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Abrupt climate change in northern Iberia: new results from speleothem records
Ana Moreno
Jeudi 21/12/2017, 11:00-12:00
Bât. 701, P. 17C, LSCE Orme des Merisiers

The western Mediterranean region has demonstrated a tight connection with changes in the North Atlantic circulation. Such a connection is here explored through a multi-proxy study of cave speleothems, later integrated with lacustrine records and marine sediments to reflect climate conditions along the Iberian Peninsula. Interpretation of isotopes is supported by (i) a detailed monitoring survey in the studied caves, (ii) the good overlapping of some recent stalagmites with the observational period and (iii) the study of rainfall isotopic variability along a W-E transect covering from and area under typical Atlantic climate to fully Mediterranean sites. In this seminar, I will focus on different climate transitions, such as Termination I and III, when high-resolution speleothem records provide information on the timing and internal structure of these periods. Thus, two hydrological phases within the Greenland Stadial 1 (GS-1) cold event (12.8−11.7 ka B.P.) in the Pyrenees are described and linked to changes in the Atlantic overturning circulation. New speleothem results from the Iberian Range covering Termination III reveal the sequence of abrupt stadial events in close analogy to the Asian Monsoon changes reconstructed from Chinese speleothems. During last glacial cycle, the high sensibility of the Iberian Peninsula climate conditions to changes in temperature or ice volume in the North Atlantic region was revealed by previous marine sediments where D/O cycles were very evident. However, the response of a terrestrial area under the influence of Mediterranean climate remained to be investigated. I will present two new speleothem records, one from the Pyrenees and other from the Iberian Range, that allow exploring past climate variability since last glacial inception. Temperature and humidity changes along the Holocene show a more complex pattern. Contrarily, for the last 2000 years and supported by a good overlapping during the observational period of d18O from actively growing modern stalagmites and air temperature, a reconstruction resulting from compiling seven stalagmites from three different caves in the Pyrenees is presented.

Contact : Juliette Lathiere
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