A mid-Holocene climate reconstruction for eastern South America

Abstract

The mid-Holocene (6000 calibrated years before present) is a key period in palaeoclimatology because incoming summer insolation was lower than during the late Holocene in the Southern Hemisphere, whereas the opposite happened in the Northern Hemisphere. However, the effects of the decreased austral summer insolation over South American climate have been poorly discussed by palaeodata syntheses. In addition, only a few of the regional studies have characterised the mid-Holocene climate in South America through a multiproxy approach. Here, we present a multiproxy compilation of mid-Holocene palaeoclimate data for eastern South America. We compiled 120 palaeoclimatological datasets, which were published in 84 different papers. The palaeodata analysed here suggest a water deficit scenario in the majority of eastern South America during the mid-Holocene if compared to the late Holocene, with the exception of northeastern Brazil. Low mid-Holocene austral summer insolation caused a reduced land–sea temperature contrast and hence a weakened South American monsoon system circulation. This scenario is represented by a decrease in precipitation over the South Atlantic Convergence Zone area, saltier conditions along the South American continental margin, and lower lake levels

Groundwater isotopic data as potential proxy for Holocene paleohydroclimatic and paleoecological models in NE Brazil

“…Multi-proxy reconstruction syntheses (e.g., Villalba et al, 2009;Prado et al, 2013a;, have highlighted that the Brazilian North-East (referred to "Nordeste" hereafter) is still very poorly documented. This scarcity of paleodata for Nordeste is probably due to the current geologic and climatic contexts of the area.…”

“…(SA) paleoclimatic reconstruction, available proxies are still considered to be sparse for the area if they are compared to records from Northern Hemisphere (Vuille et al, 2012;Prado et al, 2013a;.…”

“…Over the last two decades, the Holocene climate reconstructions for South-America Monsoon System (SASM) historically poor, have been subject to increasing investigation (Vimieux et al, 2009;Vuille et al, 2012;Prado et al, 2013a;Baker and Fritz, 2015). These reconstructions are based on combination of large-scale numerical models (e.g., IPSL-CM5A-LR, Kageyama et al, [2012] and references therein; MIROC-ESM, Watanabe et al…”

Holocene history of a lake filling and vegetation dynamics of the Serra Sul dos Carajás, southeast Amazonia

“…~ 6 to 4 kyr BP by Cross et al 2000, 8 Guimarães et al 2012, ~6 kyr BP by Prado et al 2013b, ~7 to 3 kyr BP by Guimarães et al 2016). According to Prado et al (2013b), low insolation may be induced a less effective land-sea contrast resulting in less energy available at the surface and diminished ascendant motion. Thus, formation of rain cloud was impaired and drier climate predominated.…”

“…Several paleoclimate records have been demonstrated the influence of precession on precipitation changes along the SAMS domain (e.g. Cruz et al 2005, Wang et al 2006, Cheng et al 2013, Prado et al 2013b). Absolute-dated speleothem oxygen isotope records from Cheng et al (2013) were used to characterize climate changes in western and eastern Amazonia over the past 250,000 and 20,000 yr BP.…”