ALBERT

Description: Since net-zero greenhouse gas emissions targets have become a keystone of European and German climate policy, a debate about the need to actively remove carbon dioxide from the atmosphere in addition to drastically reducing emissions has emerged. Although still relatively scarce, empirical studies on the emergence of carbon dioxide removal (CDR) on the political agenda have shown that variations in the constellations and positions of policy-relevant actors play a key role in shaping patterns of CDR policymaking. The German and wider European Union (EU) CDR policy space is emergent, and political actors are just beginning to position themselves. Building on our previous work which established a typology of CDR policy integration patterns and developed a discourse analytical framework for mapping CDR-policy-relevant speaker positions, we present the first fine-grained empirical reconstruction of CDR-policy-relevant actors and their positions in the German context. Our analytical approach aims to improve understanding of patterns in CDR policymaking by showing that on the EU, national, and subnational levels, a multitude of institutional actors may adopt differing positions as the CDR policy space evolves. In addition to identifying fine-grained ‘ideal types’ of positions that policy actors may adopt in the formative phase of German CDR policy, our analysis provides an empirical ‘map’ of CDR policy-relevant actors and explores hypotheses about emerging discourse coalitions and potential conflict cleavages.

Description: Highlights • Climate engineering presents a novel challenge for global environmental governance • Institutional and discursive structures co-shape global environmental governance • A lack of joint analyses of both structures impedes understanding of governance emergence • A joint neo-institutionalist and post-structuralist analysis addresses this gap • Varying structures shape differing climate engineering governance decisions in several forums Abstract The Anthropocene is giving rise to novel challenges for global environmental governance. The barriers and opportunities shaping the ways in which some of these complex environmental challenges become governable on the global level are of increasing academic and practical relevance. In this article, we bring neo-institutionalist and post-structuralist perspectives together in an innovative framework to analyse how both institutional and discursive structures together bound and shape the global governance opportunities which become thinkable and practicable in the face of new global environmental challenges. We apply this framework to explore how governance of climate engineering – large scale, deliberate invention into the global climate system – is being shaped by discursive and institutional structures in three international forums: The London Convention and its Protocol, the Convention on Biological Diversity, and the United Nations Environment Assembly. We illustrate that the ‘degree of fit’ between discursive and institutional structures made climate engineering (un)governable in each of these forums. Furthermore, we find that the ‘type of fit’ set the discursive and institutional conditions of possibility for what type of governance emerged in each of these cases. Based on our findings, we critically discuss the implications for the future governance of climate engineering at the global level.

Description: Highlights • δ13C and δ18O profiles increase from exterior to interior until reaching a plateau. • Primary Layer δ13C reflects the δ13C of the Dissolved Inorganic Carbon. • In high pCO2 experiments, δ13C and δ18O closer to equilibrium fields. • Brachiopods grow according to an incremental growth model. Abstract Brachiopod shells are ubiquitous since the Early Cambrian up to now. As they secrete a shell made of low-magnesium calcite, more resistant to diagenesis than biocarbonates richer in Mg, their geochemical signatures are generally considered a powerful tool for paleo-environmental and paleo-climatic reconstructions. However, gaps in knowledge still remain on the underlying controls of the shell chemistry, in particular at a high spatial resolution. In this study, in situ oxygen and carbon isotope measurements by SIMS (Secondary Ion Mass Spectrometry) were performed in brachiopod shells of the cold-temperate water species Magellania venosa, constituted of a primary and a secondary layer. The individual specimens studied here grew under controlled conditions mimicking the natural environment and in experiments under low-pH (high pCO2) and high-temperature conditions. Transversal carbon and oxygen profiles showed a “brachiopod pattern” typical of extant two-layered brachiopods, with the primary layer depleted in 18O and 13C relative to equilibrium and the secondary layer showing a gradual increasing trend until reaching a near-equilibrium plateau. Overall, shells cultured at low pH were found to have δ18O and δ13C values closer to equilibrium when compared to shells from the control experiment. These near-equilibrium values may reflect a decrease in shell precipitation rate, leading to less kinetic effects, and/or a more rapid kinetics for the equilibration between DIC species and water. By close pairing of seawater δ18O and δ13C to that of shell microstructure, our study enables us to derive layer-specific C and O enrichment factors, which show the extent of pH and temperature effects superimposed on the seawater δ18O and DIC δ13C signal inherited. Finally, we show that during brachiopod shell growth, newly precipitated calcite is added to the calcite already existing, thus empirically validating the conceptual accretionary growth model proposed by Ackerly (1989).

