. GOWAN ◽

UTA KREBS-KANZOW

Keyword(s):

Northern Hemisphere ◽

Ice Sheets ◽

Ice Sheet ◽

Climate Forcing ◽

Phase Iii ◽

Temperature Pattern ◽

Glacial Cycle ◽

Large Variability ◽

Last Glacial ◽

The Last Glacial

ABSTRACTThe evolution of Northern Hemisphere ice sheets through the last glacial cycle is simulated with the glacial index method by using the climate forcing from one General Circulation Model, COSMOS. By comparing the simulated results to geological reconstructions, we first show that the modelled climate is capable of capturing the main features of the ice-sheet evolution. However, large deviations exist, likely due to the absence of nonlinear interactions between ice sheet and other climate components. The model uncertainties of the climate forcing are examined using the output from nine climate models from the Paleoclimate Modelling Intercomparison Project Phase III. The results show a large variability in simulated ice sheets between the different models. We find that the ice-sheet extent pattern resembles summer surface air temperature pattern at the Last Glacial Maximum, confirming the dominant role of surface ablation process for high-latitude Northern Hemisphere ice sheets. This study shows the importance of the upper boundary condition for ice-sheet modelling, and implies that careful constraints on climate output is essential for simulating realistic glacial Northern Hemisphere ice sheets.

Download Full-text

Late Pliocene variation in northern hemisphere ice sheets and North Atlantic deep water circulation

Paleoceanography ◽

10.1029/pa004i004p00413 ◽

1989 ◽

Vol 4 (4) ◽

pp. 413-446 ◽

Cited By ~ 401

Author(s):

M. E. Raymo ◽

W. F. Ruddiman ◽

J. Backman ◽

B. M. Clement ◽

D. G. Martinson

Keyword(s):

Northern Hemisphere ◽

North Atlantic ◽

Deep Water ◽

Ice Sheets ◽

North Atlantic Deep Water ◽

Water Circulation ◽

Late Pliocene

Download Full-text

Interglacial climates: Advances in our understanding of warm climate episodes

Progress in Physical Geography Earth and Environment ◽

10.1177/0309133310386869 ◽

2010 ◽

Vol 34 (6) ◽

pp. 845-856 ◽

Cited By ~ 8

Author(s):

Danielle Schreve ◽

Ian Candy

Keyword(s):

Western Europe ◽

Ice Sheets ◽

Ice Cores ◽

Temperate Climate ◽

Warm Climate ◽

Climatic Evolution ◽

Extreme Cold ◽

New Research ◽

Continental Ice Sheets ◽

Shed Light

The Quaternary is characterized by the alternation of relatively brief periods of temperate climate (interglacials) with episodes of extreme cold, often with the build-up of extensive continental ice sheets. Over the last decade, new research has revealed far greater complexity and diversity in the interglacial record than previously recognized, with temperate-climate episodes of markedly different duration, stability and intensity. These findings not only shed light on the climatic parameters behind changing floras and faunas during the Pleistocene but also aid our understanding of climatic evolution during the Holocene (the current interglacial), in particular the search for the most appropriate past analogues. In this progress report, we review the basis for interglacial complexity, drawing upon the evidence from long continuous terrestrial records in the Mediterranean, Antarctic ice cores and river terrace sequences in western Europe, before using the details of the British Quaternary interglacial record as an example of how marine and terrestrial records can be linked.

Download Full-text