ALBERT

Description: Abstract The Arctic Ocean mixed layer interacts with the ice cover above and warmer, nutrient rich waters below. Ice‐Tethered Profiler observations in the Canada Basin of the Arctic Ocean over 2006‐2017 are used to investigate changes in mixed layer properties. In contrast to decades of shoaling since at least the 1980's, the mixed layer deepened by 9 m from 2006‐2012 to 2013‐2017. Deepening resulted from an increase in mixed layer salinity that also weakened stratification at the base of the mixed layer. Vertical mixing alone can explain less than half of the observed change in mixed layer salinity, and so the observed increase in salinity is inferred to result from changes in freshwater accumulation via changes to ice‐ocean circulation or ice melt/growth and river runoff. Even though salinity increased, the shallowest density surfaces deepened by 5 m on average suggesting that Ekman pumping over this time period remained downwards. A deeper mixed layer with weaker stratification has implications for the accessibility of heat and nutrients stored in the upper halocline. The extent to which the mixed layer will continue to deepen appears to depend primarily on the complex set of processes influencing freshwater accumulation.

Description: Abstract Convective organization has a large impact on precipitation and feeds back on larger‐scale circulations in the tropics. The degree of this convective organization changes with modes of climate variability like the El Niño Southern Oscillation (ENSO), but because organization is not represented in current climate models, a quantitative assessment of these shifts has not been possible. Here, we construct multi‐decade satellite climatologies of occurrence of tropical convective organization and its properties and assess changes with ENSO phase. The occurrence of organized deep convection becomes more concentrated, increasing 3‐fold in the Eastern and Central Pacific during El Niño and decreasing 2‐fold outside of these regions. Both horizontal extent of the cold cloud shield and convective depth increase in regions of positive SSTa; however, the regions of greatest convective deepening are those of large‐scale ascent, rather than those of warmest SSTa. Extent decreases with SSTa at a rate of about 20 km K‐1, while the SSTa dependence of depth is only about 0.2 K K‐1. We introduce two values to describe convective changes with ENSO more succinctly: (1) an information entropy metric to quantify the clustering of convective system occurrences and (2) a growth metric to quantify deepening relative to spreading over the system lifetime. Finally, with collocated precipitation data, we see that rainfall attributable to convective organization jumps up to 5% with warming. Rain intensity and amount increase for a given system size during El Niño, but a given rain amount may actually fall with higher intensity during La Niña.

Description: Abstract The D/H ratio of epicuticular plant waxes (δDwax) preserved in sedimentary archives is a powerful tool for paleoclimate reconstruction, but comparisons to other proxy records or to climate model simulations requires a Proxy System Model (PSM) that accounts for transformations between δDprecip and δDwax. Here, we present a new, publicly available PSM for plant waxes, WaxPSM. WaxPSM predicts δDwax from observational data or any modern, paleo, or future climate model experiment. δD values of the C29 n‐alkane are calculated based on precipitation or soil water δD and observed apparent fractionation values, adjusted for plant‐type differences. Using WaxPSM, we assess three key uncertainties in δDwax records: the degree to which variations in δD may reflect changes in vegetation rather than climate; structural uncertainties that arise from limited water isotopic observations; and the impacts of land cover change on climate reconstructions during the Last Glacial Maximum and the Pre‐Industrial period. Parametric and structural uncertainties can cause δDwax variations up to 50‰, but in most cases the differences are ∼10‐30‰. The drier subtropics are additionally impacted by the incorrect structural assumption that plants' source water, δDsoil, is isotopically similar to the climate variable of interest, δDprecip. We recommend a coordinated, systematic effort to elevate observational constraints on δDprecip, δDsoil, and the δD of multiple compound classes, which would dramatically reduce parametric and structural uncertainties and allow further complexity to be built into the model.

