Deglaciations are periods in Earth’s geological history marked by the transition from glacial to interglacial climates. Recent research has increasingly focused on identifying similarities and differences among terminations, particularly the role of millennial-scale climate variability. These transitions are marked by episodes of a weakened Atlantic Meridional Overturning Circulation (AMOC), with widespread climate impacts. Observational data suggest that the AMOC may be weakening at present due to human-induced climate change, reinforcing the importance of terminations as case studies for understanding climate behavior under reduced AMOC, global warming, global ice loss, and monsoon changes. This study compares the evolution of Terminations V (ca. 430 ka), II (ca. 135 ka), and I (ca. 20 ka) from a paleoceanographic and paleoclimatic perspective based on marine sediment cores from the western tropical Atlantic. Sea surface temperature and salinity, bottom-water ventilation, and continental precipitation over the adjacent tropical South America will be reconstructed. For this purpose, we are conducting stable oxygen and carbon isotope analyses on planktonic and benthic foraminifera, Mg/Ca analyses on planktonic foraminifera, and X-ray fluorescence analyses on bulk sediment. Our goal is to identify specific patterns of climatic variability among these terminations, focusing on regional and global ocean-atmosphere responses. These results may improve our understanding of the dynamics of rapid climate transitions and their effects on the tropical Atlantic, as well as provide insights into potential present-day climate responses to AMOC weakening. Preliminary results will be presented. [FAPESP grants 2022/06452-0, 2024/11054-9, 2024/00949-5, 2025/19613-0 and 2025/05117-0].

Northeastern Brazil (NEB) is one of the most hydroclimatically sensitive regions in South America. Its globally semi-arid hydroclimate is shaped by the seasonal migration of the Intertropical Convergence Zone (ITCZ). Paleoclimate records documented a southward shift of the mean ITCZ position and intensified precipitation over NEB during millennial-scale events, which mobilized large quantities of detrital material transported to the adjacent Atlantic margin.Environmental magnetism offers a non-destructive, high-resolution approach to assess the sediment provenance, weathering intensity, and mineralogical transformations. Magnetic minerals such as magnetite, hematite, and goethite carry unique coercivity and thermal signatures that reflect their formation and transport history. Few paleoclimate studies showed an increase in high-coercivity minerals in NEB marine sediments during past millennial-scale events, which may reflect enhanced riverine input from intensely weathered continental regions. However, the interpretation of magnetic records is limited by the absence of modern reference datasets from upstream continental sources.Here we provide the first comprehensive rock-magnetic characterization of modern NEB continental sediments to better trace their provenance and improve the paleoclimatic interpretation of magnetic records in marine sediment cores. We investigated the magnetic mineralogy of about 80 modern sediment samples collected within the Parnaíba and the Maranhão hydrological systems using a suite of environmental magnetic techniques, which includes the acquisition and demagnetization of the Natural, Anhysteretic and Isothermal remanent magnetizations (NRM, ARM, IRM), stepwise thermal demagnetization of 3-axes IRM, hysteresis loops, backfield IRM curves with unmixing of coercivity spectra and thermomagnetic curves.First results highlight the diversity of modern magnetic signatures within the Parnaíba and the Maranhão basins. Different mixing proportions of low-coercivity minerals such as magnetite versus high-coercivity minerals such as hematite and goethite seem to reflect contrasting source conditions within NEB in terms of rainfall amount, weathering intensity and lithology. In addition, while samples dominated by magnetite are abundant in regions with a crystalline bedrock and in downstream areas close to river mouths, samples with a high proportion of high-coercivity minerals (hematite, goethite) dominate in upstream NEB regions. Therefore, a grain-size sorting process may also be at play along the Parnaíba and the Maranhão hydrological systems and contribute to explain the spatial differences in modern magnetic mineralogy observed within NEB.

