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A 2,000 year-long oceanographic history, in sub-centennial resolution, from a Canadian Beaufort Sea continental shelf site (60meters water depth) near the Mackenzie River outlet is reconstructed from ostracode and foraminifera faunal assemblages, shell stable isotopes (delta 18O, delta 13C) and sediment biogenic silica. The chronology of three sediment cores making up the composite section was established using 137Cs and 210Pb dating for the most recent 150 years and combined with linear interpolation of radiocarbon dates from bivalve shells and foraminifera tests.Continuous centimeter-sampling of the multicore and high-resolution sampling of a gravity and piston core yielded a time-averaged faunal record of every approximately 40 years from 0 to 1850 CE and every approximately 24 years from 1850 to 2013 CE. Proxy records were consistent with temperature oscillations and related changes in organic carbon cycling associated with the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). Abundance changes in dominant microfossil species, such as the ostracode Paracyprideis pseudopunctillata and agglutinated foraminifers Spiroplectammina biformis and S. earlandi, are used as indicators of less saline, and possibly corrosive/turbid bottom conditions associated with the MCA (approximately 800 to 1200 CE) and the most recent approximately 60 years (1950–2013). During these periods, pronounced fluctuations in these species suggest that prolonged seasonal sea-ice melting, changes in riverine inputs and sediment dynamics affected the benthic environment. Taxa analyzed for stable oxygen isotope composition of carbonates show the lowest delta 18O values during intervals within the MCA and the highest during the late LIA, which is consistent with a 1 degree to 2 degree C cooling of bottom waters. Faunal and isotopic changes during the cooler LIA (1300 to 1850 CE) are most apparent at approximately 1500 to 1850 CE and are particularly pronounced during 1850 to approximately 1900 CE, with an approximate 0.5 per mil increase in delta 18O values of carbonates from median values in the analyzed taxa. This very cold 50-year period suggests that enhanced summer sea ice suppressed productivity,which is indicated by low sediment biogenic silica values and lower delta 13C values in analyzed species. From 1900CE to present, declines in calcareous faunal assemblages and changes in dominant species (Cassidulina reniforme and P. pseudopunctillata) are associated with less hospitable bottom waters, indicated by a peak in agglutinated foraminifera from 1950 to 1990 CE. 

Abstract Most of Earth’s rain falls in the tropics, often in highly seasonal monsoon rains, which are thought to be coupled to the inter-hemispheric migrations of the Inter-Tropical Convergence Zone in response to the seasonal cycle of insolation. Yet characterization of tropical rainfall behaviour in the geologic past is poor. Here we combine new and existing hydroclimate records from six large-scale tropical regions with fully independent model-based rainfall reconstructions across the last interval of sustained warmth and ensuing climate cooling between 130 to 70 thousand years ago (Marine Isotope Stage 5). Our data-model approach reveals large-scale heterogeneous rainfall patterns in response to changes in climate. We note pervasive dipole-like tropical precipitation patterns, as well as different loci of precipitation throughout Marine Isotope Stage 5 than recorded in the Holocene. These rainfall patterns cannot be solely attributed to meridional shifts in the Inter-Tropical Convergence Zone. 

Abstract. The Neogene and Quaternary are characterized by enormous changes in globalclimate and environments, including global cooling and the establishment ofnorthern high-latitude glaciers. These changes reshaped global ecosystems,including the emergence of tropical dry forests and savannahs that are foundin Africa today, which in turn may have influenced the evolution of humansand their ancestors. However, despite decades of research we lack long,continuous, well-resolved records of tropical climate, ecosystem changes,and surface processes necessary to understand their interactions andinfluences on evolutionary processes. Lake Tanganyika, Africa, contains themost continuous, long continental climate record from the mid-Miocene(∼10 Ma) to the present anywhere in the tropics and has longbeen recognized as a top-priority site for scientific drilling. The lake issurrounded by the Miombo woodlands, part of the largest dry tropical biomeon Earth. Lake Tanganyika also harbors incredibly diverse endemic biotaand an entirely unexplored deep microbial biosphere, and it provides textbookexamples of rift segmentation, fault behavior, and associated surfaceprocesses. To evaluate the interdisciplinary scientific opportunities thatan ICDP drilling program at Lake Tanganyika could offer, more than 70scientists representing 12 countries and a variety of scientificdisciplines met in Dar es Salaam, Tanzania, in June 2019. The teamdeveloped key research objectives in basin evolution, source-to-sinksedimentology, organismal evolution, geomicrobiology, paleoclimatology,paleolimnology, terrestrial paleoecology, paleoanthropology, andgeochronology to be addressed through scientific drilling on LakeTanganyika. They also identified drilling targets and strategies, logisticalchallenges, and education and capacity building programs to be carried outthrough the project. Participants concluded that a drilling program at LakeTanganyika would produce the first continuous Miocene–present record fromthe tropics, transforming our understanding of global environmental change,the environmental context of human origins in Africa, and providing adetailed window into the dynamics, tempo and mode of biologicaldiversification and adaptive radiations. 

Abstract The west Antarctic Peninsula (WAP) is a region of marked climatic variability, exhibiting strong changes in sea ice extent, retreat of most of its glaciers, and shifts in the amount and form of precipitation. These changes can have significant impacts on the oceanic freshwater budget and marine biogeochemical processes; it is thus important to ascertain the relative balance of the drivers and the spatial scales over which they operate. We present a novel 7‐year summer‐season (October to March; 2011 to 2018) series of oxygen isotopes in seawater (δ¹⁸O), augmented with some winter sampling, collected adjacent to Anvers Island at the WAP. These data are used to attribute oceanic freshwater changes to sea ice and meteoric sources, and to deduce information on the spatial scales over which the changes are driven. Sea ice melt shows significant seasonality (∼9% range) and marked interannual changes, with pronounced maxima in seasons 2013/14 and 2016/17. Both of these extrema are driven by anomalous winds, but reflect strongly contrasting dynamic and thermodynamic sea ice responses. Meteoric water also shows seasonality (∼7% range) with interannual variability reflecting changes in the input of accumulated precipitation and glacial melt to the ocean. Unlike sea ice melt, meteoric water extremes are especially pronounced in thin (<10 m) surface layers close to the proximate glacier, associated with enhanced ocean stratification. Isotopic tracers help to deconvolve the complex spatio‐temporal scales inherent in the coastal freshwater budget, and hence improve our knowledge of the separate and cumulative physical and ecological impacts.