ALBERT

Description: Weather causes extremes in photovoltaic and wind power production. Here we present a comprehensive climatology of anomalies in photovoltaic and wind power production associated with weather patterns in Europe considering the 2019 and potential 2050 installations, and hourly to ten-day events. To that end, we performed kilometer-scale numerical simulations of hourly power production for 23 years and paired the output with a weather classification which allows a detailed assessment of weather-driven spatio-temporal production anomalies. Our results highlight the dependency of low-power production events on the installed capacities and the event duration. South-shifted Westerlies (Anticyclonic South-Easterlies) are associated with the lowest hourly (ten-day) extremes for the 2050 (both) installations. Regional power production anomalies can differ from the ones in the European mean. Our findings suggest that weather patterns can serve as indicators for expected photovoltaic and wind power production anomalies and may be useful for early warnings in the energy sector.

Description: The southeastern tropical Atlantic hosts a coastal upwelling system characterized by high biological productivity. Three subregions can be distinguished based on differences in the physical climate: the tropical Angolan and the northern and southern Benguela upwelling systems (tAUS, nBUS, sBUS). The tAUS, which is remotely forced via equatorial and coastal trapped waves, can be characterized as a mixing-driven system, where the wind forcing plays only a secondary role. The nBUS and sBUS are both forced by alongshore winds and offshore cyclonic wind stress curl. While the nBUS is a permanent upwelling system, the sBUS is impacted by the seasonal cycle of alongshore winds. Interannual variability in the region is dominated by Benguela Niños and Niñas that are warm and cold events observed every few years in the tAUS and nBUS. Decadal and multidecadal variations are reported for sea surface temperature and salinity, stratification and subsurface oxygen. Future climate warming is likely associated with a southward shift of the South Atlantic wind system. While the mixing-driven tAUS will most likely be affected by warming and increasing stratification, the nBUS and sBUS will be mostly affected by wind changes with increasing winds in the sBUS and weakening winds in the northern nBUS.

Description: RV MARIA S. MERIAN MSM126 “Jellyweb Madeira” 9. Februar – 4. März 2024 1. Wochenbericht (9.-11. Februar, 2024)

Description: Ethiopia is highly vulnerable to climate change, the impacts of which can be felt across different sectors. In particular forests are threatened by rising temperatures, shifting precipitation patterns and extreme weather events. Human activities like deforestation and land-use change further exacerbate climate impacts, increasing the risk of wildfires and reducing the potential of forests for carbon sequestration. However, forests and trees are of major importance for ecosystems and local communities, providing plant and animal habitat, protection against soil erosion, provision of sufficient water resources, wood for fuel and construction, and various non-timber products. In addition, climate change is increasingly impacting water resources through prolonged and more frequent droughts, leading to water scarcity, crop failures and food insecurity for millions of people in Ethiopia. At the same time, erratic and heavy precipitation events lead to increased instances of flooding and soil erosion, further compromising water availability and quality. In a similar way, soils are impacted by climate change, with temperature increases and shifting precipitation patterns leading to soil degradation and reduced soil fertility, making it harder for smallholder farmers to pursue agriculture as a livelihood. Forests and trees are particularly threatened by climate change. At the same time, they are key in both climate change mitigation and adaptation efforts. Against this background, this policy brief discusses the potential of forests and trees in addressing climate change, specifically looking at natural forest regeneration as a mitigation strategy and at agroforestry as an adaptation strategy, highlighting the unique potential of forests and trees to achieve a dual benefit for climate action. Although these strategies are considered in greater detail, it should be noted that there is no single best mitigation or adaptation strategy, but rather different mutually complementing strategies. Mitigation describes efforts to reduce greenhouse gas emissions as well as measures to enhance greenhouse gas sinks. Forest and tree-based mitigation options can be classified as efforts to maintain the remaining forest cover (reduce deforestation and degradation), and measures to increase forest cover (natural regeneration and reforestation) (Nabuurs et al., 2007). We briefly describe each strategy but focus on natural regeneration later on.

Description: Agricultural sustainability faces challenges in the changing climate, particularly for rain-fed systems like those in Ethiopia. This study examines the combined impacts of climate change and soil acidity on future crop potential, focusing on Ethiopia as a case study. The EcoCrop crop suitability model was parameterized and run for four key food crops in Ethiopia (teff, maize, barley and common wheat), under current and mid-century climate conditions. To assess the impacts of soil acidification on crop suitability, a simulation study was conducted by lowering the soil pH values by 0.5, 1.0 and 1.5 and re-running the suitability model, comparing the changes in the area suitable for each crop. Our evaluation of the model, by comparing the modeled suitable areas with reference data, indicated that there was a good fit for all the four crops. Using default soil pH values, we project that there will be no significant changes in the suitability of maize, barley and wheat and an increase in the suitability of teff by the mid-century, as influenced by projected increases in rainfall in the country. Our results demonstrate a direct relationship between the lowering of soil pH and increasing losses in the area suitable for all crops, but especially for teff, barley and wheat. We conclude that soil acidification can have a strong impact on crop suitability in Ethiopia under climate change, and precautionary measures to avoid soil acidification should be a key element in the design of climate change adaptation strategies.

Description: The increasing global demand for seafood, coupled with the limitations of current fish stocks and aquaculture practices, requires the development of sustainable aquaculture solutions. In this context, this study explores the potential of a novel cage technology - Flow2Vortex - for the cultivation of jellyfish, a low-trophic-level organism with increasing market demand. The unique cage design creates a laminar and circular water flow, providing optimal conditions for cultivating fragile planktonic species. Indoor experiments demonstrated the successful growth of jellyfish in the cage, with growth rates of up to 11.6% per day. In addition, field tests in open waters confirmed the cage's ability to maintain a diffuse and controlled flow inside, even under strong external currents. The cage also maintained significantly higher zooplankton concentrations than the surrounding environment, offering a consistent food source for the cultivated jellyfish. These findings highlight the potential of the Flow2Vortex cage for scalable indoor and outdoor cultivation of low-trophic-level organisms, such as jellyfish, contributing to the diversification and sustainability of aquaculture practices.

Description: Die Energiewende sorgt für einen Paradigmenwechsel von einem grundlastbasierten zu einem flexiblen Stromsystem. Die zentralen Treiber für den zunehmenden Flexibilitätsbedarf sind die Stromerzeugung durch Wind und Sonne sowie die weiterhin bestehende unflexible Stromnachfrage, die gedeckt werden muss. Die vorliegende Studie analysiert, wie im Zeitverlauf bis zum Jahr 2045 der Flexibilitätsbedarf zunimmt und wie die Betriebsweisen der verschiedenen Technologien sich anpassen können. In der Studie wird auf das Energiesystemmodell REMod zurückgegriffen, mit dem eine Analyse über die intersektorale Flexibilität bis zum Jahr 2045 möglich ist. Für kurzfristige Flexibilität können in dieser Betrachtung zum Beispiel Batterien sowie Stromimporte und -exporte eingesetzt werden. Durch die Sektorenkopplung kann bei der Wärmebereitstellung in Gebäuden ebenfalls ein erheblich angepasstes Lastmanagement erfolgen. Ein höherer Anteil an Flexibilität kann jedoch durch Stromaufnahme in Elektrolyseanlagen und die Nutzung von Power-to-X-Kraftstoffen erfolgen. So können während längerer Dunkelflauten flexible Backup-Gasturbinen eingesetzt werden, um die Versorgungssicherheit zu gewährleisten. Um die notwendige Integration der Flexibilitäts-Technologien in den verschiedenen Märkten (insbesondere Strommarkt) und Sektoren voranzutreiben, müssen technische Voraussetzung, Marktregeln sowie Regulatorik in Bezug auf Bau und Betrieb so angepasst werden, dass die Technologien ihr Flexibilitätspotential bestmöglich ausspielen können.

