South American climate teleconnections during the last millennium

The Medieval Climate Anomaly (MCA: 800-1300 CE) was the most recent pre-industrial warm interval of European climate, yet it remains less well-known in South America. Various studies from continental and marine late Holocene proxy records from South America show heterogeneous changes during this period. The main goal of this study is to explore for evidence of inter-hemispheric teleconnections and possible responses of South American climate variability to this global change. Sediment cores collected off the central Peruvian coast reveal that the MCA was marked by stronger reducing conditions. Proxy records from the tropical Pacific Ocean show contemporaneous changes indicating cool central and eastern tropical Pacific SSTs during this period. This pattern is consistent with the hypothesis that the dry MCA in the Eastern Pacific region resembled modern La Niña conditions The MCA on the Peru margin was followed by wetter conditions and warming coastal SSTs during the transition into the “Little Ice Age” (LIA). Comparison with other records in the Pacific, Andes region, Cariaco Basin, Northeastern and Southeastern Brazil strongly suggests the meridional change of the ITCZ as the key mechanism explaining the centennial-scale changes.