Multi-decadal climate variability in southern Iberia during the mid- to late-Holocene

Abstract

Abstract. To assess the regional multi-decadal to multi-centennial climate variability at the southern Iberian Peninsula during the mid- to late- Holocene transition multi-proxy records of two marine sediment cores were established for two sites in the Alboran Sea (ODP-161-976A) and the Gulf of Cadiz (GeoB5901-2). High-resolution records of organic geochemical proxies and planktic foraminiferal assemblages are used to decipher precipitation and vegetation changes as well as the sea surface conditions with respect to Sea Surface Temperature (SST) and marine primary productivity (MPP). n-Alkane records as a proxy for precipitation changes suggest a series of six distinct drought events at 5.4 ka BP, from ca. 5.1 ka BP to 4.9 ka BP, from 4.8 to 4.7 ka BP, at 4.6 ka BP, from 4.4 to 4.3 ka BP and, from 3.8 to 3.7 ka BP. Each drought event is associated with a major vegetation change towards higher proportions of C4 vegetation. The drought events are further accompanied by annual and spring/ winter SST warming as well as decreasing MPP in the Alboran Sea. Altogether, the close correlation of the observed droughts with North Atlantic Oscillation (NAO)-like variability suggests changes in the atmospheric circulation as important driving mechanism of terrestrial and oceanic variability at southern Iberia and the Alboran Sea, respectively. Sea surface variability in the Gulf of Cadiz, instead, is intimately linked to the North Atlantic Bond Events. In particular, during Bond Events 3 and 4 a pronounced increase in seasonality is found.

Holocene climate variability of the Western Mediterranean: Surface water dynamics inferred from calcareous plankton assemblages

“…These results suggest that, with the exception of the interval between 10.2 and 8.7 ka, our SST record shows values comparable with those derived from the alkenone-SST at the same site (Martrat et al, 2014), with the foram-based SST from other nearly records (Pérez-Folgado et al, 2003;Schirrmacher et al, 2019), and with the present-day SST in the region (Locarnini et al, 2013). On the basis of these considerations, only the last 8.6 kyr record has been considered for the climate interpretation.…”

“…Planktic foraminifera assemblages were used to reconstruct annual, summer (July to September) and winter (January to March) SST with the modern analog technique non distance-weighted SIMMAX 28 and 10 analogs (Pflaumann et al, 1996). Considering that the study site is influenced by Atlantic and Mediterranean ocean circulation, following Schirrmacher et al (2019), we use the combined North Atlantic core-top database (Kucera et al, 2005;Salgueiro et al, 2010Salgueiro et al, , 2014 and the Mediterranean database (Hayes et al, 2005), and the root mean square error of both annual and seasonal SST reconstructions is about 1.3ºC (Schirrmacher et al, 2019).…”

“…Such conditions could probably represent the response to changes in hydrological conditions in the adjacent Iberian basin, related to the reduction of meltwater discharge in the North Atlantic (Bond et al, 2001). In the Gulf of Cádiz, according to Schirrmacher et al (2019), larger seasonal SST contrasts, during the Holocene, are related to periods of enhanced iceberg discharge; the northward heat transport was blocked due to freshwater forcing in the North Atlantic resulting in colder winter temperatures and higher summer temperatures due to a seasonal northward migration of Intertropical Convergence Zone (ITCZ). This mechanism is similar to the one proposed by Repschläger et al (2017) for the early Holocene, when reinforcements of northward heat transport and migration of Subtropical Gyre is found during periods of weak north Atlantic meltwater discharge.…”

The concept of socio-environmental transformations in prehistoric and archaic societies in the Holocene: An introduction to the special issue

“…Focus 3 Socio-environmental components of change concentrates on specific factors or components of change, be they climate and human adaptation strategies (Butruille et al, 2017; Groß et al, this issue; Hinz et al, this issue; Schirrmacher et al, 2019); vegetation and faunal change, human impact, and resource management (Dal Corso et al, this issue, 2018; Feeser et al, this issue; Sommer et al, 2018; Wieckowska-Lüth et al, 2018); the dynamics of soils and erosion processes, demography, mobility and diseases (Capuzzo et al, 2018; Feeser et al, this issue; Fuchs et al, this issue; Furholt, 2017; Krause-Kyora et al, 2018; Müller and Diachenko, 2019); the development and impacts of subsistence practices (Filatova et al, 2019; Filipović et al, this issue, 2018; Jahns et al, 2018) or the social role of technologies and innovations (Bech et al, 2018; Brozio et al, this issue; Kirleis, 2019; Schaefer-Di Maida and Kneisel, this issue).…”

Unravelling the Holocene environmental history of south-western Iberia through a palynological study of Lake Medina sediments

“…The mid to late Holocene is characterized by progressive aridification of, for example, the IP because of lowered summer insolation (Carrión et al, 2003; Fletcher and Zielhofer, 2013; Mayewski et al, 2004; Morellón et al, 2009; Schirrmacher et al, 2019). Xerothermophilous shrubland pollen of Olea europaea and Phillyrea within core CO1313 indicate warm-temperate climate conditions.…”