Description: Mit steigendem Anteil fluktuierender Erneuerbarer Energien im Stromsystem steigt auch der Bedarf an steuerbaren Kapazitäten, die Stromangebot und -nachfrage ausgleichen können, so genannte Flexibilitätstechnologien. In dieser Analyse wird der Nutzen von zehn verschiedenen Technologien, die Flexibilität bereitstellen können, für das deutsche Stromsystem im Jahr 2030 ermittelt. Die Nutzenanalyse macht deutlich, dass die Verschiebung von großen Energiemengen über einen längeren Zeitraum (saisonaler Ausgleich) den höchsten spezifischen Nutzen erreicht. Eine Schlüsseltechnologie für das Jahr 2030 sind daher Langzeitspeicher mit großen Speichervolumen, zum Beispiel in Form von Wasserstoff-Kavernenspeichern. Das Fehlen einer hierfür geeigneten Technologie würde zu hohen Effizienzverlusten führen. Die zweite Schlüsseltechnologie ist die steuerbare Leistung von Power-to-Heat1 in Wärmenetzen der allgemeinen Versorgung, die für den täglichen Ausgleich zwischen Nachfrage und erneuerbarer Erzeugung eingesetzt wird. Hier können allerdings auch andere nachfrageseitige Flexibilitäten eine ähnliche Funktion für das Stromsystem übernehmen. Die Analyse zeigt auch, dass die Erschließung der hier betrachteten Flexibilitätstechnologien, zum Beispiel durch den Abbau von regulatorischen Hemmnissen, bis zum Jahr 2030 für das Stromsystem von hoher Relevanz ist. Auch über die angenommenen Potentialgrenzen hinaus bieten insbesondere nachfrageseitige Flexibilitätstechnologien noch einen positiven Nutzen. Eine technologieoffene, marktbasierte Lösung zur Einbindung dieser Flexibilitäten könnte die unterschiedlichen Charakteristika, Nutzenniveaus sowie sich ändernde Rahmenbedingungen effizient berücksichtigen.

Description: Catania (09.02.24) – Catania (22.02.24), MIDES - Measuring and Imaging Deformation of Etna’s Submerged unstable flank

Description: RV MARIA S. MERIAN MSM126 “Jellyweb Madeira” 9. Februar – 4. März 2024 2.Wochenbericht (12. – 18. Februar 2024)

Description: Highlights • More diverse non-native taxa generally include more economically costly species. • Chordates, nematodes and pathogens are among significantly over-represented taxa. • Monetary cost magnitude links positively to numbers of costly invasive species. • Costs are biased towards a few ‘hyper-costly’ invasive species groups. • Future invasion rates will continue to harbour new economically costly species. Abstract A dominant syndrome of the Anthropocene is the rapid worldwide spread of invasive species with devastating environmental and socio-economic impacts. However, the dynamics underlying the impacts of biological invasions remain contested. A hypothesis posits that the richness of impactful invasive species increases proportionally with the richness of non-native species more generally. A competing hypothesis suggests that certain species features disproportionately enhance the chances of non-native species becoming impactful, causing invasive species to arise disproportionately relative to the numbers of non-native species. We test whether invasive species with reported monetary costs reflect global numbers of established non-native species among phyla, classes, and families. Our results reveal that numbers of invasive species with economic costs largely reflect non-native species richness among taxa (i.e., in 96 % of families). However, a few costly taxa were over- and under-represented, and their composition differed among environments and regions. Chordates, nematodes, and pathogenic groups tended to be the most over-represented phyla with reported monetary costs, with mammals, insects, fungi, roundworms, and medically-important microorganisms being over-represented classes. Numbers of costly invasive species increased significantly with non-native richness per taxon, while monetary cost magnitudes at the family level were also significantly related to costly invasive species richness. Costs were biased towards a few ‘hyper-costly’ taxa (such as termites, mosquitoes, cats, weevils, rodents, ants, and asters). Ordination analysis revealed significant dissimilarity between non-native and costly invasive taxon assemblages. These results highlight taxonomic groups which harbour disproportionately high numbers of costly invasive species and monetary cost magnitudes. Collectively, our findings support prevention of arrival and containment of spread of non-native species as a whole through effective strategies for mitigation of the rapidly amplifying impacts of invasive species. Yet, the hyper- costly taxa identified here should receive greater focus from managers to reduce impacts of current invasive species.

Description: The coastal ocean contributes to regulating atmospheric greenhouse gas concentrations by taking up carbon dioxide (CO2) and releasing nitrous oxide (N2O) and methane (CH4). In this second phase of the Regional Carbon Cycle Assessment and Processes (RECCAP2), we quantify global coastal ocean fluxes of CO2, N2O and CH4 using an ensemble of global gap-filled observation-based products and ocean biogeochemical models. The global coastal ocean is a net sink of CO2 in both observational products and models, but the magnitude of the median net global coastal uptake is similar to 60% larger in models (-0.72 vs. -0.44 PgC year-1, 1998-2018, coastal ocean extending to 300 km offshore or 1,000 m isobath with area of 77 million km2). We attribute most of this model-product difference to the seasonality in sea surface CO2 partial pressure at mid- and high-latitudes, where models simulate stronger winter CO2 uptake. The coastal ocean CO2 sink has increased in the past decades but the available time-resolving observation-based products and models show large discrepancies in the magnitude of this increase. The global coastal ocean is a major source of N2O (+0.70 PgCO2-e year-1 in observational product and +0.54 PgCO2-e year-1 in model median) and CH4 (+0.21 PgCO2-e year-1 in observational product), which offsets a substantial proportion of the coastal CO2 uptake in the net radiative balance (30%-60% in CO2-equivalents), highlighting the importance of considering the three greenhouse gases when examining the influence of the coastal ocean on climate. The coastal ocean regulates greenhouse gases. It acts as a sink of carbon dioxide (CO2) but also releases nitrous oxide (N2O) and methane (CH4) into the atmosphere. This synthesis contributes to the second phase of the Regional Carbon Cycle Assessment and Processes (RECCAP2) and provides a comprehensive view of the coastal air-sea fluxes of these three greenhouse gases at the global scale. We use a multi-faceted approach combining gap-filled observation-based products and ocean biogeochemical models. We show that the global coastal ocean is a net sink of CO2 in both observational products and models, but the coastal uptake of CO2 is similar to 60% larger in models than in observation-based products due to model-product differences in seasonality. The coastal CO2 sink is strengthening but the magnitude of this strengthening is poorly constrained. We also find that the coastal emissions of N2O and CH4 counteract a substantial part of the effect of coastal CO2 uptake in the atmospheric radiative balance (by 30%-60% in CO2-equivalents), highlighting the need to consider these three gases together to understand the influence of the coastal ocean on climate. We synthesize air-sea fluxes of CO2, nitrous oxide and methane in the global coastal ocean using observation-based products and ocean models The coastal ocean CO2 sink is 60% larger in ocean models than in observation-based products due to systematic differences in seasonality Coastal nitrous oxide and methane emissions offset 30%-60% of the CO2 coastal uptake in the net radiative balance

Description: Shimmy dynamics of a dual-wheel nose landing gear system with torsional freeplay under stochastic lateral wind disturbances is studied. Dynamic characteristics of the deterministic case are numerically analysed, especially the shimmy of the landing gear through bifurcation analysis. Meanwhile, the influences of the freeplay nonlinearity on shimmy behaviours are examined in detail. We found that the freeplay leads to an enlargement of the shimmy area and an enhancement of the shimmy characteristics compared to the case without freeplay. Furthermore, impacts of stochastic lateral wind disturbances on the shimmy of the landing gear system are estimated via time history and recurrence plots. We find that the stochastic excitation enhances shimmy of the lateral bending direction. More interestingly, the stochastic excitation strengthens the effect of the freeplay nonlinearity, which causes random intermittent large-amplitude oscillations in the torsional direction. Our results show that the interaction between the freeplay nonlinearity and the random load induces a significant reduction in the critical shimmy velocity, which has an adverse impact on the stability of the nose landing gear of an aircraft. This work will provide an insightful guidance for the design of landing gear parameters in engineering practice.