The mid-Pleistocene transition (MPT, 1250 - 650 ka) marks the emergence of the 100-kyr-periodicity and more intense glacial cycles in the absence of significant change in orbital forcing, requiring a fundamental shift in Earth's internal climate system. A critical weakening of the glacial Atlantic deep circulation and an increased incursion of southern-sourced water masses at depth towards the North Atlantic between Marine Isotope Stages (MIS) 25 and 21 has been suggested as a key driver. This interval, known as “Atlantic Meridional Overturning Circulation (AMOC) crisis”, may have been responsible for enhancing carbon storage, reducing pCO2 and facilitating ice-sheet growth. However, the expression of the thermohaline disruption is not well-documented at mid-depths in the equatorial Atlantic, an important AMOC pathway. To investigate the variability of equatorial Atlantic mid-depth water masses, we used the stable carbon isotopic composition (δ13C) of benthic foraminifera from a composite of two sediment cores (MD23-3677Q and MD23-3678), collected at the same location in the western equatorial Atlantic at 1988 m water depth. We further calculated the vertical δ13C gradient with deeper sediment core ODP Site 925 (western equatorial Atlantic, 3052 m water depth). Our data suggest that the proposed incursion of Southern Ocean water masses during the “AMOC crisis” event did not affect depths shallower than 2000 m water depth in the equatorial Atlantic. Moreover, no substantial changes in water masses contribution were observed between the pre- and post-MPT intervals at mid-depths in this region.

The Trans-Amazon Drilling Project (TADP) is reconstructing the late Cenozoic history of Amazonian geology, climate, rivers, and forests. Drilling in the Acre Basin of western Brazil in 2023 recovered an 860 m drill core characterized by sediments that were deposited in a large paleo-river system. The overall sequence includes sandstones, siltstones, and mudstones that underwent varied degrees of weathering and pedogenesis. Here, we describe the ongoing geochronologic, geochemical, mineralogical, geophysical, and biotic analyses of the sedimentary record and present some preliminary inferences of the environmental history based on these initial results.Except for the uppermost similar to 12 m, sediments from the drill core represent a single lithostratigraphic unit, assigned to the Solim & otilde;es Formation, which is dominated by feldspar-rich sands of Andean origin. The pollen assemblage is quite different from Early to Middle Miocene floras that have been analyzed from a few sites elsewhere in the western Amazon. The novel pollen assemblage and new geochronological results suggest that the sequence may span the latest Miocene and all of the Pliocene Epoch, an interval that currently is not well represented in existing regional records and that is crucial for understanding the evolution of Amazonian biodiversity, as well as landscape transformations driven by Andean uplift and global climate change.

Understanding the temporal relationship between carbon pools in marine sediments is essential for reliable paleoenvironmental reconstructions, yet 14C-age discrepancies between organic and carbonate fractions remain poorly constrained. Here, we present the first assessment of the 14C-age offset between organic carbon (OC) and planktonic foraminifera from co-occurring stratigraphic layers of the Cabo Frio upwelling system (CFUS, off southeastern Brazil) over the past 5.8 kyr. Conventional 14C ages of the OC are, on average, 643 +/- 186 yr older than those of co-occurring foraminifera, likely reflecting long-term storage and winnowing of organic matter (OM) on the mid-shelf driven by local upwelling-related hydrodynamic processes. Higher OC apparent initial 14C-ages (AIROC) coincide with periods of intensified upwelling and stronger bottom currents, which prolong OC residence time before burial, and greater delivery of pre-aged terrestrial OM. Conversely, reduced AIROC corresponds to weaker hydrodynamic conditions and higher sedimentation rates that promote more rapid OC deposition. The new carbonate-based chronology developed for the investigated core revises the timing of Holocene paleoceanographic changes previously inferred from OC-based age models. Intensified South Atlantic Central Water (SACW) upwelling in the mid-shelf now aligns with the mid-Holocene sea-level highstand, while the development of stronger stratification and reduced SACW penetration occurs entirely within the late Holocene. The establishment of modern upwelling conditions shifted to younger ages, improving consistency with wider-scale climate phenomena and regional NE-wind variability. These results refine the temporal and mechanistic interpretation of Holocene variability in the CFUS and underscore the importance of multi-fraction 14C dating in dynamic coastal upwelling systems.