Description: Highlights: • Huidobria chilensis is an endemic shrub distributed in the south of the Atacama Desert with a disjunct population at the northern coast. • Population and genetic structure correlate with geographic distance and geological factors. • Rain fall and fog, as well as ground water, must be regarded as important factors for populations at the coast and the Andean valleys, respectively. • A combination of different software tool to analyze GBS data allowed a good understanding of the population structure and genetic diversity. Abstract: Survival in hyperarid deserts is a major challenge for life in general and for plants in particular. The Atacama Desert presents harsh conditions such as limited rainfall, crusted soils, high soil salinity, high altitude, and intense solar radiation. These conditions, together with paleoclimatic variations over the last 10 million years, have influenced the genetic structure and connectivity of plant populations, resulting in a diverse flora with high endemism. However, the diversification of most lineages appears to be relatively recent, in contrast to the reported age of the Atacama Desert and the onset and expansion of hyperarid conditions since the late Oligocene and early Miocene. A prominent exception is Huidobria chilensis (Loasaceae), which is thought to be endemic to the Atacama since the Eocene. However, it is still not understood why this plant has been successful in adapting to the harshening environmental conditions. To investigate its genetic structure in relation to the history of the Atacama Desert, we studied 186 individuals from 11 populations using genotyping-by-sequencing (GBS). A total of nearly 56 k genome-wide single nucleotide polymorphisms (SNPs) were analyzed for population structure and genetic diversity. We identified four genetic clusters corresponding to geographic regions: the coastal region south of Tocopilla, the Cordillera de la Costa around Chañaral, and the Copiapó catchment 1 and 2. Genetic diversity within and between these clusters was analyzed along with rainfall, altitude, and landscape data. Although the genetic data support `isolation by distance’ as a major factor for genetic divergence between populations, the study also reveals the influence of topography on the distribution of H. chilensis and highlights the role of hydrologically connected watersheds and rivers in plant migration and colonization. This shapes the species' evolutionary trajectory and genetic diversity. Understanding these patterns in H chilensis lets one draw general conclusions about adaptation and survival strategies of plants in extreme desert environments such as the Atacama.

Description: Recent demands by developing countries, like India, that developed countries need to reach net-negative emissions, must be negotiated seriously under the UNFCCC. Failure to acknowledge that limiting global average temperature rise to 1.5°C leaves very little carbon budget for equitable redistribution risks further ambiguity on how to achieve the Paris Agreement’s goals.

Description: Highlights • Developed an innovative weighted outlier detection function that adaptively selects the best outlier detection technique, markedly improving precision and robustness in multibeam echosounder data analysis. • Demonstrated superior performance of the weighted function over traditional methods, achieving higher precision, recall, and F1 scores, pivotal for accurate seafloor mapping. • Enhanced data quality for geoscientific applications by effectively identifying and removing outliers without introducing data voids, preserving the integrity of multibeam sonar data. • The function’s significance extends to supporting sustainable environmental and resource management practices through improved accuracy in seabed mapping. • Discussed the adaptability of the method to various outlier patterns and its limitations, highlighting the need for further research and validation across different marine environments and data types. Abstract Multibeam sonar data are a valuable tool for seafloor mapping and geological studies. However, the presence of outliers in multibeam data can distort the results of analyses and reduce the accuracy of seafloor maps. In this paper, we define a weighting function based on the performance of various outlier detection techniques (OTDs) for detecting outliers in multibeam data, which calculates an outlier probability score for each sounding. Our results show that each OTD has its own strengths and weaknesses, and that a combination of outlier detection techniques is promising to improve reproducibility, explainability and the accuracy of the detection process. To address the challenge of detecting outliers in multibeam data, we propose a weighted outlier detection function that outperforms individual outlier detection techniques in terms of precision, recall and F1 scores by considering their strengths and combining them in a way that accounts for variations in the data. The function detects various types of outliers with high precision and recall values, resulting in valuable improvements in outlier detection performance for multibeam data. Overall, our proposed workflow has the potential to significantly improve the way multibeam data cleaning is performed, with the weighted outlier detection function being applied first, detecting most of the outlier automatically, followed by a domain-expert review of a small group of soundings whose automatic outlier labelling is not unequivocal.