Description: This is the data repository to reproduce the scenario analysis of the paper "Complementary roles of direct and indirect electrification in pathways to a renewables-dominated European energy system".

Description: A new resilient distributed secondary control for AC microgrids is studied based on event-triggered mechanisms and trust-reputation evaluation methods. When distributed generators (DGs) in a microgrid are subject to attacks, their transmitted state information would be tampered and thus affect the dynamics of normal generators. In order to isolate possible attacks, two types of trust evaluation metrics with different attack indices and time scales are designed, by which the performance of neighboring DGs can be assessed for specific practical demands. Based on the trust values of each neighbor, a reputation-propagation method is introduced at triggered time instants to determine whether a DG is under attack by comprehensively incorporating the opinion of mutual neighbors. The dynamic updating law of the communication edge weights is utilized with the derived reputation values. Based on this, a distributed Zeno-free event-triggered control protocols for voltage/frequency restoration and active power sharing are proposed. Sufficient conditions for picking proper control parameters are given in the main theorem. Lastly, the simulations are conducted in MATLAB/SimPowerSystems for several scenarios to validate the effectiveness of the proposed algorithms.

Description: This paper analyses poverty dynamics and checks for the existence of poverty traps among refugee and host communities living close to each other in Uganda. Although some non-linearities emerge in asset dynamics, there is convergence towards one stable equilibrium for the whole sample that suggests the existence of a structural poverty trap. However, households are quite heterogeneous: when analysing refugees and hosts separately, refugees converge to a lower own-group equilibrium than hosts. The household size and education are asset growth enablers for both communities. Noticeably, access to land, past history and social cohesion are also significant correlates of refugees’ asset dynamics. From a policy perspective, structural poverty traps are bad news, because standard anti-poverty interventions would not unlock the trap. Our results stress the need of more structural approaches aimed at promoting economic growth in the whole area where refugee and host communities live, targeting both communities.

Description: Die schnelle und umfassende Emissionsminderung in der Energie- und Kreislaufwirtschaft ist der Schlüssel für die Begrenzung der Erderwärmung auf unter 2 °C. In Deutschland werden entsprechende Politiken seit den 1990er-Jahren verfolgt, allerdings erst in jüngster Vergangenheit mit dem notwendigen Nachdruck und der notwendigen Orientierung hin zu mehr Marktmechanismen. Wesentliche Handlungsfelder sind Energieeinsparung und erhöhte Energieeffizienz, Umstieg auf erneuerbare Energien, Bepreisung von Klimagasen sowie eine Reduzierung und Schließung der Stoffkreisläufe. In allen Handlungsfeldern sind Grundlagen geschaffen, es bleibt jedoch der Großteil des Weges noch zu gehen, um Klimaneutralität zu erreichen. Für einen schnellen Fortschritt spielen neben der Überwindung der technischen, ökonomischen und organisatorischen Herausforderungen auch Verteilungsfragen und die Einbettung in internationale Maßnahmen eine zunehmende Rolle.

Description: Recent research on environmental inequality has extended its focus from ongoing pollution to legacy pollution by examining the geography of industrial brownfields, defined as non-productive, contaminated land. This article is the first extensive brownfield analysis for a European country from an environmental inequality perspective, exploiting the political momentum in France where brownfield restoration has become a national priority. We combine data on over 7200 industrial brownfields from the 2022 geodatabase ‘Cartofriches’ with socio-economic variables at the municipality level. We demonstrate that communities with higher percentages of foreign-born and unemployed persons are disproportionately more likely to be located in proximity to brownfields. The social gradient increases significantly in communities that host more than two brownfields. There is an inverted U-shaped relationship with income, with a turning point at approximately 25,600 annually. These findings are robust across urban and rural areas, though with regional differences. Our analysis provides entry points for restorative environmental justice considerations and has important implications for Europe's just transition and cohesion policies.

Description: Precipitation is essential for food production in Sub-Saharan Africa, where more than 80 % of agriculture is rainfed. Although ∼40 % of precipitation in certain regions is recycled moisture from Africa's tropical rainforest, there needs to be more knowledge about how this moisture supports the continent's agriculture. In this study, we quantify all moisture sources for agrarian precipitation (African agricultural precipitationshed), the estimates of African rainforest's moisture contribution to agricultural precipitation, and the evaporation from agricultural land across the continent. Applying a moisture tracking model (UTRACK) and a dynamic global vegetation model (LPJmL), we find that the Congo rainforest (〉60 % tree cover) is a crucial moisture source for many agricultural regions. Although most of the rainforest acreage is in the DRC, many neighboring nations rely significantly on rainforest moisture for their rainfed agriculture, and even in remote places, rainforest moisture accounts for ∼10–20 % of agricultural water use. Given continuous deforestation and climate change, which impact rainforest areas and resilience, more robust governance for conserving the Congo rainforest is necessary to ensure future food production across multiple Sub-Saharan African countries.

Description: Renewable electricity can facilitate climate change mitigation in the buildings, industry and transport sector via direct electrification or indirect electrification, that is, converting electricity to hydrogen-based fuels. While direct electrification is generally energy efficient, indirect electrification can partially build upon existing applications and infrastructure. However, their roles and relative importance have not been well researched in mitigation scenarios. Here, we derive plausible ranges for both strategies based on EU climate neutrality scenarios using the REMIND model. We find that by 2050 direct electrification is the dominant strategy with an electricity share of 42%–60% in final energy, while indirect electrification is necessary in hard-to-electrify sectors and contributes a share of 9%–26%. Our analysis highlights that policy makers should respect the distinct sectoral roles of both strategies by fostering an end-use transformation towards direct electrification while prioritizing hydrogen and synthetic fuels for applications where they are indispensable.

