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Lake Tauca highstand (Heinrich Stadial 1a) driven by a southward shift of the Bolivian High

Martin, L.C.P. ; Blard, P.H. ; Lavé, J. ; Condom, T. ; Prémaillon, M. ; Jomelli, V. ; Brunstein, D. ; Lupker, M. ; Charreau, J. ; Mariotti, V. ; Tibari, B. ; ASTER Team ; Davy, E., Science Advances

Lake Tauca highstand (Heinrich Stadial 1a) driven by a southward shift of the Bolivian High

Martin, L.C.P. ; Blard, P.H. ; Lavé, J. ; Condom, T. ; Prémaillon, M. ; Jomelli, V. ; Brunstein, D. ; Lupker, M. ; Charreau, J. ; Mariotti, V. ; Tibari, B. ; ASTER Team ; Davy, E.

Science Advances, 2018, 4:eaar2514

Abstract :

Heinrich events are characterized by worldwide climate modifications. Over the Altiplano endorheic basin (high trop-ical Andes), the second half of Heinrich Stadial 1 (HS1a) was coeval with the highstand of the giant paleolake Tauca. However, the atmospheric mechanisms underlying this wet event are still unknown at the regional to global scale. We use cosmic-ray exposure ages of glacial landforms to reconstruct the spatial variability in the equilibrium line altitude of the HS1a Altiplano glaciers. By combining glacier and lake modeling, we reconstruct a precipitation map for the HS1a period. Our results show that paleoprecipitation mainly increased along the Eastern Cordillera, whereas the southwestern region of the basin remained relatively dry. This pattern indicates a southward expansion of the east-erlies, which is interpreted as being a consequence of a southward shift of the Bolivian High. The results provide a new understanding of atmospheric teleconnections during HS1 and of rainfall redistribution in a changing climate.

Voir en ligne : http://advances.sciencemag.org/




publié jeudi 13 septembre 2018