Evidence of a prolonged drought ca. 4200 yr BP correlated with prehistoric settlement abandonment from the Gueldaman GLD1 Cave, Northern Algeria

Abstract

Abstract. Middle Holocene cultures have been widely studied around the Eastern-Mediterranean basin in the last 30 years and past cultural activities have been commonly linked with regional climate changes. However, in many cases such linkage is equivocal, in part due to existing climatic evidence that has been derived from areas outside the distribution of ancient settlements, leading to uncertainty from complex spatial heterogeneity in both climate and demography. A few high-resolution well-dated paleoclimate records were recently established using speleothems in the Central and Eastern-Mediterranean basin, however, the scarcity of such records in the western part of the Mediterranean prevents us from correlating past climate evolutions across the basin and deciphering climate–culture relation at fine timescales. Here we report the first decadal-resolved Mid-Holocene climate proxy records from the Western-Mediterranean basin based on the stable carbon and oxygen isotopes analyses of two U/Th dated stalagmites from the Gueldaman GLD1 Cave in Northern Algeria. Comparison of our records with those from Italy and Israel reveals synchronous (multi) centennial dry phases centered at ca. 5600, ca. 5200 and ca. 4200 yr BP across the Mediterranean basin. New calibrated radiocarbon dating constrains reasonably well the age of rich anthropogenic deposits (e.g., faunal remains, pottery, charcoal) excavated inside the cave, which allows the comparison between in situ evidence of human occupation and of climate change. This approach shows that the timing of a prolonged drought at ca. 4400–3800 yr BP blankets the onset of cave abandonment shortly after ca. 4403 cal yr BP, supporting the hypothesis that a climate anomaly may have played a role in this cultural disruption.

The 4.2 ka BP Event in the Mediterranean region: an overview

“…Changes in circulation are also suggested by exotic pollen of cedar, arriving from north Africa, in some pollen successions of central Italy (e.g., Magri and Parra, 2002). Between approximately 4.4 and 4.0 ka, there is evidence for an increase in storm activity, as documented by several records in the central Mediterranean (Sabatier et al, 2012;Kaniewski et al, 2016;Marriner et al, 2017), possibly suggesting an increase of occasional strong southward incursion of westerlies. This is not in contrast with a trend towards increased flooding in central Tunisia in this period correlated with a colder period in the North Atlantic ( Fig.…”

“…8c and 10 seems to find some similarity with the reconstruction proposed by Dermody et al (2012) during Roman time. According to Der- (Berger and Loutre, 1991); NAO index (Olsen et al, 2011); storm activity in the Gulf of Lion (Sabatier et al, 2012); Renella Cave ; Mohos peat dust flux (Longman et al, 2017); Scȃrişoara Ice Cave, d excess in the ice cave (Perşoiu et al, 2017); probability flood frequency from north Tunisia (Zielhofer and Faust, 2008); Sidi Ali dust flux (Zielhofer et al, 2017b); clastic input at Petit Lac (Brisset et al, 2013); Gemini Lake July temperature (Northern Apennines) (Samartin et al, 2017); Alìmini Pìccolo arboreal pollen (AP %) record (Di Rita and Magri, 2009); Calderone glacier expansion (Zanchetta et al, 2012a); Qarun Lake (Marks et al, 2018). Figure 10.…”

Reply to Anonymous Referee #2

“…(1) Marine core MD95-2015 (this study); (2) marine core MD99-2275 (this study); (3) marine core GS06-144 08GC (Mjell et al, 2015); (4) marine core RAPiD-12-1K (Thornalley et al, 2009); (5) marine core P-013 (Solignac et al, 2004); (6) marine core JM96 1207 (Solignac et al, 2006); (7) ice core GISP2 (O'Brien et al, 1995); (8) marine core Fox05R/04G (Andresen et al, 2012); (9) marine core MD95-2011 (Berner et al, 2011); (10) marine core KSGC-31 ; (11) core PB06 from the Palavasian Lagoon (Azuara et al, 2015); (12) speleothem from Renella Cave (Zanchetta et al, 2016); (13) speleothem from Gueldaman Cave (Ruan et al, 2016). Subpolar and subtropical gyres as well as main surface currents in the North Atlantic are also shown.…”

“…In the last decade, an increasing number of high-resolution proxy records has provided a more comprehensive description of this event (Weiss, 2016). In the Mediterranean region, climate reconstructions have highlighted a drastic reduction in precipitation and extreme climate conditions prevailing during this period, mostly during the winter season Fohlmeister et al, 2013;Zanchetta et al, 2016;Cheng et al, 2015;Ruan et al, 2016;Jalali et al, 2016;Finné et al, 2017;Bini et al, 2019, this issue and references therein). According to Weiss (2015), a 30 %-50 % reduction in precipitation delivered by the Mediterranean westerlies during the 4.2 ka BP event led to extreme dryness in the Middle East and central Asia.…”

Reply to Anonymous Referee #3

“…(f) δ 18 O record obtained from Gueldaman Cave stalagmite (site 13, Fig. 1) (Algeria;Ruan et al, 2016). A 50-year binning is applied to reduce the effect of proxy reconstruction error (thick lines).…”