Description: Highlights: • Ca. 418 ka Pauzhetka tephra from South Kamchatka was found in 11 marine sediment cores. • New major and trace element analyses allow identification of tephra glasses. • K/Ti and K/Fe maxima mark the Pauzhetka tephra presence in marine sediments. • The tephra occurs at Marine Isotope Stages 12 to 11c and below the Bermuda excursion. • The revised ash dispersal covers vast areas in the NW Pacific and Okhotsk Sea. Abstract: The distal Pauzhetka tephra, formed by a large caldera-forming volcanic eruption in South Kamchatka, has been identified in eleven recently recovered marine sediment cores based on major and trace element compositions of tephra glass. Ten SO264 cores form a transect along the Emperor Seamount Chain (ESC) in the Northwest (NW) Pacific between ∼50.3° and ∼45°N, 800–1200 km southeast of the Pauzhetka caldera. One additional core LV28-41-4 was retrieved in the Okhotsk Sea, ∼600 km west of the caldera. The Pauzhetka tephra glass shards have a characteristic medium-K rhyolite composition and trace element content compatible with the rear-arc position of the source volcano that ensures their identification. In the NW Pacific SO264 cores, the tephra is preserved as layers in cores 33, 47, 49, 53, 55, 56 and 62, as a lens in core 45, and as cryptotephra in cores 57 and 66. It forms a cryptotephra in the Okhotsk Sea core LV28-41-4. Distinctively high XRF-retrieved K/Ti and K/Fe ratios compared to those for the host sediments help identify the Pauzhetka tephra. According to our refined stable oxygen isotope (δ18O)- and magneto-stratigraphy of two studied and two reference cores, the Pauzhetka tephra occurs within a local δ18O maximum during a transition from marine isotope stage 12 to 11c (Termination V) and below a paleointensity minimum referred to as the Bermuda excursion, at ca. 418 ka. Using the tephra age as an isochron, we show that average linear sedimentation rates decrease southward along a transect of the SO264 cores, except in core 55. It partially reflects an intensification of mid-depth currents causing winnowing, erosion or non-deposition along the ESC over the past 418 kyr. An increased linear sedimentation rate in core 55, recovered from the southern leeward side of the Minnetonka Seamount, appears to record the pelagic accumulation protected from the mid-depth current influence. Our findings expand the former ash dispersal area farther southeast in the NW Pacific and southwest in the Okhotsk Sea. The new data on the tephra thickness supports the axis direction of the fallout zone southeast of the Pauzhetka caldera. Our results suggest the Pauzhetka tephra as a key middle Pleistocene isochron for the stratigraphy and correlation of the NW Pacific and Okhotsk Sea sediments.

Description: Three boreholes drilled during the International Ocean Discovery Program (IODP) Expedition 396 have yielded unexpected findings of altered granitic rocks covered by basalt flows, interbedded sediments and glacial mud near the continent‐ocean transition of the mid‐Norwegian margin. U‐Pb and K‐Ar geochronological analyses were conducted on both protolithic and authigenically formed K‐bearing minerals to determine the age of granite crystallisation and subsequent alteration episodes. The granite's crystallisation age based on 104 zircons is 56.3 ± 0.2 Ma, and subsequent exhumation along with alteration/weathering events took place between 54.7 ± 1 and 37.1 ± 1 Ma. This intrusion represents the youngest granite discovered in Norway and intruded at an extremely shallow crustal level before a rapid rift‐to‐drift transition. The shallow emplacement of granitic rock and its fast exhumation before and during the onset of volcanism holds significant implications for the syn‐ and post‐breakup tectonic evolution of volcanic margins.

Description: Predatory non-indigenous species (NIS) have profound impacts on global ecosystems, potentially leading to native prey extinction and reshaping community dynamics. Among mechanisms potentially mediating predator impacts and prey invasion success are predator preferences between native vs. non-indigenous prey, a topic still underexplored. Using functional response and prey preference experiments, this study focused on the predation by the non-indigenous Japanese brush-clawed shore crab, Hemigrapsus takanoi, between the native gammarid Gammarus duebeni and the analogous non-indigenous Gammarus tigrinus. Although H. takanoi showed subtle differences in its functional response type between the two prey species, its preferences across their environmental frequencies were not strongly influenced by the prey invasion scenario. The findings highlight the need for a comprehensive understanding of interactions in ecosystems with multiple NIS, offering fresh insights into complex feeding interactions within marine environments.

Description: The past ∼200 million years of Earth's geomagnetic field behavior have been recorded within oceanic basalts, many of which are only accessible via scientific ocean drilling. Obtaining the best possible paleomagnetic measurements from such valuable samples requires an a priori understanding of their magnetic mineralogies when choosing the most appropriate protocol for stepwise demagnetization experiments (either alternating field or thermal). Here, we present a quick, and non‐destructive method that utilizes the amplitude‐dependence of magnetic susceptibility to screen submarine basalts prior to choosing a demagnetization protocol, whenever conducting a pilot study or other detailed rock‐magnetic characterization is not possible. We demonstrate this method using samples acquired during International Ocean Discovery Program Expedition 391. Our approach is rooted in the observation that amplitude‐dependent magnetic susceptibility is observed in basalt samples whose dominant magnetic carrier is multidomain titanomagnetite (∼TM 60–65 , (Ti 0.60–0.65 Fe 0.35–0.40 )Fe 2 O 4 ). Samples with low Ti contents within titanomagnetite or samples that have experienced a high degree of oxidative weathering do not display appreciable amplitude dependence. Due to their low Curie temperatures, basalts that possess amplitude‐dependence should ideally be demagnetized either using alternating fields or via finely‐spaced thermal demagnetization heating steps below 300°C. Our screening method can enhance the success rate of paleomagnetic studies of oceanic basalt samples. Plain Language Summary Oceanic basalts are ideal recorders of the Earth's magnetic field. To decipher magnetic histories recorded in rocks, paleomagnetists need to isolate the magnetization directions and intensities within rocks by one of two possible methods. One method typically involves progressively heating the samples to high temperatures. The other method involves exposing samples to alternating magnetic fields with increasing peak field intensities. Both of these methods are ultimately destructive to the original magnetization preserved within rocks. However, without knowledge of a given rock's magnetic mineralogy, randomly choosing thermal or alternating field demagnetization methods may result in high failure rates. We developed a pre‐screening method to help decide which cleaning method will likely be more successful for a given sample based on low‐field magnetic susceptibility measurements. These measurements do not affect the original magnetic information recorded in a rock, thereby permitting subsequent paleomagnetic studies on the same sample. Our technique can be performed as rapidly as 2 min per sample, is non‐destructive, and does not require complicated sample preparation. Key Points Paleomagnetic studies utilize either alternating field or thermal demagnetization, but it is difficult to choose the best protocol a priori Amplitude‐dependence of magnetic susceptibility measurements permits preliminary magnetic mineralogy characterization in submarine basalts Rapid amplitude‐dependence measurements may aid in deciding upon the best demagnetization protocol for submarine basalt samples

