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North-Central - 52nd Annual Meeting

Paper No. 1-2
Presentation Time: 8:20 AM

CHANGES IN HYDROCLIMATE IN IBERIA IN THE LAST 1200 YEARS: INSIGHTS FROM SPELEOTHEM RECORDS FROM WESTERN PORTUGAL


THATCHER, Diana L., Department of Geological and Atmospheric Sciences, Iowa State University, 253 Science I, Ames, IA 50011, WANAMAKER Jr., Alan D., Department of Geological and Atmospheric Sciences, Iowa State University, 253 Science Hall, 2237 Osborn Drive, Ames, IA 50011, DENNISTON, Rhawn F., Department of Geology, Cornell College, Mount Vernon, IA 52314, ASMEROM, Yemane, Earth & Planetary Sciences, University of New Mexico, 200 Yale Blvd., Northrop Hall, Albuquerque, NM 87131, UMMENHOFER, Caroline, Woods Hole Oceanographic Institution, Falmouth, MA 02543, POLYAK, Victor J., Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131, HASIUK, Franciszek, Geological and Atmospheric Sciences, Iowa State Unversity, 253 Science Hall, 2237 Osborn Drive, Ames, IA 50011, HAWS, Jonathan A., Anthropology, University of Louisville, Louisville, KY 40292 and GILLIKIN, David P., Geology Department, Union College, Schenectady, NY 12308

Many proxy records from coastal Atlantic Europe and northwest Africa provide evidence of distinct hydroclimate regimes in the last millennium; however several aspects regarding the spatial and temporal dynamics of hydroclimate, especially during the Medieval Climate Anomaly (MCA; AD 850-1250), and the driving mechanisms, including the North Atlantic Oscillation (NAO), still remain open. Presented here are continuous, precisely dated, and sub-decadally-resolved geochemical time series from two stalagmites from Buraca Gloriosa (BG) cave, western Portugal, situated within the center of the Azores High at the southern node of the NAO, which preserves evidence of regional hydroclimate from approximately AD 800 to the present. The BG stalagmite records, along with a Spanish stalagmite record, and Moroccan hydroclimate records, each contain evidence for enhanced aridity during the MCA, a fairly abrupt transition to a wetter Little Ice Age (LIA; ~AD 1250-1850), and a gradual return to more arid conditions during Modern Climate. Our proxy data reveal that substantial short-term hydroclimate variability characterized the last 1200 years. They support the hypothesis that while an intensified, semi-persistent subtropical high (and likely positive NAO state) characterized much of the MCA, the NAO remained variable over this time period. Climate model results also suggest that the Azores High pressure system both migrated southward and weakened from the MCA into the LIA.

Session No. 1

T3. Climate Reconstructions from Cave Deposits
Monday, 16 April 2018: 8:00 AM-12:00 PM
Benton Auditorium (Scheman Building )
Geological Society of America Abstracts with Programs. Vol. 50, No. 4
doi: 10.1130/abs/2018NC-311958
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