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Speleothem δ¹³C record suggests enhanced spring/summer drought in south-eastern Spain between 9.7 and 7.8 ka – A circum-Western Mediterranean anomaly?

Budsky, Alexander, Scholz, Denis, Wassenburg, Jasper A, Mertz-Kraus, Regina, Spötl, Christoph, Riechelmann, Dana FC, Gibert, Luis, Jochum, Klaus Peter, Andreae, Meinrat O
TheHolocene 2019 v.29 no.7 pp. 1113-1133
Holocene epoch, atmospheric circulation, atmospheric precipitation, drought, monsoon season, oxygen, spring, summer, surface water temperature, vegetation, Italy, Mediterranean region, Spain
South-eastern Spain is one of the driest regions in Europe and thus, prone to drought. Terrestrial climate records covering the late Glacial and Holocene from this area are sparse. Here, we present a flowstone record from Cueva Victoria, south-eastern Spain, which covers the late Glacial (15 ka) to the mid-Holocene (7 ka) including the Younger Dryas (YD). Between the onset of the Bølling/Allerød (B/A) and the early Holocene, flowstone δ¹⁸O values progressively decrease in accordance with sea-surface temperatures in the Alboran Sea, indicating an increase in precipitation in south-eastern Spain and a supra-regional signal of North Atlantic temperature change. At the same time, decreasing δ¹³C values suggest progressively increasing precipitation and vegetation density. This trend is interrupted by both colder and drier conditions during the YD. Between 9.7 ± 0.3 and 7.8 ± 0.2 ka, a large positive excursion of the δ¹³C values indicates a strong reduction in vegetation density, probably as a consequence of very dry spring/summer conditions. In combination with the continuously low speleothem δ¹⁸O values and a nearly unchanged growth rate, this suggests increased seasonality (i.e. drier spring/summer conditions, but not a strong reduction in annual precipitation). This is consistent with several other climate records from the Western Mediterranean region, showing that the Western Mediterranean realm (Spain, Italy) experienced pronounced spring/summer drought during this time interval. Interestingly, the timing of this dry period coincided with the African Humid Period. This may be part of a teleconnection with the North African Monsoon via the Hadley cell circulation.