Redefining Last Glacial Maximum environmental conditions in northeastern Brazil: pollen-based evidence of open and moist-adapted vegetation cover

Limited continuous continental records and complex climatic interactions hinder a comprehensive understanding of paleoclimatic and paleoenvironmental conditions during the Last Glacial Maximum (LGM) in the tropics. Adjacent to the currently semi-arid northeastern Brazil (NEB), a region strongly affected by the seasonal migration of the Intertropical Convergence Zone (ITCZ), marine sediment cores hold a valuable potential offering insights into past vegetation dynamics and continental hydroclimate. Here we present the first LGM pollen-based paleo-vegetation record with multicentennial-scale resolution from a marine core retrieved offshore NEB. Additionally, a top core dated to the 13 th century is presented as the closest available analogue to present-day conditions. Our LGM pollen data suggests grasslands and open vegetation physiognomies predominance and documents the presence of submontane taxa ( Podocarpus and Hedyosmum ), underscoring that NEB vegetation responded to global cooling trends. The occurrence and persistence of modern Cerrado and Caatinga arboreal taxa, along with gallery forest components and key indicators of wetland and warm environments ( Mauritia ), suggest a heterogeneous mosaic of ecological habitats in NEB, consistent with moderate tropical cooling of the lowlands (3 - 5°C). Although both the LGM and 13 th century intervals share a mixed Caatinga-Cerrado floristic signal, their contrasting assemblages reflect different temperature and hydroclimatic regimes, and further suggest the combined effects of the LGM reduced atmospheric CO 2 concentrations as key drivers of ecosystem structure. We suggest the LGM was characterized by higher effective moisture than under present-day conditions but with a different precipitation pattern, in response to a narrower amplitude of the ITCZ.