Southern Annular Mode-like changes in southwestern Patagonia at centennial timescale over the last three millennia

PATRICIO MORENO; ISABEL VILANOVA; RODRIGO VILLA-MARTINEZ; GARREAUD, R.D; ROJAS, M.; DE POL-HOLZ, R.

NATURE COMMUNICATIONS

Macmillan Publishers Limited

Lugar: London; Año: 2014 vol. 5375 p. 1 - 7

2041-1723

Late twentieth-century instrumental records reveal a persistent southward shift  of  the Southern Westerly Winds during austral summer and autumn associated with a positive trend of the Southern Annular Mode (SAM) and contemporaneous with glacial recession, steady increases in atmospheric temperatures and CO2 concentrations at a global scale. However, despite the clear importance of the SAM importance in the modern/future climate very little is known about its behavior during pre-Industrial times. Here we present a stratigraphic record from Lago Cipreses (51°S), southwestern Patagonia, that reveals recurrent ~200-yr long dry/warm phases over the last three millennia, which we interpret as positive SAM-like states. These correspond in timing with the Industrial revolution, the Mediaeval Climate Anomaly, the Roman and Late Bronze Age Warm Periods, and alternate with cold/wet multi-centennial phases in European paleoclimate records. We conclude that SAM-like changes at centennial timescales in southwestern Patagonia represent in-phase interhemispheric coupling of paleoclimate over the last 3000 years through atmospheric  teleconnections.