Description: Marginal seas influenced by large rivers are characterized by complex hydrodynamic and organic matter cycling processes. However, the impacts of hydrodynamics on the composition and reactivity of particulate organic matter (POM) remain unclear. Here we conducted a comprehensive study on the bulk, molecular and biological properties of suspended POM in the Changjiang Estuary and adjacent area subjected to strong currents, eddies as well as typhoons during spring and autumn. D/L‐enantiomers of particulate amino acids (PAA) were analyzed to evaluate the bioreactivity of POM and quantify bacterial‐derived organic carbon. We found that POM bioavailability as indicated by carbon‐normalized yields of PAA (PAA‐C%) reflected the ecosystem productivity. Relatively high PAA‐C% values (20−35%) were observed in productive areas influenced by Changjiang River plume, cyclonic eddies and typhoons, likely related to the enhanced nutrient availability arising from hydrodynamic processes. In contrast, the oligotrophic Taiwan Warm Current‐influenced regions featured relatively low POM bioavailability (PAA‐C% 〈 10%) despite typhoons facilitating water mixing. The PAA‐C% values showed a significant positive correlation with extracellular enzyme activity, indicating that bioavailable POM can rapidly stimulate heterotrophic transformation. Hot spots of elevated bioavailable POM showed high contributions of bacterial organic carbon. A large portion (∼2/3) of bacterial organic carbon was present in the form of bacterial detritus, suggesting that patches of these biological hot spots represent important sites of carbon sequestration. Together, our findings indicate that fresh POM production is largely controlled by nutrient supply driven by hydrodynamic processes, with important implications for carbon sequestration in the dynamic ocean margins. Plain Language Summary Marginal seas are subject to complex hydrodynamic processes and play an important role in carbon sequestration. Disentangling the linkages between hydrodynamics and organic carbon reactivity and composition is crucial to understanding the regional carbon cycle. Here we collected suspended particulate organic matter (POM) in the Changjiang Estuary and adjacent coastal areas. Based on the biomarker D/L‐amino acids, we assessed the bioavailability of POM and quantified the organic carbon originating from bacteria. We found that high bioactivity of POM occurred in productive Changjiang River plume, cyclonic eddy, and typhoon influenced areas. These hydrodynamic processes appear to increase nutrient availability, therefore promoting phytoplankton growth. Bioavailable POM can rapidly stimulate heterotrophic activity and facilitate the transformation of algal‐derived organic carbon to bacterial detritus, thus contributing to carbon sequestration. Our findings suggest that the production of bioavailable POM is largely controlled by hydrodynamically driven nutrient supply. Key Points We use D/L‐amino acids to assess the bioreactivity and bacterial origins of particulate organic matter (POM) in the dynamic Changjiang Estuary and adjacent area High bioavailability of POM occurs in productive regions affected by Changjiang River plume, cyclonic eddies and typhoons Hot spots of bioavailable POM represent important sites for carbon sequestration

Description: Octocorals (Cnidaria: Anthozoa) have a global distribution and form benthic assemblages along the depth gradient, from shallow to deep waters. They often occur below SCUBA diving limits, where they can become dominant habitat builders and aggregate different taxa. During a cruise in February 2023, one octocoral specimen was collected at 1453 m depth at Kebrit Deep, in the northern Saudi Arabian Red Sea axis, an area with extremely high temperature and salinity profiles at depth. Morphological analysis coupled with DNA barcoding using two mitochondrial markers ( COI and mtMuts ), revealed that the coral belongs to Acanthogorgia , a genus of azooxanthellate octocorals known to occur from 3 to 2300 m depths in cold, temperate and tropical waters. In the Red Sea, the genus was previously only known from shallower waters. Hence, we report the deepest record of the genus Acanthogorgia from the warm and saline Red Sea basin. This finding provides novel insights on deep-water octocoral diversity in the Red Sea, a still scantily explored area of the world, while emphasizing the need for further explorations at depth.

Description: Key Points: - Freshwater input has significantly contributed to the surface warming at the peak of the 1995 Benguela Niño - Anomalously high river discharge and precipitation increased stratification and reduced turbulent heat loss by creating barrier layers - Combination of high freshwater input and strong poleward surface current might play a role in temperature variability off Angola Benguela Nino events are characterized by strong warm sea surface temperature (SST) anomalies off the Angolan and Namibian coasts. In 1995, the strongest event in the satellite era took place, impacting fish availability in both Angolan and Namibian waters. In this study, we use direct observations, satellite data, and reanalysis products to investigate the impact that the up-until-now unnoticed mechanism of freshwater input from Congo River discharge (CRD) and precipitation had on the evolution of the 1995 Benguela Nino. In the onset phase of the event, anomalous rainfall in November/December 1994 at around 6 degrees S, combined with a high CRD, generated a low salinity plume. The plume was advected into the Angola-Namibia region in the following February/March 1995 by an anomalously strong poleward surface current generated by the relaxation of the southerly winds and shifts in the coastal wind stress curl. The presence of this low surface salinity anomaly of about -2 psu increased ocean stability by generating barrier layers, thereby reducing the turbulent heat loss, since turbulent mixing acted on a weak vertical temperature gradient. A mixed layer heat budget analysis demonstrates that southward advection of Angolan waters drove the warming at the onset, while reduced mixing played the main role at the event's peak. We conclude that a freshwater input contributed to the SST increase in this exceptionally strong event and suggest that this input can influence the SST variability in Angola-Namibia waters through a combination of high CRD, precipitation, and the presence of a strong poleward surface current. Benguela Nino events are characterized by excessive warming of the sea surface temperature off the Angolan and Namibian coasts. One of the strongest-ever recorded warm events dates back to 1995, impacting fish availability in both Angolan and Namibian waters. In our research, we investigate if freshwater from rain and from the Congo River could have impacted the evolution of this 1995 Benguela Nino. In the event's early stage, high precipitation and river discharge generated a low salinity pool at the Congo River mouth, which in February/March 1995 was taken to the south by an exceptionally strong surface current, generated by changes in wind strength and direction at the African coast. This low sea surface salinity in a shallow layer in the upper meters of the ocean increased the ocean's stability. As the stabilized waters diminished the usual mixing from the depths below which cools down the surface waters, it contributed to an increase in warming in the surface layer of the ocean. We conclude that the warming of the surface waters in the region was indeed influenced by the combination of high precipitation and high Congo River discharge with a strong surface current toward the south. Freshwater input has significantly contributed to the surface warming at the peak of the 1995 Benguela Nino Anomalously high river discharge and precipitation increased stratification and reduced turbulent heat loss by creating barrier layers Combination of high freshwater input and strong poleward surface current might play a role in temperature variability off Angola

Description: Iodine cycling in the ocean is closely linked to productivity, organic carbon export, and oxygenation. However, iodine sources and sinks at the seafloor are poorly constrained, which limits the applicability of iodine as a biogeochemical tracer. We present pore water and solid phase iodine data for sediment cores from the Peruvian continental margin, which cover a range of bottom water oxygen concentrations, organic carbon rain rates and sedimentation rates. By applying a numerical reaction‐transport model, we evaluate how these parameters determine benthic iodine fluxes and sedimentary iodine‐to‐organic carbon ratios (I:C org ) in the paleo‐record. Iodine is delivered to the sediment with organic material and released into the pore water as iodide (I − ) during early diagenesis. Under anoxic conditions in the bottom water, most of the iodine delivered is recycled, which can explain the presence of excess dissolved iodine in near‐shore anoxic seawater. According to our model, the benthic I − efflux in anoxic areas is mainly determined by the organic carbon rain rate. Under oxic conditions, pore water dissolved I − is oxidized and precipitated at the sediment surface. Much of the precipitated iodine re‐dissolves during early diagenesis and only a fraction is buried. Particulate iodine burial efficiency and I:C org burial ratios do increase with bottom water oxygen. However, multiple combinations of bottom water oxygen, organic carbon rain rate and sedimentation rate can lead to identical I:C org , which limits the utility of I:C org as a quantitative oxygenation proxy. Our findings may help to better constrain the ocean's iodine mass balance, both today and in the geological past. Key Points The impact of early diagenesis on benthic iodine fluxes and iodine burial was quantitatively evaluated using a reaction‐transport model Dissolved iodine anomalies in the water column are indicative of benthic efflux from anoxic sediments with high organic carbon turnover Not only bottom water oxygen but also organic carbon delivery and sedimentation rate determine sedimentary iodine‐to‐organic carbon ratios

