Hydroclimate changes across the Amazon lowlands over the past 45,000 years
Lawrence Edwards, R.
Auler, Augusto S.
Cruz, Francisco W.
Dorale, Jeffrey A.
Date of Issue2017
Earth Observatory of Singapore
Asian School of the Environment
Reconstructing the history of tropical hydroclimates has been difficult, particularly for the Amazon basin—one of Earth’s major centres of deep atmospheric convection1,2. For example, whether the Amazon basin was substantially drier3,4 or remained wet1,5 during glacial times has been controversial, largely because most study sites have been located on the periphery of the basin, and because interpretations can be complicated by sediment preservation, uncertainties in chronology, and topographical setting6. Here we show that rainfall in the basin responds closely to changes in glacial boundary conditions in terms of temperature and atmospheric concentrations of carbon dioxide7. Our results are based on a decadally resolved, uranium/thorium-dated, oxygen isotopic record for much of the past 45,000 years, obtained using speleothems from Paraíso Cave in eastern Amazonia; we interpret the record as being broadly related to precipitation. Relative to modern levels, precipitation in the region was about 58% during the Last Glacial Maximum (around 21,000 years ago) and 142% during the mid-Holocene epoch (about 6,000 years ago). We find that, as compared with cave records from the western edge of the lowlands, the Amazon was widely drier during the last glacial period, with much less recycling of water and probably reduced plant transpiration, although the rainforest persisted throughout this time.
© 2017 Macmillan Publishers Limited, part of Springer Nature. This is the author created version of a work that has been peer reviewed and accepted for publication by Nature, Macmillan Publishers Limited. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1038/nature20787].