Southern-sourced intermediate waters play a central role in global ocean oxygenation and nutrient transport to low latitudes. However, the glacial-interglacial variability in their formation rate and geometry are not well constrained. Here we present a new ca. 787 thousand years-long benthic foraminifera stable carbon isotopic record from the Southeast Pacific, near the main formation region of Antarctic Intermediate Water (AAIW), which allows the investigation of changes in the formation rate and transport of AAIW over the last 787 kyr. Our results show glacial-interglacial changes in AAIW transport, with more AAIW being exported towards the Atlantic Ocean during interglacials, and to the low-latitude Pacific Ocean during glacials. We hypothesize that the AAIW exportation from the Pacific to the Atlantic Ocean is controlled by transport through the Drake Passage, which is reduced (increased) during glacial (interglacial) periods. The observed pattern is probably related to a combination of factors, including reduced (increased) sea-ice extent and southward (northward) shift of oceanic fronts and/or the westerlies during interglacials (glacials). Our mechanism reconciles the greater influence of AAIW in the northern Chilean margin during glacial periods, concurrent with the previously suggested decrease in formation rate and shallowing of this water mass. Ultimately, the glacial-interglacial variability in AAIW exportation to the Atlantic Ocean may be closely linked with changes in the stability of Atlantic Meridional Overturning Circulation during these distinct climate background states.

Northern northeastern Brazil (NEB) is a climate change hotspot due to its high biological and social vulnerability to ongoing and future hydroclimate changes. Precipitation in this region is influenced by the Intertropical Convergence Zone (ITCZ), which is largely controlled by the strength of the Atlantic Meridional Overturning Circulation (AMOC). Accordingly, the projected weakening of the AMOC due to anthropogenic global warming may substantially change NEB hydroclimate. Heinrich Stadials (HS), past millennial-scale events during which the AMOC was significantly weaker, provide important insights into the AMOC-ITCZ dynamics. This is especially true for those HS that occurred under similar to modern boundary conditions. HS10 (ca. 110 thousand years ago) was the first HS of Marine Isotope Stage 5, providing an ideal target for investigating AMOC-ITCZ dynamics under relatively warm climate conditions. Here we investigate the response of the surface and deep western equatorial Atlantic (WEA) circulation, as well as NEB precipitation to HS10. Therefore, we use foraminiferal carbon and oxygen stable isotopes and bulk sediment major elemental data from a marine sediment core retrieved from the WEA. Our results record a weakening of the AMOC during HS10 and show a concurrent increased WEA upper stratification and precipitation over NEB. We suggest that the mechanism controlling the WEA upper ocean stratification during HS depends on the background climate. Furthermore, we infer that the southward shift of the ITCZ during HS10 was more limited if compared to the shifts that occurred under colder climate background. Our findings provide useful insights into how a weakening of the AMOC under a relatively warm climate can impact the ITCZ and tropical South American precipitation.

Changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC) have been suggested to affect the mean latitude of the tropical rain-belt and the intensity of the South American Monsoon System. These changes impact Amazonian precipitation patterns, which play a critical role in sustaining the most biodiverse ecosystem on Earth. Consequently, the projected decrease in AMOC strength in response to anthropogenic climate change may constitute a serious risk to the stability of the Amazon rainforest. AMOC strength was significantly reduced during most millennial-scale stadials (e.g., Heinrich Stadials (HS)) of the last glacial and deglacial periods. These stadials offer valuable opportunities to understand the impact that slowdowns of the AMOC, as well as other concurrent changes of large-scale ocean and atmospheric conditions (e.g., sea ice extent, surface winds, ice sheet height and extent, sea level), had on Amazonian precipitation. Here we reconstruct precipitation changes that occurred in the Amazon Basin from 27.4 to 3.6 cal ka BP with a focus on Heinrich Stadial 1 (HS1, 18.6-14.6 cal ka BP) and the Younger Dryas (YD, 12.9-11.7 cal ka BP, also known as Heinrich stadial 0). To achieve this, two marine sediment cores collected from the slope of the western equatorial Atlantic were radiocarbon dated and analyzed for major elemental composition. To support the interpretation of our data, we employed (i) a comprehensive evaluation of major elemental composition in suspended sediments from the major rivers of the Amazon Basin, (ii) a regional compilation of tropical South American hydroclimate records, and (iii) outputs from a transient fully-coupled climate model run covering the last 21 ka. Our results reveal different precipitation patterns in the Amazon Basin during HS1 and the YD that were related to heterogenous displacements of the Intertropical Convergence Zone (ITCZ) and heterogenous sea surface temperature (SST) anomalies in the western equatorial Atlantic and the eastern equatorial Pacific. These changes were at least in part associated to different AMOC scenarios. Furthermore, two distinct phases are discernible within HS1 (i.e., HS1a from 18.6 to 16.6 cal ka BP and HS1b from 16.6 to 14.6 cal ka BP), each being characterized by variations in the relative concentrations of Al, K, Ca, Ti, and Fe. We interpret these sediment composition changes to be related to a shift in the main precipitation locus, that moved from the central Andes (HS1a) to southeastern Amazonia (HS1b). During HS1b, the low-pressure region over the eastern equatorial Pacific (due to a stronger positive SST anomaly in the eastern equatorial Pacific relative to the western equatorial Atlantic) produces, together with a shift further south in the ITCZ position, a positive precipitation anomaly over the southern and eastern Amazon Basin. Precipitation anomalies during the YD were apparently less conspicuous, located in the eastern Amazon Basin, but we cannot exclude the possibility of major elemental signals to be affected by a significant sea level rise that increased accommodation space for terrigenous sediments on the continental shelf. The heterogeneous response of precipitation under different AMOC scenarios reinforces the importance of hightemporal resolution paleoclimate studies from the Amazon Basin and the need to spatially compartmentalize the precipitation responses to these events due to the continental dimension of the basin.

Applications of quartz luminescence beyond sediment dating are expanding rapidly. A growing number of studies have successfully applied quartz optically stimulated luminescence (OSL) and thermoluminescence (TL) sensitivities in sediment provenance investigations and palaeoclimate reconstructions based on marine sediment cores, which are usually composed of fine-grained sediments (silt and clay), demanding measurements on polymineral samples. However, the procedures during sample preparation and the luminescence measurement conditions for determining the quartz OSL and TL sensitivities of fine-grained polymineral samples have not yet been extensively assessed. Here, we present the results of five different tests designed to determine whether the current procedures employed when preparing the samples and measuring their quartz luminescence sensitivities could be improved and/or simplified. The tests include assessing the dependency of quartz OSL and TL sensitivities on: (1) luminescence measurement conditions (i.e., with and without preheat, with light stimulation at room temperature and at 125 degrees C, based on natural and laboratory dose); (2) aliquot mass; (3) number of aliquots per sample; (4) grain size selection; and (5) feldspar content. Tests were performed on polymineral fine sediments from two marine cores, GeoB16206-1 and M78/1-235-1, recovered from the western equatorial Atlantic, close to the mouth of the Parnaiba and Orinoco rivers, respectively. In general, our results show that the procedures when preparing polymineral aliquots for quartz OSL or TL sensitivity measurements can be easily optimized on a case-by-case basis, saving time and resources. Our key result is that quartz OSL sensitivity obtained using natural signals and measured without thermal treatments (Test 1) are very similar to the results obtained using regenerative doses and preheating. This opens the possibility of reducing the OSL measurement time by 70 % and of scanning marine sediment cores with portable luminescence readers without the use of radiation sources for signal regeneration. Tests 2 and 3 show that both OSL and TL sensitivity results given by more than six aliquots or by aliquots made of 0.4 mg to 5 mg are indistinguishable. Waiting longer settling times to subsample finer fractions before mounting the aliquots (Test 4) is helpful to reduce feldspar, but it may also reduce the quartz significantly, limiting the %BOSL1s analysis. Finally, including an etching step to reduce feldspar (Test 5) is a helpful procedure to improve the TL and OSL sensitivity analysis, but not necessarily feasible for routine application with hundreds of samples.

