Glacial abrupt climate changes and Dansgaard‐Oeschger oscillations in a coupled climate model

Wang, Zhaomin; Mysak, Lawrence A.

doi:10.1029/2005pa001238

Cited by 46 publications

(39 citation statements)

References 63 publications

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“…Our data further indicate that (1) the duration and frequency of the millennial-scale events change systematically throughout the course of a glacial period, and (2) that the general nature of these changes is reproducible for the last two glacial periods. These observations suggest a link between ice volume, which could have changed in broadly the same fashion during the last two glacial periods, and the character, duration and pacing of millennial-scale events, consistent with recent simulation results that the mean climate state represented by global ice-volume can pace climatic events 8,9 . Therefore, ice volume, affecting ice dynamics, probably with feedbacks affecting atmospheric and oceanic circulation, may have a significant influence on GIS and CIS events.…”

supporting

confidence: 88%

“…Our understanding of these factors remains incomplete, however, owing to gaps in the record of monsoon history over the past two interglacial-glacial cycles. In particular, missing sections have hampered our ability to test ideas about orbital-scale controls on the monsoon [5][6][7] , the causes of millennial-scale events 8,9 and relationships between changes in the monsoon and climate in other regions. Here we present an absolute-dated oxygen isotope record from Sanbao cave, central China, that completes a Chinesecave-based record of the strength of the East Asian monsoon that covers the past 224,000 years.…”

mentioning

confidence: 99%

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Millennial- and orbital-scale changes in the East Asian monsoon over the past 224,000 years

Wang

Cheng

Edwards

et al. 2008

Nature

1,689

109

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High-resolution speleothem records from China have provided insights into the factors that control the strength of the East Asian monsoon [1][2][3][4] . Our understanding of these factors remains incomplete, however, owing to gaps in the record of monsoon history over the past two interglacial-glacial cycles. In particular, missing sections have hampered our ability to test ideas about orbital-scale controls on the monsoon [5][6][7] , the causes of millennial-scale events 8,9 and relationships between changes in the monsoon and climate in other regions. Here we present an absolute-dated oxygen isotope record from Sanbao cave, central China, that completes a Chinesecave-based record of the strength of the East Asian monsoon that covers the past 224,000 years. The record is dominated by 23,000-year-long cycles that are synchronous within dating errors with summer insolation at 656 N (ref. 10), supporting the idea that tropical/subtropical monsoons respond dominantly and directly to changes in Northern Hemisphere summer insolation on orbital timescales 5 . The cycles are punctuated by millennial-scale strongsummer-monsoon events (Chinese interstadials 1 ), and the new record allows us to identify the complete series of these events over the past two interglacial-glacial cycles. Their duration decreases and their frequency increases during glacial build-up in both the last and penultimate glacial periods, indicating that ice sheet size affects their character and pacing. The ages of the events are exceptionally well constrained and may thus serve as benchmarks for correlating and calibrating climate records.The last glacial period is characterized by millennial-scale events, first identified in Greenland, including 25 Greenland interstadials (GIS) during the last interglacial-glacial period [11][12][13] . We previously identified a number of Chinese interstadial (CIS) events 2,4 (relatively strong summer millennial-scale East Asian monsoon, EAM, events) and correlated them with analogous GIS events. We also identified CIS events from portions of the penultimate glacial period, and established a nomenclature with last glacial period CIS denoted CIS A1, A2, and so on, from youngest to oldest, and those of the penultimate glacial period denoted CIS B1, B2, and so on 1 . Here we present an EAM record from Sanbao cave, together with our previous Hulu records 1,2 , and characterize the complete CIS series for the last and penultimate interglacial-glacial cycles, including events not previously identified.Sanbao cave is in Hubei province, central China, on the northern slope of Mt Shennongjia, near the southern edge of the Chinese loess plateau (110u 269 E, 31u 409 N, 1,900 m above sea level). Regional climate is dominated by the EAM, a sub-system of the Asian monsoon (AM) (Supplementary Fig. 1), with a mean annual rainfall of 1,900-2,000 mm and a mean temperature of 8-9 uC. During boreal summer (June to September), warm/humid air from the equatorial Pacific penetrates to the northern slope of Mt Shennongjia, delivering mo...