Description: The understanding of silicate weathering and its role as a sink for atmospheric CO 2 is important to get a better insight into how the Earth shifts from warm to cool climates. The lithium isotope composition (δ 7 Li) of marine carbonates can be used as a proxy to track the past chemical weathering of silicates. A high‐resolution δ 7 Li record would be helpful to evaluate the role of silicate weathering during the late Cretaceous climate cooling. Here, we assess chalk as a potential archive for reconstructing Late Cretaceous seawater Li isotope composition by comparing Maastrichtian chalk from Northern Germany (Hemmoor, Kronsmoor) to a Quaternary coccolith ooze from the Manihiki Plateau (Pacific Ocean) as a lithological analog to modern conditions. We observe a negative offset of 3.9 ± 0.6‰ for the coccolith ooze relative to the modern seawater Li isotope composition (+31.1 ± 0.3‰; 2SE; n = 54), a value that falls in the range of published offsets for modern core‐top samples and for brachiopod calcite. Further, the negative offset between the Li isotope compositions of Manihiki coccolith ooze and modern planktonic foraminifera is 2.3 ± 0.6‰. Although chalk represents a diagenetically altered modification of pelagic nannofossil ooze, manifested by changes in the composition of trace elements, we observe a consistent offset of Li isotope data between Maastrichtian chalk and Maastrichtian planktonic foraminiferal data (−1.4 ± 0. 5‰) that lies within the uncertainty of modern values. We therefore suggest that chalk can be used as a reliable archive for δ 7 Li reconstructions. Key Points Chalk is a reliable archive for the Li isotope composition of seawater Coccolith ooze has a negative offset of 3.9 ± 0.6‰ from modern seawater for Li isotope ratios The estimated mean value for the late Maastrichtian seawater Li isotope composition is +27.5 ± 1.0‰

Description: Compositional variations of amphibole stratigraphically recovered from multiple eruptions at a given volcano have a great potential to archive long-term magmatic processes in its crustal plumbing system. Calcic amphibole is a ubiquitous yet chemically and texturally diverse mineral at Mount St. Helens (MSH), where it occurs in dacites and in co-magmatic enclaves throughout the Spirit Lake stage (last ~4000 years of eruptive history). It forms three populations with distinct geochemical trends in key major and trace elements, which are subdivided into a high-Al (11–14.5 wt% Al2O3), a medium-Al (10–12.5 wt% Al2O3), and a low-Al (7.5–10 wt% Al2O3) amphibole population. The oldest investigated tephra record (Smith Creek period, 3900–3300 years BP) yields a bimodal amphibole distribution in which lower-crustal, high-Al amphibole cores (crystallized dominantly from basaltic andesite to andesite melts) and upper-crustal, low-Al amphibole rims (crystallized from rhyolitic melt) document occasional recharge of a shallow silicic mush by a more mafic melt from a lower-crustal reservoir. The sudden appearance of medium-Al amphiboles enriched in incompatible trace elements in eruptive periods younger than 2900 years BP is associated with a change in reservoir conditions toward hotter and drier magmas, which indicates recharge of the shallow silicic reservoir by basaltic melt enriched in incompatible elements. Deep-crystallizing, high-Al amphibole, however, appears mostly unaffected by such incompatible-element-enriched basaltic recharge, suggesting that these basalts bypass the lower crustal reservoir. This could be the result of the eastward offset position of the lower crustal reservoir relative to the upper crustal storage zone underneath the MSH edifice. Amphibole has proven to be a sensitive geochemical archive for uncovering storage conditions of magmas at MSH. In agreement with geophysical observations, storage and differentiation have occurred in two main zones: an upper crustal and lower crustal reservoir (the lower one being chemically less evolved). The upper crustal silicic reservoir, offset to the west of the lower crustal reservoir, has captured compositionally unusual mafic recharge (drier, hotter, and enriched in incompatible trace elements in comparison to the typical parental magmas in the region), resulting in an increased chemical diversity of amphiboles and their carrier intermediate magmas, in the last ~3000 years of MSH’s volcanic record.

Description: This study investigates extreme wet and dry conditions over the humid tropics and their connections to the variability of the tropical ocean basins using observations and a multi-model ensemble of 24 state-of-the-art coupled climate models, for the 1930–2014 period. The extreme wet (dry) conditions are consistently linked to Central Pacific La Niña (Eastern Pacific El Niño), the weakest being the Congo basin, and homogeneous patterns of sea surface temperature (SST) variability in the tropical Indian Ocean. The Atlantic exhibits markedly varying configurations of SST anomalies, including the Atlantic Niño and pan-Atlantic decadal oscillation, with non-symmetrical patterns between the wet and dry conditions. The oceanic influences are associated with anomalous convection and diabatic heating partly related to variations in the strength of the Walker Circulation. The observed connection between the Amazon basin, as well as the Maritime continent, and the Indo-Pacific variability are better simulated than that of the Congo basin. The observed signs of the Pacific and Indian SST anomalies are reversed for the modelled Congo basin extreme conditions which are, instead, tied to the Atlantic Niño/Niña variability. This Atlantic–Congo basin connection is related to a too southerly location of the simulated inter-tropical convergence zone that is associated with warm SST biases over the Atlantic cold tongue. This study highlights important teleconnections and model improvements necessary for the skillful prediction of extreme precipitation over the humid tropics.

Description: Key Points: - North Atlantic biases are alleviated by an eddying nested ocean configuration embedded in a global climate model, FOCI-VIKING10 - It is indicated that reduction of the North Atlantic biases could improve the representation of NAO sub-decadal (8 years) variability - For detecting weak external imprints with limited computational resources, an ensemble with a coarse-resolution model is favorable Increasing the horizontal resolution of an ocean model is frequently seen as a way to reduce the model biases in the North Atlantic, but we are often limited by computational resources. Here, a two-way nested ocean model configuration (VIKING10) that consists of a high-resolution (1/10°) component and covers the northern North Atlantic, is embedded in a 1/2° ocean grid as part of the global chemistry-climate model, FOCI (called FOCI-VIKING10). This configuration yields a significantly improved path of the North Atlantic current (NAC), which here reduces the North Atlantic cold bias by ∼50%. Compared with the coarse-resolution, non-eddying model, the improved thermal state of upper ocean layers and surface heat fluxes in a historical simulation based on FOCI-VIKING10 are beneficial for simulating the subdecadal North Atlantic Oscillation (NAO) variability (i.e., a period of 8 years). A northward drift of the NAO-forced ocean thermal anomalies as seen in observations and the eddying FOCI-VIKING10, provide a lagged ocean feedback to the NAO via changes in the net surface heat flux, leading to the NAO periodicity of 8 years. This lagged feedback and the 8 years variability of the NAO cannot be captured by the non-eddying standard FOCI historical simulation. Furthermore, the argumentative responses of the North Atlantic to the 11-year solar cycle are re-examined in this study. The reported solar-induced NAO-like responses are confirmed in the 9-member ensemble mean based on FOCI but with low robustness among individual members. A lagged NAO-like response is only found in the nested eddying simulation but absent from the non-eddying reference simulation, suggesting North Atlantic biases importantly limit climate model capability to realistically solar imprints in North Atlantic climate.

Description: RV MARIA S. MERIAN MSM126 “Jellyweb Madeira” 9. Februar – 4. März 2024 3.Wochenbericht (19. – 25. Februar 2024)

Description: Ocean alkalinity enhancement (OAE) stands as a promising carbon dioxide removal technology. Yet, this solution to climate change entails shifts in water chemistry with unknown consequences for marine fish that are critical to ecosystem health and food security. With a laboratory and mesocosm experiment, we show that early life stages of fish can be resistant to OAE. We examined metabolic rate, swimming behavior, growth and survival in Atlantic herring (Clupea harengus) and other temperate coastal fish species. Neither direct physiological nor indirect food web-mediated impacts of OAE were apparent. This was despite non-CO2-equilibrated OAE (ΔTA = +600 µmol kg-1) that induces strong perturbations (ΔpH = +0.7, pCO2 = 75 µatm) compared to alternative deployment scenarios. Whilst our results give cause for optimism regarding the large-scale application of OAE, other life history stages (embryos) and habitats (open ocean) may prove more vulnerable. Still, our study across ecological scales (organism to community) and exposure times (short- to long-term) suggests that some fish populations, including key fisheries species, may be resilient to the carbonate chemistry changes under OAE.