The Great Acceleration is defined as a series of unprecedented, global human‐driven changes that occurred across socio‐economic and natural compartments of the Earth system after 1950. Among the observed changes, increase in fossil fuel burning has led to a significant accumulation of carbon dioxide (CO 2 ) in the atmosphere. By absorbing roughly 30% of total anthropogenic CO 2 emissions since the 1950s, the ocean is a major carbon sink, but the extent to which the natural oceanic carbon cycle was impacted by anthropogenic CO 2 is poorly known. To understand long‐term changes in the oceanic carbon cycle, coral reconstructions are important archives of past environmental variables. The stable carbon isotopic composition of corals (δ 13 C coral ) has been considered an important proxy for assessing changes in the isotopic composition of seawater dissolved inorganic carbon (δ 13 C DIC ), which ultimately reflects isotopic changes in atmospheric CO 2 (δ 13 C CO2 ). We use δ 13 C coral from the western tropical South Atlantic to assess changes in δ 13 C DIC to understand regional changes in the oceanic carbon cycle. The coral reconstruction documents significant carbon cycle changes across the pre‐to the post‐industrial transition, resulting in a δ 13 C coral decreasing trend of −0.0204‰ year −1 from 1928 to 2018, which intensified after the 1950s, during the Great Acceleration. Moreover, our δ 13 C coral reconstruction also shows decadal‐scale fluctuations not observed in atmospheric CO 2 . Our results suggest that the South Atlantic absorbed more anthropogenic CO 2 than previously thought and indicate an accelerated decline in δ 13 C DIC associated with changes in the ocean carbon cycle.

Linkages have been established between the Atlantic Multidecadal Oscillation (AMO) and surface air temperature variations, low-level jet streams, and precipitation trends in both northeastern Brazil and southeastern South America. Previous studies have discerned distinct wet-season (March-May) precipitation responses in northeastern Brazil, with cold (warm) AMO phases triggering increased (decreased) precipitation. Findings from various records indicate that the AMO's variability extends for thousands of years. A recent reconstruction suggests a significant AMO role in the shift from the Medieval Climate Anomaly (MCA) to the Little Ice Age (LIA) and reveals the LIA as the longest period with a persistent cold anomaly in the North Atlantic over the past similar to 3 millennia. Stable oxygen isotope records from South America show typical AMO periodicities (similar to 65 years), however, despite increased paleo precipitation data, the AMO's role in South American precipitation during the LIA and MCA remains unclear. In this study, the influence of AMO phases on atmospheric dynamics, precipitation patterns, and stable oxygen isotope composition (delta 18O) of precipitation over South America is assessed using the water isotope-enabled version of the Community Earth System Model version 1.2 (iCESM1.2). This research sheds light on the connection between AMO-induced precipitation anomalies and isotopic signals observed in paleoclimate records and emphasizes the significance of isotope-enabled climate models in unraveling the mechanisms behind past variations. The analysis involves comparing delta 18O simulations with published reconstructions from South America. By utilizing climate models that incorporate isotopes, we can delve deeper into understanding the impact of the AMO on precipitation patterns and isotopic ratios. Contrary to expectations, the simulated delta O-18(p) signal differ from speleothem records over the western Amazon and Andes during the LIA. That is, the simulated significant total precipitation amounts change over the western Amazon and Andes are not reflected in delta O-18(p) depletion.

