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Abstract The Southern Annular Mode (SAM) is the leading mode of atmospheric variability in the extratropical Southern Hemisphere and has wide ranging effects on ecosystems and societies. Despite the SAM’s importance, paleoclimate reconstructions disagree on its variability and trends over the Common Era, which may be linked to variability in SAM teleconnections and the influence of specific proxies. Here, we use data assimilation with a multi-model prior to reconstruct the SAM over the last 2000 years using temperature and drought-sensitive climate proxies. Our method does not assume a stationary relationship between the SAM and the proxy records and allows us to identify critical paleoclimate records and quantify reconstruction uncertainty through time. We find no evidence for a forced response in SAM variability prior to the 20th century. We do find the modern positive trend falls outside the 2 σ range of the prior 2000 years at multidecadal time scales, supporting the inference that the SAM’s positive trend over the last several decades is a response to anthropogenic climate change. 

This article describes the Research Apprenticeship Program (RAP), a mentored undergraduate research experience implemented in 2017 at a public land-grant institution located in the Appalachian region. The article focuses on RAP’s approach to recruiting, retaining, and supporting students in faculty-mentored research and creative inquiry. To assess the impact of RAP on undergraduate retention, institutional data were collected to identify RAP participants from the years 2017 to 2022 (n = 868) to compare next-year retention rates with institutional averages across similar demographic groups. The results showed that retention rates for RAP participants were significantly higher than institutional averages, and disaggregated data also showed higher retention rates for participants from historically marginalized populations. These This article describes the Research Apprenticeship Program (RAP), a mentored undergraduate research experience implemented in 2017 at a public land-grant institution located in the Appalachian region. The article focuses on RAP’s approach to recruiting, retaining, and supporting students in faculty-mentored research and creative inquiry. To assess the impact of RAP on undergraduate retention, institutional data were collected to identify RAP participants from the years 2017 to 2022 (n = 868) to compare next-year retention rates with institutional averages across similar demographic groups. The results showed that retention rates for RAP participants were significantly higher than institutional averages, and disaggregated data also showed higher retention rates for participants from historically marginalized populations. These results provide evidence of the program’s contribution to the educational development of the Appalachian region. 

Abstract Recent climate extremes in Mongolia have ignited a renewed interest in understanding past climate variability over centennial and longer time scales across north-central Asia. Tree-ring width records have been extensively studied in Mongolia as proxies for climate reconstruction, however, the climate and environmental signals of tree-ring stable isotopes from this region need to be further explored. Here, we evaluated a 182-year record of tree-ring δ13C and δ18O from Siberian Pine (Pinus sibirica Du Tour) from a xeric site in central Mongolia (Khorgo Lava) to elucidate the environmental factors modulating these parameters. First, we analyzed the climate sensitivity of tree-ring δ13C and δ18O at Khorgo Lava for comparison with ring-width records, which have been instrumental in reconstructing hydroclimate in central Mongolia over two millennia. We also compared stable isotope records of trees with partial cambial dieback (‘strip-bark morphology’), a feature of long-lived conifers growing on resource-limited sites, and trees with a full cambium (‘whole-bark morphology’), to assess the inferred leaf-level physiological behavior of these trees. We found that interannual variability in tree-ring δ13C and δ18O reflected summer hydroclimatic variability, and captured recent, extreme drought conditions, thereby complementing ring-width records. The tree-ring δ18O records also had a spring temperature signal and thus expanded the window of climate information recorded by these trees. Over longer time scales, strip-bark trees had an increasing trend in ring-widths, δ13C (and intrinsic water-use efficiency, iWUE) and δ18O, relative to whole-bark trees. Our results suggest that increases in iWUE at this site might be related to a combination of leaf-level physiological responses to increasing atmospheric CO2, recent drought, and stem morphological changes. Our study underscores the potential of stable isotopes for broadening our understanding of past climate in north-central Asia. However, further studies are needed to understand how stem morphological changes might impact stable isotopic trends.