Description: Abstract Questions Vegetation‐plot records provide information on presence and cover or abundance of plants co‐occurring in the same community. Vegetation‐plot data are spread across research groups, environmental agencies and biodiversity research centers and, thus, are rarely accessible at continental or global scales. Here we present the sPlot database, which collates vegetation plots worldwide to allow for the exploration of global patterns in taxonomic, functional and phylogenetic diversity at the plant community level. Location sPlot version 2.1 contains records from 1,121,244 vegetation plots, which comprise 23,586,216 records of plant species and their relative cover or abundance in plots collected between 1885 and 2015. Methods We complemented the information for each plot by retrieving climate and soil conditions and the biogeographic context (e.g. biomes) from external sources, and by calculating community‐weighted means and variances of traits using gap‐filled data from the global plant trait database TRY. Moreover, we created a phylogenetic tree for 50,167 out of the 54,519 species identified in the plots. Results We present the first maps of global patterns of community richness and community‐weighted means of key traits. Conclusions The availability of vegetation plot data in sPlot offers new avenues for vegetation analysis at the global scale. This article is protected by copyright. All rights reserved.

Description: Limnology and Oceanography Bulletin, Volume 28, Issue 1, Page 26-30, February 2019.

Description: Abstract Pacific Winter Water (PWW) enters the western Arctic Ocean from the Chukchi Sea; however, the physical mechanisms that regulate its circulation within the deep basin are still not clear. Here, we investigate the interannual variability of PWW with a comprehensive data set over a decade. We quantify the thickening and expansion of the PWW layer during 2002–2016, as well as its changing pathway. The total volume of PWW in the Beaufort Gyre (BG) region is estimated to have increased from 3.48 ± 0.04 × 1014 m3 during 2002–2006 to 4.11 ± 0.02 × 1014 m3 during 2011–2016, an increase of 18%. We find that the deepening rate of the lower bound of PWW is almost double that of its upper bound in the northern Canada Basin, a result of lateral flux convergence of PWW (via lateral advection of PWW from the Chukchi Borderland) in addition to the Ekman pumping. In particular, of the 70‐m deepening of PWW at its lower bound observed over 2003–2011 in the northwestern basin, 43% resulted from lateral flux convergence. We also find a redistribution of PWW in recent years toward the Chukchi Borderland associated with the wind‐driven spin‐up and westward shift of the BG. Finally, we hypothesize that a recently observed increase of lower halocline eddies in the BG might be explained by this redistribution, through a compression mechanism over the Chukchi Borderland.

Description: Abstract The Sustainable Development Goals (SDGs) emphasize the global and multi‐dimensional nature of sustainability and thus require improving our capacity to articulate and trace the impact of ecosystem change to measures of human well‐being. Yet, the integrated nature of these goals is challenging to assess without similarly integrated assessment tools. We present a new modeling toolkit, ‘Mapping Ecosystem Services to Human well‐being' (MESH), that integrates commonly used, stand alone ecosystem services models from the InVEST suite of models to quantify and illustrate the tradeoffs and synergies across five ecosystem services and up to ten associated SDGs. Development of the software and its functionality were informed by a broad stakeholder consultation with ministries, non‐governmental organizations and civil society groups in West Africa to identify common barriers to uptake and application of modeling tools in developing countries. In light of this process, key features included in MESH are 1) integration of multiple ecosystem service (ES) models into a common modeling framework supported by a curated base dataset; 2) built‐in scenario generation capacity to support policy analysis; 3) visualization of outcomes and tradeoffs, and 4) mapping of ecosystem service change to SDG targets and goals. We illustrate the use of MESH in a case study in the Volta basin of West Africa comparing the effectiveness of three alternative conservation prioritization approaches: (i) land cover‐based, (ii) topographic‐based and (iii) an ecosystem service‐based approach to minimize impact of agricultural expansion. We evaluate these approaches by linking changes in service supply to potential impacts on achievement of specific SDG goals and targets. This article is protected by copyright. All rights reserved.

