The South American Monsoon System is responsible for the majority of precipitation in the continent, especially over the Amazon and the tropical savannah, known as ‘Cerrado’. Compared to the extensively studied subtropical and temperate regions the effect of the Medieval Climate Anomaly (MCA) on the precipitation over the tropics is still poorly understood. Here, we present a multiproxy paleoprecipitation reconstruction showing a consistent change in the hydrologic regime during the MCA in the eastern Amazon and ‘Cerrado’, characterized by a substantial transition from humid to drier conditions during the Early (925-1150 C.E.) to Late-MCA (1150-1350 C.E.). We compare the timing of major changes in the monsoon precipitation with the expansion and abandonment of settlements reported in the archeological record. Our results show that important cultural successions in the pre-Columbian Central Amazon, the transition from Paredão to Guarita phase, are in agreement with major changes in the hydrologic regime. Phases of expansion and, subsequent abandonment, of large settlements from Paredão during the Early to Late-MCA are coherent with a reduction in water supply. In this context we argue that the sustained drier conditions during the latter period may have triggered territorial disputes with Guarita leading to the Paredão demise.
Bibliographical noteFunding Information:
We thank A. Barros, Y. Ning and I. Pedron for their support during the stable isotope data acquisition at the University of São Paulo and dating analyses at the Xi’an Jiaotong University. We thank A. Auler, S. Carolin, J. Watling, V. Novello and an anonymous reviewer for their suggestions regarding the manuscript. We are grateful to Instituto Brasileiro do Meio Ambiente/Instituto Chico Mendes de Conservação da Biodiversidade (IBAMA/ ICMBio) for permission to collect stalagmite samples. This work was supported by FAPESP (Grants 2017/50085-3 PIRE NSF-FAPESP and 2016/02656-9), CAPES (AUXPE PREMIO 2043/2014 to R.A.S. and Master Fellowship to V.A.), CLIMATE-PRINT-UFF Project (CAPES grant 88887.310301/2018-00), NSF grant OISE-1743738 and CNPq (Grants 423573/2018-7 and 426258/2016-9).