Abstract By exchanging huge amounts of heat between the tropics and high latitudes, subtropical gyres significantly impact Earth's energy balance. Yet, their dynamical changes during the last deglaciation remain poorly understood. Here, nine records of the planktonic foraminiferal species Globorotalia truncatulinoides, that inhabits the permanent deep thermocline of subtropical gyres, are used to explore the meridional migration of both the North and South Atlantic subtropical gyres (NASG and SASG, respectively) in the past 22,000 years. We find that both gyres migrated poleward, with the SASG migration 1,500 years earlier than the NASG. Records from the North Atlantic Ocean indicate that the NASG's northern boundary has shifted over 6°. Climate model simulations suggest that these migrations are coupled with shifts in meridional temperature gradients. The poleward migration of the Atlantic subtropical gyres was crucial for sustaining a milder modern high‐latitude climate in comparison with that of the last ice age.

Climate models and paleo-reconstructions suggest that alterations in the Atlantic Meridional Overturning Circulation (AMOC) are not only indicators but also drivers of climate changes. Therefore, the AMOC is considered a critical tipping element within Earth’s climate system. Many lines of evidence indicate that the last glacial termination was characterised by large swings in AMOC strength, yet proxy evidence remains ambiguous about centennial-scale fluctuations during the Holocene. Inconsistencies persist regarding the timing, spatial pattern, and intensity of North Atlantic deep-water production. This study evaluates the variability of the AMOC during the Holocene based on several marine sediment cores covering the North Atlantic in high temporal resolution. For this, we exploit the 231Pa/230Th proxy, which indicates the bottom water advection strength. Additionally, past particle fluxes were reconstructed to determine a possible influence of particle composition and particle rain rate on the 231Pa/230Th signal. This study thus aims to extend existing paleo-circulation reconstructions of the AMOC from the last deglacial period with more recent analyses. Five new high-resolution 231Pa/230Th down-core records from different oceanographic settings and water depths in the North Atlantic consistently exhibit low variability throughout the entire Holocene. The 231Pa/230Th records generally display deviations of ± 10% from their respective Holocene mean. A generalised additive model (GAM) was fitted to the timeseries to detect mean North Atlantic trends within the different Holocene-normalised datasets. This model exhibits a virtually constant 231Pa/230Th level throughout the Holocene, interrupted by two time periods of slightly increased ratios, indicative of a weaker AMOC. The first time period is within the timeframe of the 8.2 ka event, characterised by a sudden cold spell across parts of the Northern Hemisphere. During this interval, four of the five timeseries show slightly elevated 231Pa/230Th ratios, although two records within this period hold a reduced sampling resolution. This limited temporal resolution and the shortness of the event make it challenging to decidedly conclude on the magnitude of the AMOC weakening during this time. The second period of higher 231Pa/230Th coincides with the 4.2 ka event and is only evident from the ODP 1063 data (Bermuda Rise). However, these higher 231Pa/230Th ratios can be explained by increased bottom scavenging of 231Pa presumably caused by benthic storms, induced by the transfer of eddy kinetic energy from the surface to the deep ocean. Consequently, atmospheric forcing during the 4.2 ka event seems to be a more plausible explanation than a paleoceanographic cause for the observed higher 231Pa/230Th. In conclusion, our study suggests that deep ocean circulation in the North Atlantic did not exhibit high variability on sub-millennial time scales, but has remained relatively stable throughout the Holocene.

Growing concerns surround the future of the Atlantic Meridional Overturning Circulation (AMOC) and its impacts on tropical regions, particularly due to changes in the dynamics of the Intertropical Convergence Zone (ITCZ). Northeastern Brazil, a tropical region strongly influenced by ITCZ dynamics, exhibits significant biological and social vulnerability to climate change, making it timely to understand how its hydroclimate could be impacted by AMOC changes in the face of anthropogenic global warming. The penultimate deglaciation was marked by a millennial-scale weak AMOC event called Heinrich stadial 11 (HS11; similar to 136-129 ka), providing an instructive target interval for improving our understanding of Northeastern Brazil hydroclimate responses to climate change. Here, we reconstruct paleoclimate changes during HS11 based on a multi-proxy approach applied to a high-resolution marine core from the western equatorial Atlantic. Our results suggest that HS11 was marked by a southward shift of the ITCZ, evidenced by paleoprecipitation records showing increased precipitation over Northeastern Brazil. These changes were concurrent with increased sea surface temperatures and reduced bottom water ventilation in the western equatorial Atlantic, interpreted as consequences of a weak AMOC. Importantly, we identified centennial-scale events within HS11, which are similar in nature but smaller in magnitude than HS11. These events align with North Atlantic climate changes, highlighting the crucial role that not only millennial- but also centennial-scale AMOC variability may play in low latitudes. Our findings raise concerns about the potential future impacts that an AMOC weakening may have on the hydroclimate of Northeastern Brazil and other tropical regions.