Description: Enhancing ocean productivity by artificial upwelling is evaluated as a nature-based solution for food security and climate change mitigation. Fish production is intended through diatom-based plankton food webs as these are assumed to be short and efficient. However, our findings from mesocosm experiments on artificial upwelling in the oligotrophic ocean disagree with this classical food web model. Here, diatoms did not reduce trophic length and instead impaired the transfer of primary production to crustacean grazers and small pelagic fish. The diatom-driven decrease in trophic efficiency was likely mediated by changes in nutritional value for the copepod grazers. Whilst diatoms benefitted the availability of essential fatty acids, they also caused unfavorable elemental compositions via high carbon-to-nitrogen ratios (i.e. low protein content) to which the grazers were unable to adapt. This nutritional imbalance for grazers was most pronounced in systems optimized for CO 2 uptake through carbon-to-nitrogen ratios well beyond Redfield. A simultaneous enhancement of fisheries production and carbon sequestration via artificial upwelling may thus be difficult to achieve given their opposing stoichiometric constraints. Our study suggest that food quality can be more critical than quantity to maximize food web productivity during shorter-term fertilization of the oligotrophic ocean.

Description: Weather forecasts can enhance the utilization of scientific irrigation scheduling tools, crucial for maximizing agricultural water use efficiency. This study employed quantitative weather forecasts of 3-, 7- and 14-day lead times from a weather application programming interface (API) to generate irrigation schedules using the AquaCrop-OSPy model for maize, cotton and sorghum under different regulated deficit irrigation scenarios. The study aimed to determine the suitability of forecast lengths for irrigation scheduling under varying pumping capacities of center pivots (114 m3h−1, 182 m3 h−1 and 250 m3 h−1) in the Texas High Plains and Rio Grande Basin regions, United States. A comparative analysis was carried out to evaluate the irrigation schedules and corresponding crop yields simulated using forecasted and observed weather data. Results indicated that using shorter forecast time allowed the crop model to capture more precise variations in weather patterns, however, shorter lead times also caused over-irrigation in some scenarios. Use of longer lead times tended to be less suitable for scheduling irrigation during water-sensitive growth stages. Center pivots with large pumping capacities and application rates benefited more from longer forecast lengths due to their ability to adapt to weather fluctuations. Unplanned irrigation application occurred in some instances, primarily attributed to uncertainties in weather forecasts and limitations of the crop model. The approach developed and evaluated in this study supports water conservation efforts by promoting scientific irrigation scheduling in weather-data-poor and low adoption regions.

Description: The Nile basin is the second largest basin in Africa and one of the regions experiencing high climatic diversity with variability of precipitation and deteriorating water resources. As climate change is affecting most of the hydroclimatic variables across the world, this study assesses whether historical changes in river flow and sediment loads at selected gauges in the Nile basin can be attributed to climate change. An impact attribution approach is employed by constraining a process-based model with a set of factual and counterfactual climate forcing data for 69 years (1951–2019), from the impact attribution setup of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3a). To quantify the role of climate change, we use the non-parametric Mann-Kendall test to identify trends and calculate the differences in long-term mean annual river flow and sediment load simulations between a model setup using factual and counterfactual climate forcing data. Results for selected river stations in the Lake Victoria basin show reasonable evidence of a long-term historical increase in river flows (two stations) and sediment load (one station), largely attributed to changes in climate. In contrast, within the Blue Nile and Main Nile basins, there is a slight decrease of river flows at four selected stations under factual climate, which can be attributed to climate change, but no significant changes in sediment load (one station). These findings show spatial differences in the impacts of climate change on river flows and sediment load in the study area for the historical period.

Description: Correlation does not necessarily imply causation, and this is why causal methods have been developed to try to disentangle true causal links from spurious relationships. In our study, we use two causal methods, namely, the Liang–Kleeman information flow (LKIF) and the Peter and Clark momentary conditional independence (PCMCI) algorithm, and we apply them to four different artificial models of increasing complexity and one real-world case study based on climate indices in the Atlantic and Pacific regions. We show that both methods are superior to the classical correlation analysis, especially in removing spurious links. LKIF and PCMCI display some strengths and weaknesses for the three simplest models, with LKIF performing better with a smaller number of variables and with PCMCI being best with a larger number of variables. Detecting causal links from the fourth model is more challenging as the system is nonlinear and chaotic. For the real-world case study with climate indices, both methods present some similarities and differences at monthly timescale. One of the key differences is that LKIF identifies the Arctic Oscillation (AO) as the largest driver, while the El Niño–Southern Oscillation (ENSO) is the main influencing variable for PCMCI. More research is needed to confirm these links, in particular including nonlinear causal methods.

Description: The possibility that the Amazon forest system could soon reach a tipping point, inducing large-scale collapse, has raised global concern. For 65 million years, Amazonian forests remained relatively resilient to climatic variability. Now, the region is increasingly exposed to unprecedented stress from warming temperatures, extreme droughts, deforestation and fires, even in central and remote parts of the system1. Long existing feedbacks between the forest and environmental conditions are being replaced by novel feedbacks that modify ecosystem resilience, increasing the risk of critical transition. Here we analyse existing evidence for five major drivers of water stress on Amazonian forests, as well as potential critical thresholds of those drivers that, if crossed, could trigger local, regional or even biome-wide forest collapse. By combining spatial information on various disturbances, we estimate that by 2050, 10% to 47% of Amazonian forests will be exposed to compounding disturbances that may trigger unexpected ecosystem transitions and potentially exacerbate regional climate change. Using examples of disturbed forests across the Amazon, we identify the three most plausible ecosystem trajectories, involving different feedbacks and environmental conditions. We discuss how the inherent complexity of the Amazon adds uncertainty about future dynamics, but also reveals opportunities for action. Keeping the Amazon forest resilient in the Anthropocene will depend on a combination of local efforts to end deforestation and degradation and to expand restoration, with global efforts to stop greenhouse gas emissions.

Description: Recent studies have begun to explore the potential of enhanced benthic weathering (EBW) in the Baltic Sea as a measure for climate change mitigation. To augment the understanding of EBW under seasonally changing conditions, this study aims to investigate weathering processes under anoxia to hypoxia in corrosive bottom waters, which reflect late summer conditions in the Baltic Sea. Dunite and calcite were added to sediment cores retrieved from Eckernförde Bay (Western Baltic Sea) with a constant flow-through of deoxygenated, CO 2 -enriched Baltic Sea bottom water. The addition of both materials increased benthic alkalinity release by 2.94 μmol cm −2 d −1 (calcite) and 1.12 μmol cm −2 d −1 (dunite), compared to the unamended control experiment. These excess fluxes are significantly higher than those obtained under winter conditions. The comparison with bottom water oxygen concentrations emphasizes that highest fluxes of alkalinity were associated with anoxic phases of the experiment. An increase in Ca and Si fluxes showed that the enhanced alkalinity fluxes could be attributed to calcite and dunite weathering. First order rate constants calculated based on these data were close to rates published in previous studies conducted under different conditions. This highlights the suitability of these proxies for mineral dissolution and justifies the use of these rate constants in modeling studies investigating EBW in the Baltic Sea and areas with similar chemical conditions. Generally stable pH profiles over the course of the experiment, together with the fact that the added minerals remained on the sediment surface, suggest that corrosive bottom waters were the main driving factor for the dissolution of the added minerals. These factors have important implications for the choice of mineral and timing for EBW as a possible marine carbon dioxide removal method in seasonally hypoxic to anoxic regions of the Baltic Sea.