Description: We explore a parameterization for mesoscale turbulence, closely related to that of Gent and McWilliams, in which forcing terms proportional to the isopycnal flux of potential vorticity appear in the averaged momentum equations. We show that in the presence of variable bottom topography, the parameterization predicts alongslope mean flow and a corresponding upslope bolus (eddy) flux of tracer that is associated with an alongslope-directed bottom eddy stress. The upslope bolus flux is in qualitative agreement with observations of a cold dome over seamounts. The predicted alongslope flow corresponds to flow fields found in geostrophic turbulence experiments and has some similarity (although conceptually very different, as discussed in the text) to Holloway's prediction based on statistical mechanics. By considering continuous stratification as a limiting case of a multilayer model, we show how to treat the surface and bottom boundaries. Practical application of the parameterization is illustrated using a three-dimensional -coordinate ocean circulation model that is very similar to the Bryan–Cox–Semtner model. The model-computed flow is consistent with observations of anticyclonic flow around a seamount. We show that the bottom eddy stress associated with the parameterization can be large, even compared to the annual mean surface wind stress, and hence could have important implications for the biology and water mass distribution of the coastal ocean as well as for the large-scale ocean circulation. From the climate modelling perspective, the approach adopted here provides a single formalism that combines the advantages of the Gent and McWilliams parameterization with alongslope mean flow similar to that suggested by Holloway.

Description: Highlights • Mercury methylation in sediment rapidly transported into water and diatoms. • CH3Hg flux was highest for sediments with higher sulfide and organic content. • Mineral and compressed sediment released minor Hg and CH3Hg. • Higher sediment Hg species flux does not correlate with high sediment content. • Stable isotope incubations provide substantial insight to environmental Hg cycling. Abstract Mercury (Hg) is a conspicuous and persistent global pollutant. Ionic Hg can be methylated into noxious methylmercury (CH3Hg), which biomagnifies in marine tropic webs and poses a health risk to humans and organisms. Sediment Hg methylation rates are variable, and the output flux of created CH3Hg are dependent on sediment characteristics and environmental factors. Thus, uncertainties remain about the formation and flux of CH3Hg from sediment, and how this could contribute to the bioaccumulative burden for coastal organisms in shallow ecosystems. Cores were collected from 3 estuarine locations along the Eastern USA to examine how sediments characteristics influence the introduction of Hg and CH3Hg into the base of the food chain. Stable isotopes of inorganic 200Hg and CH3199Hg were injected into sediments of individual cores, with cultured diatoms constrained to overlying waters. Five different treatments were done on duplicate cores, spiked with: (1) no Hg isotopes (control); (2) inorganic 200Hg; (3) CH3199Hg; (4) both 200Hg and CH3199Hg isotopes, (5) both 200Hg and CH3199Hg into overlying waters (not sediment). Experimental cores were incubated for 3 days under temperature and light controlled conditions. These results demonstrate that upper sediments characteristics lead to high variability in Hg cycling. Notably, sediments which contained abundant and peaty organic material (∼28 %LOI), had the highest pore water DOC (3206 μM) and displayed bands of sulfur reducing bacteria yielded the greatest methylation rate (1.97 % day−1) and subsequent diatom uptake of CH3200Hg (cell quota 0.18 amol/cell) in the overlying water.