The Intertropical Convergence Zone (ITCZ) plays a central role in regulating tropical hydroclimate, with direct implications for water security and economic activity across vast regions. Changes in the latitudinal position of the ITCZ are strongly linked to interhemispheric surface temperature gradient, which is modulated by the Atlantic Meridional Overturning Circulation (AMOC). Past periods of AMOC weakening, such as Heinrich Stadials (HSs), offer valuable opportunities to investigate the ITCZ responses to high-latitude forcing. Here, we present a high-resolution multiproxy reconstruction of upper ocean stratification linked to ITCZ dynamics during HS 11 (ca. 136-129 ka), based on a marine sediment core retrieved from the western equatorial Atlantic (WEA; 1.03 degrees S). Beyond the southward-shift of the Atlantic ITCZ, our data reveal a two-phased structure within HS 11. Early HS 11 (ca. 136-134 ka) shows reduced upper ocean stratification, whereas late HS 11 (ca. 134-129 ka) exhibits enhanced stratification. Independent proxy records applied in this study suggest that these changes in stratification are primarily caused by variations in the upper ocean salinity gradient, with temperature playing a secondary role. Reduced stratification during early HS 11 reflects a stronger than previously recognized southward migration of the mean annual ITCZ, to a position south of our core site. During late HS 11, the ITCZ relaxed from this extreme southern position, enhancing upper ocean stratification at our core site. Our findings provide new insights into the southernmost position of the ITCZ during HSs and highlight the role of salinity in controlling upper ocean stratification in the WEA.

The region offshore Cape Blanc, NW Africa, is one of the most productive zones in the world’s oceans due to the occurrence of an eastern boundary upwelling system and dust input from the Sahara. It is also a well-known site for benthic foraminiferal research, where vertical zonation of the living foraminifera was first described in detail. However, earlier studies are based only on >150μm or >250μm specimens collected along one transect. Therefore, the relative proportion of the smaller, phytodetritus-related species (e.g., Alabaminella, Epistominella) is likely underestimated. This region was also the focus of foraminiferal stable carbon isotope (δ13C) studies.However, previous area works concentrated either on the sea surface or on the deep-water signals and their oceanographic meaning. Thus, there is a lack of data linking these two realms.Here we investigated foraminiferal assemblages, δ13C determinants, patterns, and shifts from the continental shelf to the abyssal plain. We analyzed ca. 360 samples from 12 multicore split in two parallel depth transects from ca. 100 to 3400 m water depth. The topmost 10 cm of each multicore was sampled in 1 cm intervals. We analyzed the δ13C composition of benthic species Cibicidoides wuellerstorfi (epifauna) and Uvigerina peregrina (infauna), as well as planktonic species Globigerinoides ruber white (>150 μm). Benthic and planktonic foraminiferal assemblages (>63 μm) were also determined.The δ13C difference between the sea-surface and the ocean-floor values (∆δ13CG. ruber white - C. wuellerstorfi) do not show notable changes along the two studied transects. However, the δ13C difference between the epifaunal and the infaunal species (∆δ13CC. wuellerstorfi - U. peregrina) shows a major increase from the continental shelf to the abyssal plain. Moreover, the benthic and planktonic foraminiferal assemblages present vertical and horizontal zonation related to the environmental parameters (e.g., oxygen, temperature, nutrients) and this is in accordance with the changes observed in geochemical signals showcasing a faunal and δ13C shift from the shore to the abyssal plain.Our findings argue for different determinants of δ13C off Cape Blanc. In the nearshore (ca.100-1500 m water depth) the main control is mineral-rich dust input from the Sahara, while below this depth and further away from the continental shelf lateral advection plays the dominant role.

