Influence of the North Atlantic subpolar gyre circulation on the 4.2 ka BP event

Jalali, Bassem; Sicre, Marie‐Alexandrine; Azuara, Julien; Pellichero, Violaine; Nebout, Nathalie Combourieu

doi:10.5194/cp-15-701-2019

Cited by 14 publications

(14 citation statements)

References 61 publications

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“…Nevertheless, these Mg/Ca SST reconstructions show differences from the previous published SST reconstructions based on alkenone measurements that need further discussion ( Fig. 3f; Cacho et al, 2001;Martrat et al, 2004Martrat et al, , 2014Jiménez-Amat and Zahn, 2015).…”

contrasting

confidence: 67%

“…With this goal, here we present a new highresolution Holocene SST record based on the Mg/Ca ratio in the planktonic foraminifera G. bulloides from core ALB-2 of the Alboran Sea. This record is also compared with three other Mg/Ca ratios for G. bulloides derived SST records from the western Mediterranean, two new ones (MD95-2043 and MD99-2343), and another that was previously published (ODP 976;Jiménez-Amat and Zahn, 2015). The western Mediterranean Sea has been intensively studied and several SST records exist, mostly based on the application of the UK'37 index measured on alkenones (Cacho et al, 2001;Martrat et al, 2004;Rodrigo-Gámiz et al, 2014;Ausin et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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Holocene hydrography evolution in the Alboran Sea: a multi-record and multi-proxy comparison

et al. 2019

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Abstract. A new high-resolution deglacial and Holocene sea surface temperature (SST) reconstruction is presented for the Alboran Sea (western Mediterranean), based on Mg∕Ca ratios measured in the planktonic foraminifera Globigerina bulloides. This new record is evaluated by comparison with other Mg∕Ca SST records and previously published alkenone SST reconstructions from the same region for both the Holocene and glacial periods. In all cases there is a high degree of coherence between the different Mg∕Ca SST records but strong discrepancies when compared to the alkenone SST records. We argue that these discrepancies are due to differences in the proxy response during deglaciation which we hypothesize to reflect a resilience strategy of G. bulloides, changing its main growth season, and consequently Mg∕Ca records a shorter deglacial warming than alkenones. In contrast, short-term Holocene SST variability is larger in the Mg∕Ca SST than in the alkenone SST records. We propose that the larger Mg∕Ca SST variability is a result of spring temperatures variability, while the smoothed alkenone SST variability represents averaged annual temperatures. The Mg∕Ca SST record differentiates the Holocene into three periods: (1) the warmest SST values occurred during the Early Holocene (11.7–9 cal. kyr BP), (2) a continuous cooling trend occurred during the Middle Holocene that culminated in the coldest Holocene SST having a double cold peak structure centred at around 4.2 cal. kyr BP, and (3) the Late Holocene (4.2 cal. kyr BP to present) did not follow any clear cooling/warming trend although millennial-scale oscillations were enhanced. This SST evolution is discussed in the context of the changing properties in the Atlantic inflow water associated with North Atlantic circulation conditions and also with local hydrographical and atmospheric changes. We propose that a tight link between North Atlantic circulation patterns and the inflow of surface waters into the Mediterranean played a major role in controlling Holocene climatic variability of this region.

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confidence: 67%

Section: Introductionmentioning

confidence: 99%

Holocene hydrography evolution in the Alboran Sea: a multi-record and multi-proxy comparison

et al. 2019

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“…Consequently, the uncertainties associated with these complementary SST records are larger than those associated with the ALB-2 sediment core, which is the main focus of this study. G. bulloides Mg/Ca ratios from core ODP 976, also included in the discussion, have already been published by Jiménez-Amat and Zahn (2015).…”

Section: Chronologiesmentioning

confidence: 99%

“…We now compare the new δ 18 O record from ALB-2 to other previously published high-resolution δ 18 O records from the western Mediterranean (Cacho et al, 1999;Frigola et al, 2007;Jiménez-Amat and Zahn, 2015) in order to evaluate the regional significance of the recorded signal (Fig. 2).…”

