CLIMATE VARIABILITY AND ANTHROPOGENIC ACTIONS AS DRIVERS FOR AEOLIAN ACTIVITY DURING THE LAST MILLENNIUM IN SOUTH-WESTERN EUROPE

Um caso de estudo da costa portuguesa

Abstract

The building of dunes and sand drifts along the European coastline are generally related to climatic variability and sea-level fluctuation. The last phase of dunes formation in south-western Europe coincides with the Little Ice Age (LIA) period characterized by pronounced climate variability. Historical sources retrieved from archives also report sand-drift events along the Portuguese coast. The sand invaded many agricultural fields, and settlements, forcing the inhabitants to move elsewhere. The article explores the temporal relationships between sand drift occurrences and climate, as a principal trigger or coastal dune migration. We used historical sources about sand-drift events as documentary proxies to infer the past climate variability on the Portuguese coast. Three spatial scales of climate variability were considered: i) the global climatic variability induced by the cold abrupt events over the last Millennium (LIA); ii) the regional (mesoscale) climate variability (NAO index), and iii) the local climate variability (extreme meteorological events). The paleoclimatic interpretation indicates that drifts in Portugal are related to both NAO modes, providing new insights into coastal dunes dynamics, as a response to natural drivers. However, the analysis of human activity on the coast also allowed us to better understand the relation of the local populations with their environments, highlighting those anthropogenic actions caused an additional disturbance on coastal dune dynamics.