Climatic and land use changes on the NW of Iberian Peninsula recorded in a 1500-year record from Lake Sanabria

Authors

  • Ramon Julià i Brugués
  • José Antonio Luque Marín
  • Santiago Riera i Mora
  • J. A. Alejandro

Abstract

This multi-proxy paleoenvironmental study from Lake Sanabria (NW Iberian Peninsula), based on pollen, diatom, and sedimentology, provides evidences of climatic oscillations attributed to the Late Roman and Medieval Warm Periods as well as the Little Ice Age (LIA). From 440 to 950 AD, the climate was characterized by mild temperatures and a Mediterranean rainfall regime, although climatic cold periods were recorded at ca. 530 and 700. Evidence from pollen indicators of land-use suggests that grazing and farming were widespread activities. This period corresponds to the end of the Roman Warm Period and the Medieval Warm Period. The onset of new climate conditions occurred between 950 and 1100 AD, as minimum values of organic matter, arboreal pollen, diatom concentration, total nitrogen (TN), and grain size indicate low temperatures and a more regular rainfall regime. This period corresponds to the LIA and ended at 1590 AD, when lake productivity tended to recover to previous values in spite of the occurrence of cool events. Total organic carbon, TN, and diatom content covary with the temperature index for the NW Iberia, suggesting that Lake Sanabria was mainly controlled by climate before the industrial period. Since 1920 AD, lake productivity has been mainly influenced by human activity.

Published

2008-09-15