Description: Abstract Aim Although species distribution models (SDMs) traditionally link species occurrences to free‐air temperature data at coarse spatio‐temporal resolution, the distribution of organisms might instead be driven by temperatures more proximal to their habitats. Several solutions are currently available, such as downscaled or interpolated coarse‐grained free‐air temperatures, satellite‐measured land surface temperatures (LST) or in‐situ‐measured soil temperatures. A comprehensive comparison of temperature data sources and their performance in SDMs is, however, currently lacking. Location Northern Scandinavia. Time period 1970–2017. Major taxa studied Higher plants. Methods We evaluated different sources of temperature data (WorldClim, CHELSA, MODIS, E‐OBS, topoclimate and soil temperature from miniature data loggers), differing in spatial resolution (from 1″ to 0.1°), measurement focus (free‐air, ground‐surface or soil temperature) and temporal extent (year‐long versus long‐term averages), and used them to fit SDMs for 50 plant species with different growth forms in a high‐latitudinal mountain region. Results Differences between these temperature data sources originating from measurement focus and temporal extent overshadow the effects of temporal climatic differences and spatio‐temporal resolution, with elevational lapse rates ranging from −0.6°C per 100 m for long‐term free‐air temperature data to −0.2°C per 100 m for in‐situ soil temperatures. Most importantly, we found that the performance of the temperature data in SDMs depended on the growth forms of species. The use of in‐situ soil temperatures improved the explanatory power of our SDMs (R2 on average +16%), especially for forbs and graminoids (R2 +24 and +21% on average, respectively) compared with the other data sources. Main conclusions We suggest that future studies using SDMs should use the temperature dataset that best reflects the ecology of the species, rather than automatically using coarse‐grained data from WorldClim or CHELSA.

Description: Abstract Life cycle assessment (LCA) analysts are increasingly being asked to conduct life cycle‐based systems level analysis at the earliest stages of technology development. While early assessments provide the greatest opportunity to influence design and ultimately environmental performance, it is the stage with the least available data, greatest uncertainty, and a paucity of analytic tools for addressing these challenges. While the fundamental approach to conducting an LCA of emerging technologies is akin to that of LCA of existing technologies, emerging technologies pose additional challenges. In this paper, we present a broad set of market and technology characteristics that typically influence an LCA of emerging technologies and identify questions that researchers must address to account for the most important aspects of the systems they are studying. The paper presents: (a) guidance to identify the specific technology characteristics and dynamic market context that are most relevant and unique to a particular study, (b) an overview of the challenges faced by early stage assessments that are unique because of these conditions, (c) questions that researchers should ask themselves for such a study to be conducted, and (d) illustrative examples from the transportation sector to demonstrate the factors to consider when conducting LCAs of emerging technologies. The paper is intended to be used as an organizing platform to synthesize existing methods, procedures and insights and guide researchers, analysts and technology developer to better recognize key study design elements and to manage expectations of study outcomes.

Description: Abstract To date Indian Summer Monsoon (ISM) dynamics have been assessed by changes in stalagmite δ18O. However, stalagmite δ18O is influenced by multiple environmental factors (e.g. atmospheric moisture transport, rainfall amount at the study site, ISM seasonality), precluding simple and clear reconstructions of rainfall amount or variability. This study aims to disentangle these environmental factors by combining δ18O, δ44Ca and elemental data from a stalagmite covering Termination II and the last interglacial from Mawmluh Cave, NE India, to produce a semi‐quantitative reconstruction of past ISM rainfall. We interpret δ18O as a mixed signal of rainfall source dynamics and rainfall amount, and coupled δ44Ca and X/Ca ratios as indicators of local infiltration rate and prior calcite precipitation in the karst zone. The wettest conditions in our studied interval (135 and 100 kyrs BP (BP = before present, with the present being 1950 CE)) occurred during MIS‐5e. Our multi‐proxy dataset suggests a likely change in seasonal distribution of MIS‐5e rainfall compared to the Holocene; the wet season was longer with higher‐than‐modern dry season rainfall. Using the last interglacial as an analogue for future anthropogenic warming, our data suggest a more erratic ISM behavior in a warmer world.