Earth system models and paleo-reconstructions indicate that shifts in Atlantic Meridional Overturning Circulation (AMOC) strength profoundly impact global climate. While the last glacial termination experienced large AMOC variations, evidence of AMOC changes during the Holocene are poorly constrained. Here we present a Holocene AMOC reconstruction by quantifying mean bottom water advection strength in the deep North Atlantic. For this, we estimated volumetric flow rates from sedimentary 231Pa/230Th records with millennial resolution using the Bern3D model. We found that while during the Early Holocene the AMOC recovered from its weak deglacial state, it experienced a weakening between 9.2 to 8 ka BP, coinciding with North Atlantic meltwater pulses. From 6.5 ka BP onward, the AMOC strength stabilized, reaching its pre-industrial state around ~18 Sv. Hence, according to future projections, anthropogenic climate change may result in an AMOC slowdown unprecedented for most of the ongoing Holocene interglacial.

The Atlantic meridional overturning circulation (AMOC) and the Amazon forest are viewed as connected tipping elements in a warming climate system. If global warming exceeds a critical threshold, the AMOC may slow down substantially, changing atmospheric circulation and leading to Amazonia becoming drier in the north and wetter in the south. Yet, the impact of an AMOC slowdown on Amazon vegetation is still not well constrained. Here we use pollen and microcharcoal data from a marine sediment core to assess changes in Amazon vegetation from 25,000 to 12,500 years ago. Additionally, we model vegetation responses to an AMOC slowdown under both glacial and pre-industrial conditions. During a past AMOC slowdown (Heinrich Stadial 1-18,000 to 14,800 years ago), pollen data evidence a decline in cold- and moist-affinity elements, coupled with a rise in seasonal tropical vegetation. This pattern is consistent with the decline in suitability of northern Amazon moist forests in a model with an imposed 50% AMOC weakening under glacial conditions. Our modelling results suggest similar changes for a comparable AMOC slowdown under pre-industrial conditions. Combined with current disturbances such as deforestation and wildfires elsewhere in the basin, an AMOC slowdown may exert a systemic impact on the Amazon forest. A slower Atlantic meridional overturning circulation during Heinrich Stadial 1 led to the spread of seasonal tropical vegetation in northern Amazonia, a pattern that may repeat in a warming climate, according to proxy records combined with modelling.

Paleoclimate information has played an instrumental role in showing how fast climate can vary and how large these changes can be. It provided the first vivid demonstration of the relationships between atmospheric greenhouse gas concentrations and surface air temperatures, as well as striking representations of climate change impacts and possible feedbacks within the climate system, such as those associated with vegetation or ice sheet changes. Here, a short review of recent advances in paleoclimate studies is provided, with the objective of showing what this information on past climates and environments can bring to research on current and possible future climates. We advocate that (1) paleoclimatic and paleoenvironmental information can be leveraged for narratives about climate change, in particular at the local and regional levels, (2) paleoclimate data is essential for out-of-range tests of climate models, since future climates are also out of the range of recent climate information used for calibrating climate models, (3) paleoclimate data, in particular for the last millennia, is essential for taking multi-centennial and multi-millennial variability into account when describing trends related to anthropogenic forcings and attributing climate change signals, in particular for extreme and rare events, and (4) paleoclimates also provide extremely valuable information for initializing the slow components of climate models. In addition, we show how paleoclimate studies can be beneficial to put recent and future climate change into context and improve our knowledge on key processes. They can both benefit from and contribute to models and knowledge based on the study of recent and future climates.