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supporting

confidence: 88%

mentioning

confidence: 99%

Millennial- and orbital-scale changes in the East Asian monsoon over the past 224,000 years

Wang

Cheng

Edwards

et al. 2008

Nature

1,689

109

1,268

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“…Wang and Mysak (2006) found self-sustaining DO-like oscillations and argued that brine rejection (and its effects on upper-ocean buoyancy) was an essential part of the mechanism. Loving and Vallis (2005) found weaker MOC in colder climates with more extensive sea ice cover (with deepwater formation shifted equatorward with the ice edge), arguing that the ice-induced insulation of the sea surface is a necessary condition for weakening the MOC.…”

Section: Discussionmentioning

confidence: 99%

The Role of Oceans and Sea Ice in Abrupt Transitions between Multiple Climate States

2013

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The coupled climate dynamics underlying large, rapid, and potentially irreversible changes in ice cover are studied. A global atmosphere-ocean-sea ice general circulation model with idealized aquaplanet geometry is forced by gradual multi-millennial variations in solar luminosity. The model traverses a hysteresis loop between warm ice-free conditions and cold glacial conditions in response to 65 W m 22 variations in global,annual-mean insolation. Comparison of several model configurations confirms the importance of polar ocean processes in setting the sensitivity and time scales of the transitions. A ''sawtooth'' character is found with faster warming and slower cooling, reflecting the opposing effects of surface heating and cooling on upper-ocean buoyancy and, thus, effective heat capacity. The transition from a glacial to warm, equable climate occurs in about 200 years. In contrast to the ''freshwater hosing'' scenario, transitions are driven by radiative forcing and sea ice feedbacks. The ocean circulation, and notably the meridional overturning circulation (MOC), does not drive the climate change. The MOC (and associated heat transport) collapses poleward of the advancing ice edge, but this is a purely passive response to cooling and ice expansion. The MOC does, however, play a key role in setting the time scales of the transition and contributes to the asymmetry between warming and cooling.

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“…Note that these influences may also be enhanced through feedbacks. In particular, sea ice extent variations are often given as trigger (Wang and Mysak, 2006) or amplifiers (Li et al, 2005) of abrupt warming events.…”

Section: Millennial To Sub-millennial Scale Gis Variabilitymentioning

confidence: 99%

“…Numerous studies have already shown that millennial scale climatic variability was reduced during MIS 2 and MIS 4 in relation with ice sheet volume (e.g. McManus et al, 1999;Schulz et al, 2002;Wang and Mysak, 2006;NorthGRIP c.m., 2004;Margari et al, 2010). Our study suggests that the bipolar seesaw was also affected during these cold periods.…”

Section: Millennial Scale Variationsmentioning

confidence: 99%

Millennial and sub-millennial scale climatic variations recorded in polar ice cores over the last glacial period

et al. 2010

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Abstract. Since its discovery in Greenland ice cores, the millennial scale climatic variability of the last glacial period has been increasingly documented at all latitudes with studies focusing mainly on Marine Isotopic Stage 3 (MIS 3; 28-60 thousand of years before present, hereafter ka) and characterized by short Dansgaard-Oeschger (DO) events. Recent and new results obtained on the EPICA and NorthGRIP ice cores now precisely describe the rapid variations of Antarctic and Greenland temperature during MIS 5 (73.5-123 ka), a time period corresponding to relatively high sea level. The results display a succession of abrupt events associated with long Greenland InterStadial phases (GIS) enabling us to highlight a sub-millennial scale climatic variability depicted by (i) short-lived and abrupt warming events preceding some GIS (precursor-type events) and (ii) abrupt warming events at the end of some GIS (rebound-type events). The occurrence of these sub-millennial scale events is suggested to be driven by the insolation at high northern latitudes together with the internal forcing of ice sheets. Thanks to a recent NorthGRIP-EPICA Dronning Maud Land (EDML) common timescale over MIS 5, the bipolar sequence of climatic events can be established at millennial to sub-millennial timescale. This shows that for extraordinary long stadial durations the accompanying Antarctic warming amplitude cannot be described by a simple linear relationship between the two as Correspondence to: E. Capron (emilie.capron@lsce.ipsl.fr) expected from the bipolar seesaw concept. We also show that when ice sheets are extensive, Antarctica does not necessarily warm during the whole GS as the thermal bipolar seesaw model would predict, questioning the Greenland ice core temperature records as a proxy for AMOC changes throughout the glacial period.

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Glacial abrupt climate changes and Dansgaard‐Oeschger oscillations in a coupled climate model

Cited by 46 publications

References 63 publications

Millennial- and orbital-scale changes in the East Asian monsoon over the past 224,000 years

Millennial- and orbital-scale changes in the East Asian monsoon over the past 224,000 years

The Role of Oceans and Sea Ice in Abrupt Transitions between Multiple Climate States

Millennial and sub-millennial scale climatic variations recorded in polar ice cores over the last glacial period

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