A multiproxy study of sediment cores from Zoñar Lake (37°29′00″N, 4°41′22″W, 300 m a.s.l.) supported by 11 ¹⁴C AMS dates provides the first high-resolution centennial-scale reconstruction of past humidity changes in southern Spain during the last 4000 years. Arid periods occurred prior to 2.9 cal. kyr BP and during 1.3—0.6 cal. kyr BP (`Mediaeval Climate Anomaly'). The most humid period occurred during 2.6—1.6 cal. kyr BP encompassing the late Iron Age—Iberian and Roman epochs. Two humid periods of lower intensity occurred between 0.8 and 0.6 cal. kyr BP (AD 1200—1400) and about 400 cal. yr BP (around AD 1600) coinciding with the onset of the `Little Ice Age'. Humid conditions are synchronous with a decline in solar output and seem to correspond to atmospheric patterns similar to negative NAO phases. Arid conditions show better correlation with northern Africa climate evolution, suggesting a possible link to subtropical dynamics. The geographic location of Zoñar Lake and the robust chronology provides an opportunity to improve our understanding of the climate evolution in mid latitudes during the late Holocene and to evaluate subtropical and high latitude factors in Mediterranean climate evolution.

A combination of marine (Alboran Sea cores, ODP 976 and TTR 300 G) and terrestrial (Zoñar Lake, Andalucia, Spain) geochemical proxies provides a high-resolution reconstruction of climate variability and human influence in the southwestern Mediterranean region for the last 4000 years at inter-centennial resolution. Proxies respond to changes in precipitation rather than temperature alone. Our combined terrestrial and marine archive documents a succession of dry and wet periods coherent with the North Atlantic climate signal. A dry period occurred prior to 2.7 cal ka BP – synchronously to the global aridity crisis of the third-millennium BC – and during the Medieval Climate Anomaly (1.4–0.7 cal ka BP). Wetter conditions prevailed from 2.7 to 1.4 cal ka BP. Hydrological signatures during the Little Ice Age are highly variable but consistent with more humidity than the Medieval Climate Anomaly. Additionally, Pb anomalies in sediments at the end of the Bronze Age suggest anthropogenic pollution earlier than the Roman Empire development in the Iberian Peninsula. The Late Holocene climate evolution of the in the study area confirms the see-saw pattern between the eastern and western Mediterranean regions and the higher influence of the North Atlantic dynamics in the western Mediterranean.

The Iberian–Roman Humid Period (IRHP, 2600–1600 cal yr BP), is the most humid phase of the last 4000 yr in southern Spain as recorded in the sedimentary sequence of Zoñar Lake (37°29′00″N, 4°41′22″ W, 300 m a.s.l.). A varve chronology supported by several AMS¹⁴C dates allows study of the lake evolution at annual scale in response to human impact and climate changes. There are four climate phases within this period: i) gradual transition (2600–2500 yr ago, 650–550 BC) from a previous arid period; ii) the most humid interval during the Iberian–Early Roman Epoch (2500–2140 yr ago, 550–190 BC); iii) an arid interval during the Roman Empire Epoch (2140–1800 yr ago, 190 BC AD 150); and iv) a humid period synchronous with the decline of the Roman Empire (1800–1600 yr ago, AD 150–350). Varve thickness and geochemical proxies show a multi-decadal cyclicity similar to modern North Atlantic Oscillation (NAO) (60, 20 years) and solar variability cycles (11 yr). The timing and the structure of this humid period is similar to that described in Eastern Mediterranean and northern European sites and supports the same large-scale climate control for northern latitudes and the Mediterranean region.