1. Department of Geology & Geophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
2. CPMTC, Instituto de Geociências, Universidade Federal de Minas Gerais, Av. Antonio Carlos 6627, Belo Horizonte, Minas Gerais 31270-901, Brazil
3. Instituto de Geociências, Universidade de São Paulo, Rua do Lago 562, São Paulo, SP, 05508-080, Brazil
4. Laboratório de Ciências da Terra, Universidade de Mogi das Cruzes, Av. Cândido Almeida Souza 200, Mogi das Cruzes, SP, Brazil
5. School of Geographical Sciences, University of Bristol, Bristol BS8 1SS, UK
6. Department of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan

Correspondence to: Xianfeng Wang¹ Email: wang0452@umn.edu

Abstract

The tropics are the main source of the atmosphere's sensible and latent heat, and water vapour, and are therefore important for reconstructions of past climate¹. But long, accurately dated records of southern tropical palaeoclimate, which would allow the establishment of climatic connections to distant regions, have not been available. Here we present a 210,000-year (210-kyr) record of wet periods in tropical northeastern Brazil—a region that is currently semi-arid. The record is obtained from speleothems and travertine deposits that are accurately dated using the U/Th method. We find wet periods that are synchronous with periods of weak East Asian summer monsoons², cold periods in Greenland³, Heinrich events in the North Atlantic⁴ and periods of decreased river runoff to the Cariaco basin⁵. We infer that the wet periods may be explained with a southward displacement of the Intertropical Convergence Zone. This widespread synchroneity of climate anomalies suggests a relatively rapid global reorganization of the ocean–atmosphere system. We conclude that the wet periods probably affected rainforest distribution, as plant fossils show that forest expansion occurred during these intermittent wet intervals, and opened a forest corridor^{6, 7, 8} between the Amazonian and Atlantic rainforests.

1. Department of Geology & Geophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
2. CPMTC, Instituto de Geociências, Universidade Federal de Minas Gerais, Av. Antonio Carlos 6627, Belo Horizonte, Minas Gerais 31270-901, Brazil
3. Instituto de Geociências, Universidade de São Paulo, Rua do Lago 562, São Paulo, SP, 05508-080, Brazil
4. Laboratório de Ciências da Terra, Universidade de Mogi das Cruzes, Av. Cândido Almeida Souza 200, Mogi das Cruzes, SP, Brazil
5. School of Geographical Sciences, University of Bristol, Bristol BS8 1SS, UK
6. Department of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan

Correspondence to: Xianfeng Wang¹ Email: wang0452@umn.edu

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