Section: Holocene Evolution In Western Mediterranean G Bulloides -δ 18 O Recordsmentioning

confidence: 99%

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Catalá¹

2019

Preprint

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A new high-resolution deglacial and Holocene sea surface temperature (SST) reconstruction is presented for the Alboran Sea (western Mediterranean), based on Mg/Ca ratios measured in the planktonic foraminifera Globigerina bulloides. This new record is evaluated by comparison with other Mg/Ca SST records and previously published alkenone SST reconstructions from the same region for both the Holocene and glacial periods. In all cases there is a high degree of coherence between the different Mg/Ca SST records but strong discrepancies when compared to the alkenone SST records. We argue that these discrepancies are due to differences in the proxy response during deglaciation which we hypothesize to reflect a resilience strategy of G. bulloides, changing its main growth season, and consequently Mg/Ca records a shorter deglacial warming than alkenones. In contrast, short-term Holocene SST variability is larger in the Mg/Ca SST than in the alkenone SST records. We propose that the larger Mg/Ca SST variability is a result of spring temperatures variability, while the smoothed alkenone SST variability represents averaged annual temperatures. The Mg/Ca SST record differentiates the Holocene into three periods: (1) the warmest SST values occurred during the Early Holocene (11.7-9 cal. kyr BP), (2) a continuous cooling trend occurred during the Middle Holocene that culminated in the coldest Holocene SST having a double cold peak structure centred at around 4.2 cal. kyr BP, and (3) the Late Holocene (4.2 cal. kyr BP to present) did not follow any clear cooling/warming trend although millennial-scale oscillations were enhanced. This SST evolution is discussed in the context of the changing properties in the Atlantic inflow water associated with North Atlantic circulation conditions and also with local hydrographical and atmospheric changes. We propose that a tight link between North Atlantic circulation patterns and the inflow of surface waters into the Mediterranean played a major role in controlling Holocene climatic variability of this region.

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“…Such a first evidence of climate related collapses or transformations in ancient societies have promoted intense investigations of the "climatic" 4.2 ka BP event, which resulted in a variety of associated paleoclimatic studies from the Mediterranean area [6,7,11,12], Asia [13][14][15], North America [16], the northern North Atlantic region [17][18][19], and the southern hemisphere as well [20,21]. Altogether, paleoclimatic studies point to a series of climatic anomalies between 4400 and 3800 cal.…”

Section: Introductionmentioning

confidence: 99%

Fossil leaf wax hydrogen isotopes reveal variability of Atlantic and Mediterranean climate forcing on the southeast Iberian Peninsula between 6000 to 3000 cal. BP

et al. 2020

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Many recently published papers have investigated the spatial and temporal manifestation of the 4.2 ka BP climate event at regional and global scales. However, questions with regard to the potential drivers of the associated climate change remain open. Here, we investigate the interaction between Atlantic and Mediterranean climate forcing on the south-eastern Iberian Peninsula during the mid- to late Holocene using compound-specific hydrogen isotopes from fossil leaf waxes preserved in marine sediments. Variability of hydrogen isotope values in the study area is primarily related to changes in the precipitation source and indicates three phases of increased Mediterranean sourced precipitation from 5450 to 5350 cal. BP, from 5150 to 4300 cal. BP including a short-term interruption around 4800 cal. BP, and from 3400 to 3000 cal. BP interrupted around 3200 cal. BP. These phases are in good agreement with times of prevailing positive modes of the North Atlantic Oscillation (NAO) and reduced storm activity in the Western Mediterranean suggesting that the NAO was the dominant modulator of relative variability in precipitation sources. However, as previously suggested other modes such as the Western Mediterranean Oscillation (WeMO) may have altered this overall relationship. In this regard, a decrease in Mediterranean moisture source coincident with a rapid reduction in warm season precipitation during the 4.2 ka BP event at the south-eastern Iberian Peninsula might have been related to negative WeMO conditions.

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Influence of the North Atlantic subpolar gyre circulation on the 4.2 ka BP event

Cited by 14 publications

References 61 publications

Holocene hydrography evolution in the Alboran Sea: a multi-record and multi-proxy comparison

Holocene hydrography evolution in the Alboran Sea: a multi-record and multi-proxy comparison

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Fossil leaf wax hydrogen isotopes reveal variability of Atlantic and Mediterranean climate forcing on the southeast Iberian Peninsula between 6000 to 3000 cal. BP

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