ALBERT

Description: Record of Cariaco Basin near-surface [CO₃²⁻] from 1240-2007 C.E. derived from the area-density (shell weight (μg)/shell area (μm²)) of the planktonic foraminifer Globigerinoides ruber (pink). Area-density is used as a proxy for [CO₃²⁻] following the relationship presented in Marshall et al. (2013), using the two cores PL07-71-BC and CAR25-1

Description: Characterization of land cover change in the past is fundamental for understanding the evolution and present state of the earth system, the amount of carbon and nutrient stocks in terrestrial ecosystems, and the role played by land-atmosphere interactions in influencing climate. The estimation of land cover changes using palynology is a mature field, as thousands of sites in Europe have been investigated over the last century. Nonetheless, a quantitative land cover reconstruction at continental scale has been largely missing. Here we present a series of maps detailing the evolution of European forest cover during last 12000 years. Our reconstructions are based on the Modern Analogue Technique (MAT): a calibration dataset is built by coupling modern pollen samples with the corresponding satellite-based forest cover data. Fossil reconstructions are then performed by assigning to every fossil sample the average forest cover of its closest modern analogues. The occurrence of fossil pollen assemblages with no counterparts in modern vegetation represents a known limit of analogue-based methods. To lessen the influence of no-analogue situations, pollen taxa were converted into Plant Functional Types prior to running the MAT algorithm. We then interpolate site-specific reconstructions for each timeslice using a four-dimensional gridding procedure to create continuous gridded maps at continental scale. The performance of the MAT is compared against methodologically independent forest cover reconstructions produced using the REVEALS method; MAT and REVEALS estimates are most of the time in good agreement at a trend level, yet MAT regularly underestimates the occurrence of densely forested situations, requiring the application of a bias correction procedure The calibrated MAT-based maps draw a coherent picture of the establishment of forests in Europe in the early Holocene with the greatest forest cover fractions reconstructed between ~8500 and 6000 cal. yr. BP. This forest maximum is followed by a general decline in all parts of the continent, likely as a result of anthropogenic deforestation. The continuous spatial and temporal nature of our reconstruction, its continental coverage and gridded format make it suitable for climate, hydrological, and biogeochemical modelling, among other uses.

Description: Reconstructions of the vegetation of Europe during the Last Glacial Maximum (LGM) are an enigma. Pollen-based analyses have suggested that Europe was largely covered by steppe and tundra, and forests persisted only in small refugia. Climate-vegetation model simulations on the other hand have consistently suggested that broad areas of Europe would have been suitable for forest, even in the depths of the last glaciation. Here we reconcile models with data by demonstrating that the highly mobile groups of hunter-gatherers that inhabited Europe at the LGM could have substantially reduced forest cover through the ignition of wildfires. Similar to hunter-gatherers of the more recent past, Upper Paleolithic humans were masters of the use of fire, and preferred inhabiting semi-open landscapes to facilitate foraging, hunting and travel. Incorporating human agency into a dynamic vegetation-fire model and simulating forest cover shows that even small increases in wildfire frequency over natural background levels resulted in large changes in the forested area of Europe, in part because trees were already stressed by low atmospheric CO2 concentrations and the cold, dry, and highly variable climate. Our results suggest that the impact of humans on the glacial landscape of Europe may be one of the earliest large-scale anthropogenic modifications of the earth system.

