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Supplemental material, sj-pdf-1-hol-10.1177_0959683620988053 for Climate and land-use effects on hydrological and vegetation signals during the last three millennia: Evidence from sedimentary leaf waxes in southwestern Morocco by Asmae Baqloul, Enno Schefuß, Martin Kölling, Lydie Dupont, Jeroen Groeneveld, Xueqin Zhao, Hanane Reddad, Lhoussaine Bouchaou and Ilham Bouimetarhan in The Holocene

Lipid biomarker proxies from terrigenous sediments have been extensively used to understand variations in paleoenvironmental conditions, but many of the mechanisms affecting these proxies during riverine transport are still poorly understood. Here, we analyze glycerol dialkyl glycerol tetraether (GDGT) distributions and n-alkane isotopic compositions of soils and sediments from the Amazon River Basin. Our dataset includes suspended sediments of the Amazon River and its main tributaries, as well as soils and sediments of the Xingu River, a large clearwater tributary draining the easternmost part of the Amazon River Basin. Our sampling design aimed at understanding the processes behind spatially distinct GDGT distributions and n-alkane isotopic signatures across lowland Amazonia. Gradual changes in the fractional abundances of isoprenoid GDGTs and in 5- and 6- methyl branched GDGT ratios in suspended sediments of the Amazon River towards its mouth suggest that riverine production is an increasingly important control on the distribution of GDGTs in the lower parts of the system, while values from the western parts are more in line with a dominant soil sourcing. In the Xingu River, indices based on the fractional abundances of branched GDGTs and long-chain n-alkanes demonstrate a strong contribution of terrestrial organic material during the high-water season and an important aquatic component during low-water season. Meanwhile, average stable carbon (δ13C) and hydrogen (δD) isotopic signatures of long-chain n-alkanes in soils, riverbed and suspended sediments of the Xingu River are similar and reinforce the relatively conservative behaviour of these proxies within large river systems. The average compound-specific δ13C signatures of sediments in the Xingu River are within the expected range for C3 vegetation and do not seem to capture the signals from the nearby deforested areas. n-Alkanes δD signals in the Xingu Basin are similar to values obtained in the Amazon River mouth and indicate that n-alkanes sourced from easternmost Amazonian lowlands may predominate over signals from western areas. ISSN:0009-2541 ISSN:1872-6836

Southern Africa is located at the interface of sub-tropical and temperate climate zones as well as between two major warm and cold ocean current systems (Agulhas and Benguela), respectively. This makes it a key region for understanding global climate dynamics and highly sensitive to future climatic change. A growing number of paleo-archives have revealed small-scale climatic dipoles in this region and the driving mechanisms of the complex climatic variability often in this region remain unclear. Several regional studies have suggested a synchronicity with the southern hemisphere and thus inferred a direct insolation forcing while others have observed a synchronicity with northern hemispheric climate and associated this with a teleconnection mechanism. In order to decipher the complex climatic processes affecting this region it is necessary to integrate on- and offshore paleo-archives as well as various paleo-environmental indicators (proxies). For the correct interpretation of the various proxies a source to sink approach is necessary determining the origin of the different terrestrial sedimentary components and their potential alterations during transport and deposition. With a focus on marine and lacustrine sedimentary archives along the west, south, and east coast of southern Africa we are now able to reconstruct Late Quaternary climate variability on regional scales. We propose a new conceptual model describing latitudinal shifts of rainfall zones as tropical and temperate climate systems shift over glacial and interglacial cycles. New insights allow us to resolve some of the apparent contradictions between paleoclimate records from the region.

