Millennial-scale precipitation variability over Easter Island (South Pacific) during MIS 3: inter-hemispheric teleconnections with North Atlantic abrupt cold events
O. Margalef1, I. Cacho2, S. Pla-Rabes1, N. Cañellas-Boltà3, J. J. Pueyo2, A. Sáez2, L. D. Pena2, B. L. Valero-Garcés4, V. Rull3, and S. Giralt31Ecological Research Center and Forestry Applications (CREAF), Campus de Bellaterra (UAB) 08193 Cerdanyola del Vallès, Barcelona, Spain 2Faculty of Geology, Universitat de Barcelona, Martí Franquès s/n, 08028 Barcelona, Spain 3Institute of Earth Sciences Jaume Almera (ICTJA-CSIC), Sedimentary Geology and Geohazards, Lluís Solé i Sabarís s/n, 08028 Barcelona, Spain 4Pyrenean Institute of Ecology (IPCSIC), Avda, de Montañana 1005, 50059 Zaragoza, Spain
Received: 13 Mar 2015 – Accepted for review: 23 Mar 2015 – Discussion started: 17 Apr 2015
Abstract. Marine Isotope Stage 3 (MIS 3, 59.4–27.8 kyr BP) is characterized by the occurrence of rapid millennial-scale climate oscillations known as Dansgaard–Oeschger cycles (DO) and by abrupt cooling events in the North Atlantic known as Heinrich events. Although both the timing and dynamics of these events have been broadly explored in North Atlantic records, the response of the tropical and subtropical latitudes to these rapid climatic excursions, particularly in the Southern Hemisphere, still remains unclear. The Rano Aroi peat record (Easter Island, 27° S) provides a unique opportunity to understand atmospheric and oceanic changes in the South Pacific during these DO cycles because of its singular location, which is influenced by the South Pacific Anticyclone (SPA), the Southern Westerlies (SW), and the Intertropical Convergence Zone (ITCZ) linked to the South Pacific Convergence Zone (SPCZ). The Rano Aroi sequence records 6 major events of enhanced precipitation between 38 and 65 kyr BP. These events are compared with other hydrological records from the tropical and subtropical band supporting a coherent regional picture, with the dominance of humid conditions in Southern Hemisphere tropical band during Heinrich Stadials (HS) 5, 5a and 6 and other Stadials while dry conditions prevailed in the Northern tropics. This antiphased hydrological pattern between hemispheres has been attributed to ITCZ migration, which in turn might be associated with an eastward expansion of the SPCZ storm track, leading to an increased intensity of cyclogenic storms reaching Easter Island. Low Pacific Sea Surface Temperature (SST) gradients across the Equator were coincident with the here-defined Rano Aroi humid events and consistent with a reorganization of Southern Pacific atmospheric and oceanic circulation also at higher latitudes during Heinrich and Dansgaard–Oeschger stadials.
Margalef, O., Cacho, I., Pla-Rabes, S., Cañellas-Boltà, N., Pueyo, J. J., Sáez, A., Pena, L. D., Valero-Garcés, B. L., Rull, V., and Giralt, S.: Millennial-scale precipitation variability over Easter Island (South Pacific) during MIS 3: inter-hemispheric teleconnections with North Atlantic abrupt cold events, Clim. Past Discuss., 11, 1407-1435, doi:10.5194/cpd-11-1407-2015, 2015.