Description: Dataset contains seawater and foraminiferal chemical composition from the paper referenced above. Paper abstract: Ba/Ca ratios in many non-spinose planktic foraminifera are markedly higher than those observed in spinose planktic species, but the cause for these high Ba/Ca ratios is not understood. A better understanding of this geochemical anomaly could provide insights into the habitat and/or controls over Ba incorporation in these species and expand their utility in paleoclimate research. In spinose species, shell Ba/Ca depends only on the Ba/Ca ratio of seawater. Proposed explanations for high non-spinose Ba/Ca include (1) the empirical partition coefficient, DBa, differs from the spinose species, (2) shell Ba varies with seawater temperature and pH, or (3) non-spinose foraminifers have a preference for prey that has elevated Ba. We performed laboratory culture experiments to determine DBa for the thermocline-dwelling non-spinose planktic foraminifer Neogloboquadrina dutertrei. We find that the Ba/Ca ratio of foraminiferal calcite secreted in the laboratory varies linearly with the Ba/Ca ratio of the seawater. The DBa for this species, 0.11 ± 0.008 (2SE; 95% CL), is similar to the DBa for spinose species (0.13 ± 0.004, 2SE; 95% CL). As in spinose species, the Ba/Ca ratio of cultured specimens of N. dutertrei is not influenced by culture temperature (12-22 °C) or seawater pHNBS (range 7.8-8.3). However, the Ba/Ca ratio of individual plankton-tow N. dutertrei specimens that completed their lifecycle in the ocean exceeds the Ba/Ca ratio of cultured specimens by up to three orders of magnitude. It is unlikely this difference between cultured specimens and ocean-grown specimens is due to seawater [Ba] variability, since seawater Ba/Ca ratios calculated using our DBa are much higher than exist in the ocean. Rather, we suggest that elevated shell Ba/Ca in plankton tow and fossil N. dutertrei is due to calcification in the microenvironment of marine organic aggregates such as marine snow, where [Ba] is elevated as a result of Ba release from biogenic particulates.

Description: This dataset is associated with Phelps et al. (2019) and is comprised of archaeological information from Holocene faunal assemblages in Africa, including assemblage, radiocarbon and taxonomic information. This dataset was modified from Jousse 2017 and associated datasets compiled by H. Jousse.

