A multi-proxy record of Holocene climatic change in southwestern Spain: the Laguna de Medina, Cadiz

Palaeolimnological data (diatoms, ostracods, foraminifera, molluscs, aquati c pollen and lithology) from a radiocarbon dated sediment core from a salin e lake, the Laguna de Medina, provide the first complete record of Holocene lake-level change for southwest Spain for the last c. 9000 cal. years. The lake has always been relatively shallow but has exhibited marked fluctuati ons in salinity and water depth, especially in the earlier record when osci llations culminate in maximum lake levels from c. 6960-6680 cal. BP (c. 607 0-5830 BP), indicating enhanced early- to mid-Holocene humidity and a mid-H olocene humidity maximum. Prolonged shallowing thereafter reflects in part increased aridity in the later Holocene. Lake desiccation followed by a c. 800-yr phase (zone 2) of major limnological change commencing at c. 8000 ca l. BP (c 7200 BP), and a number of other abrupt desiccation events, are als o noteworthy. The mid-Holocene maximum is consistent with widespread eviden ce for high lake levels around 6000 BP, but the underlying climatic mechani sms are uncertain; there is some evidence it may apply predominantly to the westerly (Atlantic) Peninsula, with earlier maxima in the east. Phases of abrupt limnological change show affinities with African data; as in African takes, the 'zone 2' phase appears to be a response to global change centre d on c. 8.1-8.2 cal. BP. Other correlations made are tenuous, due partly to the lack of preservation in the upper record of some of the proxies used. Other desiccation events currently appear to be of more local significance, reflecting high decadal- to century-scale climatic variability throughout the Holocene.