Supplementary Material, Supplementary_Figure_1 for Holocene hydrologic and vegetation developments in the Orange River catchment (South Africa) and their controls by Nicole Burdanowitz, Lydie Dupont, Matthias Zabel and Enno Schefuß in The Holocene

Supplemental material, Supplementary_file_for_The_Holocene for Late-Holocene oceanic variability in the southern Benguela region driven by interplay of upwelling, fluvial discharge, and Agulhas leakage by Xueqin Zhao, Lydie Dupont, Enno Schefuß, Robyn Granger and Gerold Wefer in The Holocene

Changes in heat transport associated with fluctuations in the strength of the Atlantic meridional overturning circulation (AMOC) are widely considered to affect the position of the Intertropical Convergence Zone (ITCZ), but the temporal immediacy of this teleconnection has to date not been resolved. Based on a high‐resolution marine sediment sequence over the last deglaciation, we provide evidence for a synchronous and near‐linear link between changes in the Atlantic interhemispheric sea surface temperature difference and continental precipitation over northeast Brazil. The tight coupling between AMOC strength, sea surface temperature difference, and precipitation changes over northeast Brazil unambiguously points to a rapid and proportional adjustment of the ITCZ location to past changes in the Atlantic meridional heat transport.

The initiation of the Benguela upwelling has been dated to the late Miocene, but estimates of its sea surface temperature evolution are not available. This study presents data from Ocean Drilling Program (ODP) Site 1085 recovered from the southern Cape Basin. Samples of the middle Miocene to Pliocene were analyzed for alkenone-based (U37 K", SSTUK) and glycerol dialkyl glycerol tetraether (GDGT) based (TEX86, TempTEX) water temperature proxies. In concordance with global cooling during the Miocene, SSTUK and TempTEX exhibit a decline of about 8°C and 16°C, respectively. The temperature trends suggest an inflow of cold Antarctic waters triggered by Antarctic ice sheet expansion and intensification of Southern Hemisphere southeasterly winds. A temperature offset between both proxies developed with the onset of upwelling, which can be explained by differences in habitat: alkenone!producing phytoplankton live in the euphotic zone and record sea surface temperatures, while GDGT!producing Thaumarchaeota are displaced to colder subsurface waters in upwelling!influenced areas and record subsurface water temperatures. We suggest that variations in subsurface water temperatures were driven by advection of cold Antarctic waters and thermocline adjustments that were due to changes in North Atlantic deep water formation. A decline in surface temperatures, an increased offset between temperature proxies, and an increase in primary productivity suggest the establishment of the Benguela upwelling at 10 Ma. During the Messinian Salinity Crisis, between 7 and 5 Ma, surface and subsurface temperature estimates became similar, likely because of a strong reduction in Atlantic overturning circulation, while high total organic carbon contents suggest a “biogenic bloom.” In the Pliocene the offset between the temperature estimates and the cooling trend was reestablished.

Author Posting. © The Author(s), 2016. This is the authors version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature Geoscience 9 (2016): 687-690, doi:10.1038/ngeo2778. The age of organic material discharged by rivers provides information about its sources and carbon cycling processes within watersheds. While elevated ages in fluvially-transported organic matter are usually explained by erosion of soils and sediments deposits it is commonly assumed that mainly young organic material is discharged from flat tropical watersheds due to their extensive plant cover and rapid carbon turnover. Here we present compound-specific radiocarbon data of terrigenous organic fractions from a sedimentary archive offshore the Congo River in conjunction with molecular markers for methane-producing land cover reflecting wetland extent. We find that the Congo River has been discharging aged organic matter for several thousand years with apparently increasing ages from the Mid- to the Late Holocene. This suggests that aged organic matter in modern samples is concealed by radiocarbon from atmospheric nuclear weapons testing. By comparison to indicators for past rainfall changes we detect a systematic control of organic matter sequestration and release by continental hydrology mediating temporary carbon storage in wetlands. As aridification also leads to exposure and rapid remineralization of large amounts of previously stored labile organic matter we infer that this process may cause a profound direct climate feedback currently underestimated in carbon cycle assessments. This study was supported by the Deutsche Forschungsgemeinschaft (grants SCHN 621/3-3, RU 458/29-3, GR 1845/2-3, SCHE 903/1), the US National Science Foundation (grant OCE-0137005), a Starting Grant from the European Research Council (ERC) awarded to HMT for project AMOPROX (No. 258734) and grants ICM-NC120066 and FONDAP15110009 to RDP-H. This work was supported by the DFG Research Center/Cluster of Excellence ‘The Ocean in the Earth System’ at MARUM – Center for Marine Environmental Sciences, University of Bremen. 2017-02-15