Description: Movies: for all mapped movies (movie S1 - S6): white circles indicate the presence of a pollen record; blue dots indicate archaeological remains of wild terrestrial ungulates; and red dots indicate the remains of domestic animals. The distribution of the faunal remains was based on summed probability distributions of radiocarbon dates at 100-year time intervals (see Phelps et al. in press for further methodological information). Movie S1a: The climatic envelope of forest mapped at 100-year intervals, using the direct methodology with WorldClim data (black background). Movie S1b: The climatic envelope of forest mapped at 100-year intervals, using the direct methodology with WorldClim data (white background). Movie S1c: The climatic envelope of forest mapped at 100-year intervals, using the direct methodology with TraCE-21ka climate information (black background). Movie S1d: The climatic envelope of forest taxa mapped at 100-year intervals, using the direct methodology with TraCE-21ka climate information (white background). Movie S1e: The climatic envelope of forest taxa mapped at 100-year intervals, using the indirect methodology, WorldClim data (black background). Movie S1f: The climatic envelope of forest taxa mapped at 100-year intervals, using the indirect methodology, WorldClim data (white background). Movie S1g: The climatic envelope of forest taxa mapped at 100-year intervals, using the indirect methodology, TraCE-21ka climate information (black background). Movie S1h: The climatic envelope of forest taxa mapped at 100-year intervals, using the indirect methodology, TraCE-21ka climate information (white background). ______________________________________________________________________________________ Movie S2a: The climatic envelope of grassy biomes (savanna- and steppe-associated taxa) mapped at 100-year intervals, using the direct methodology with WorldClim data (black background). Movie S2b: The climatic envelope of grassy biomes (savanna- and steppe-associated taxa) mapped at 100-year intervals, using the direct methodology with WorldClim data (white background). Movie S2c: The climatic envelope of grassy biomes (savanna- and steppe-associated taxa) mapped at 100-year intervals, using the direct methodology with TraCE-21ka climate information (black background). Movie S2d: The climatic envelope of grassy biomes (savanna- and steppe-associated taxa) mapped at 100-year intervals, using the direct methodology with TraCE-21ka climate information (white background). ______________________________________________________________________________________ Movie S3a: The climatic envelope of savanna-associated taxa mapped at 100-year intervals, using the indirect methodology, WorldClim data (black background). Movie S3b: The climatic envelope of savanna-associated taxa mapped at 100-year intervals, using the indirect methodology, WorldClim data (white background). Movie S3c: The climatic envelope of savanna-associated taxa mapped at 100-year intervals, using the indirect methodology, TraCE-21ka climate information (black background). Movie S3d: The climatic envelope of savanna-associated taxa mapped at 100-year intervals, using the indirect methodology, TraCE-21ka climate information (white background). ______________________________________________________________________________________ Movie S4a: The climatic envelope of steppe-associated taxa mapped at 100-year intervals, using the indirect methodology, WorldClim data (black background). Movie S4b: The climatic envelope of steppe-associated taxa mapped mapped at 100-year intervals, using the indirect methodology, WorldClim data (white background). Movie S4c: The climatic envelope of steppe-associated taxa mapped mapped at 100-year intervals, using the indirect methodology, TraCE-21ka climate information (black background). Movie S4d: The climatic envelope of steppe-associated taxa mapped mapped at 100-year intervals, using the indirect methodology, TraCE-21ka climate information (white background). ______________________________________________________________________________________ Movie S5a: The climatic envelope of desert-associated taxa mapped mapped at 100-year intervals, using the direct methodology with WorldClim data (black background). Movie S5b: The climatic envelope of desert-associated taxa mapped at 100-year intervals, using the direct methodology with WorldClim data (white background). Movie S5c: The climatic envelope of desert-associated taxa mapped at 100-year intervals, using the direct methodology with TraCE-21ka climate information (black background). Movie S5d: The climatic envelope of desert-associated taxa mapped at 100-year intervals, using the direct methodology with TraCE-21ka climate information (white background). Movie S5e: The climatic envelope of desert-associated taxa mapped at 100-year intervals, using the indirect methodology, WorldClim data (black background). Movie S5f: The climatic envelope of desert-associated taxa mapped at 100-year intervals, using the indirect methodology, WorldClim data (white background). Movie S5g: The climatic envelope of desert-associated taxa mapped at 100-year intervals, using the indirect methodology, TraCE-21ka climate information (black background). Movie S5h: The climatic envelope of desert-associated taxa mapped at 100-year intervals, using the indirect methodology, TraCE-21ka climate information (white background). ______________________________________________________________________________________ Movie S6a: The climatic envelope of xeric-associated taxa mapped at 100-year intervals, using the direct methodology with WorldClim data (black background). Movie S6b: The climatic envelope of xeric-associated taxa mapped at 100-year intervals, using the direct methodology with WorldClim data (white background). Movie S6c: The climatic envelope of xeric-associated taxa mapped at 100-year intervals, using the direct methodology with TraCE-21ka climate information (black background). Movie S6d: The climatic envelope of xeric-associated taxa mapped at 100-year intervals, using the direct methodology with TraCE-21ka climate information (white background). Movie S6e: The climatic envelope of xeric-associated taxa mapped at 100-year intervals, using the indirect methodology, WorldClim data (black background). Movie S6f: The climatic envelope of xeric-associated taxa mapped at 100-year intervals, using the indirect methodology, WorldClim data (white background). Movie S6g: The climatic envelope of xeric-associated taxa mapped at 100-year intervals, using the indirect methodology, TraCE-21ka climate information (black background). Movie S6h: The climatic envelope of xeric-associated taxa mapped at 100-year intervals, using the indirect methodology, TraCE-21ka climate information (white background). ______________________________________________________________________________________ Movie S7a: Multivariate environmental similarity surface (MESS) analyses plotted in geographic space using the direct methodology with repeated, modern-day WorldClim data. White areas demonstrate neutrality: i.e., neither similarity nor dissimilarity. Movie S7b: Multivariate environmental similarity surface (MESS) analyses plotted in geographic space using the direct methodology with TraCE-21ka climate information. White areas demonstrate neutrality: i.e., neither similarity nor dissimilarity. Movie S7c: Multivariate environmental similarity surface (MESS) analyses plotted in geographic space using the indirect methodology with repeated, modern-day WorldClim data. White areas demonstrate neutrality: i.e., neither similarity nor dissimilarity. Movie S7d: Multivariate environmental similarity surface (MESS) analyses plotted in geographic space using the indirect methodology with TraCE-21ka climate information. White areas demonstrate neutrality: i.e., neither similarity nor dissimilarity. ______________________________________________________________________________________ Movie S8a: Climatic envelope overlap between forest and grassy biomes (savanna and steppe) plotted in climate space. Envelopes were generated using the direct methodology and TraCE-21ka climate information. Red areas indicate the presence of grassy biomes only, whereas purple indicates overlap between grassy biomes and forest. For reference to the climatic variables used to define the climate space, see the TraCE-21ka correlation circle in figure A2. Movie S8b: Climatic envelope overlap between forest and savanna only, plotted in climate space. Envelopes were generated using the indirect methodology and TraCE-21ka climate information. Red areas indicate the presence of savanna only, whereas purple indicates overlap between savanna and forest. For reference to the climatic variables used, see the TraCE-21ka correlation circle in figure A2.