Hydrological evidence for a North Atlantic oscillation during the Little Ice Age outside its range observed since 1850
C. Martín-Puertas1, I. Dorado-Liñán1, A. Brauer1, E. Zorita2,3, B. L. Valero-Garcés4, and E. Gutierrez51Helmholtz-Zentrum Potsdam, Deutsches GeoForschungZentrum, Sektion 5.2 Klimadynamik und Landschaftsentwicklung, Telegrafenberg, 14473 Potsdam, Germany 2Helmholtz-Zentrum Geesthacht, Geesthacht, Germany 3Bert Bolin Centre for climate Research, University of Stockholm, Sweden. 4Instituto Pirenaico de Ecología CSIC. Apdo 13034, 50080, Zaragoza, Spain 5Universitat de Barcelona. Departament d'Ecologia. Diagonal 643, 08028, Barcelona, Spain
Received: 15 Nov 2011 – Accepted for review: 19 Nov 2011 – Discussion started: 02 Dec 2011
Abstract. An annual-resolved precipitation reconstruction for the last 800 yr in Southern Spain has been performed using stable carbon isotope (δ13C) of Pinus nigra tree rings. The reconstruction exhibits high- to low-frequency variability and distinguishes a Little Ice Age (LIA, AD 1350–1850) characterized by lower averaged rainfall than both in the transition from the Medieval Climate Anomaly to the LIA and in the 20th century. The driest conditions are recorded during the Maunder solar Minimum (mid 17th–early 18th centuries), in good agreement with the Spanish documentary archive. Similar linkage between solar activity (maximum/minimum) and precipitation (increase/decrease) is observed throughout the entire LIA. Additionally, the relationship between the hydrological pattern in the Iberian Peninsula and Morocco during the LIA suggests different spatial distribution of precipitation in the south-eastern sector of the North Atlantic region such as it is known currently. Whereas in the instrumental record the precipitation evolves similarly in both regions and opposite to the North Atlantic oscillation (NAO) index, the coldest periods of the LIA shows a contrasting pattern with drier conditions in the South of Spain and wetter in Northern Africa. We suggest an extreme negative NAO conditions, accompanied by a southward excursion of the winter rainfall band beyond that observed in the last century, can explain this contrast. The sustained NAO conditions could have been triggered by solar minima and higher volcanic activity during the LIA.
Martín-Puertas, C., Dorado-Liñán, I., Brauer, A., Zorita, E., Valero-Garcés, B. L., and Gutierrez, E.: Hydrological evidence for a North Atlantic oscillation during the Little Ice Age outside its range observed since 1850, Clim. Past Discuss., 7, 4149-4171, doi:10.5194/cpd-7-4149-2011, 2011.