Description: Highlights • Negligible Ba removal observed in the Rainbow hydrothermal system. • Insignificant modification of Ba isotope composition of the vent fluid endmember. • Rainbow vent introduces isotopically light Ba (−0.17) to the deep Atlantic Ocean. • Hydrothermal inputs contribute 4.6 ± 2.2 Gmol/yr Ba to the ocean. Abstract The marine barium (Ba) cycle is closely connected to the short-timescale carbon cycle, and Ba serves as a valuable paleo proxy for export production, ocean alkalinity, and terrestrial inputs. However, the marine Ba budget is poorly constrained, particularly regarding the fluxes of hydrothermally sourced Ba, which hinders our understanding of the Ba cycle and use of Ba-based proxies. Recent studies have suggested a modern source-sink imbalance of Ba isotopes in the global ocean, with sources being overall isotopically heavier than the sinks, and the hydrothermal Ba inputs were considered isotopically heavy sources. In this study, we present the first investigation of Ba and its isotopes in a non-buoyant hydrothermal plume based on dissolved and particulate samples collected from the Rainbow hydrothermal vent field on the Mid-Atlantic Ridge. Our data reveal strong hydrothermal signals at near-field stations, as evidenced by helium isotopes, accompanied by elevated concentrations of dissolved and particulate Ba. Dissolved Ba isotope compositions (δ138Ba) in hydrothermally influenced deep waters (∼0.3 ) are lighter than at similar depths of far-field stations (∼0.45 ) in the Atlantic Ocean. The concentrations and isotopic compositions of dissolved and labile particulate Ba in the non-buoyant hydrothermal plume can be explained by conservative mixing between a Ba-enriched hydrothermal component and North Atlantic Deep Water. By extrapolating the correlations to the vent fluid endmember, our results suggest that there is negligible removal of Ba, and insignificant modification of Ba isotopic signatures, from the vent fluid endmember to the non-buoyant hydrothermal plume. This indicates that the Rainbow hydrothermal system introduces isotopically light Ba (−0.17 ± 0.05 ) to the deep Atlantic Ocean. We estimate that global hydrothermal inputs of Ba are 4.6 ± 2.2 Gmol/yr. These observations highlight the potential of hydrothermal Ba to be an isotopically light source component of the marine Ba isotope budget.

Description: Mixed turbidite–contourite depositional systems result from interactions between down‐slope turbidity currents and along‐slope bottom currents, comprising excellent records of past oceanographic currents. Modern and ancient systems have been widely documented along the continental margins of the Atlantic Ocean. Yet, few examples have so far been identified on the North‐west African continental margin, limiting understanding of the sedimentary and palaeoceanographic evolution in this area. This work uses two‐dimensional seismic reflection profiles to report, for the first time, the presence of three giant sediment mounds beneath the headwall region of the Sahara Slide Complex. The sediment mounds are elongated and separated by two broad canyons, showing a north‐west/south‐east orientation that is roughly perpendicular to the continental margin. These mounds are 24 to 37 km long and 12 to 17 km wide, reaching a maximum height of ca 1000 m. Numerous slide scarps are observed within and along the flanks of the mounds, hinting at the occurrence of submarine landslides during their development. Based on their geometries, external shapes, internal seismic architecture and stratigraphic stacking patterns, it is proposed that these sediment mounds comprise down‐slope elongated mounded drifts formed in a mixed turbidite–contourite system during four evolutionary stages: onset, growth, maintenance and burial. The significance of this work is that it demonstrates the gradual transition from a turbidite system to a full mixed turbidite–contourite system to be associated, in the study area, with the establishment of strong ocean currents along north‐west Africa.

Description: Highlights: • Transcriptomic immune response assessments in seahorse (Hippocampus erectus). • Seahorses exposed in two phases to heat-killed Vibrio and Tenacibaculum strains. • Adaptive immune memory evidence (double-exposed) and increased naivety to Tenacibaculum. • Upregulated gene expression pertaining to potential innate ‘trained immunity’. • Trained immunity potential compensator for deduced MHC II loss of function. Evolutionary adaptations in the Syngnathidae teleost family (seahorses, pipefish and seadragons) culminated in an array of spectacular morphologies, key immune gene losses, and the enigmatic male pregnancy. In seahorses, genome modifications associated with immunoglobulins, complement, and major histocompatibility complex (MHC II) pathway components raise questions concerning their immunological efficiency and the evolution of compensatory measures that may act in their place. In this investigation heat-killed bacteria (Vibrio aestuarianus and Tenacibaculum maritimum) were used in a two-phased experiment to assess the immune response dynamics of Hippocampus erectus. Gill transcriptomes from double and single-exposed individuals were analysed in order to determine the differentially expressed genes contributing to immune system responses towards immune priming. Double-exposed individuals exhibited a greater adaptive immune response when compared with single-exposed individuals, while single-exposed individuals, particularly with V. aestuarianus replicates, associated more with the innate branch of the immune system. T. maritimum double-exposed replicates exhibited the strongest immune reaction, likely due to their immunological naivety towards the bacterium, while there are also potential signs of innate trained immunity. MHC II upregulated expression was identified in selected V. aestuarianus-exposed seahorses, in the absence of other pathway constituents suggesting a possible alternative or non-classical MHC II immune function in seahorses. Gene Ontology (GO) enrichment analysis highlighted prominent angiogenesis activity following secondary exposure, which could be linked to an adaptive immune process in seahorses. This investigation highlights the prominent role of T-cell mediated adaptive immune responses in seahorses when exposed to sequential foreign bacteria exposures. If classical MHC II pathway function has been lost, innate trained immunity in syngnathids could be a potential compensatory mechanism.

Description: Rhodaliids, a specific family of siphonophores inhabiting the benthic zone, have remained enigmatic due to their rarity and elusive nature. These unique organisms, primarily found in open ocean habitats, exhibit distinctive features and are characterized by complex structures. During the Red Sea Decade Expedition, two rhodaliid specimens were collected at the sea bed at water depths of 438 and 495 meters. Regardless of challenges in specimen preservation, detailed morphological analysis revealed unique characteristics. Genetic analysis, employing the 16S rRNA marker, revealed one specimen closely related to Thermopalia taraxaca , while the taxonomic traits of this specimen suggested the identification of Archangelopsis jagoa . While most of the morphological features of the second specimen were also very similar to A. jagoa , some differences in coloration suggest the discovery of either an unusual colour variant or a potential new species within this genus. Notably, this study reports the first sequencing of A. jagoa . This species demonstrated a capacity to thrive in low-oxygen environments, challenging conventional assumptions about their habitat requirements. Despite difficulties in specimen handling and genetic analysis limitations due to a lack of comprehensive data, this research sheds light on the elusive world of benthic rhodaliids.

Description: “Flip‐flop” detachment mode represents an endmember type of lithosphere‐scale faulting observed at almost amagmatic sections of ultraslow‐spreading mid‐ocean ridges. Recent numerical experiments using an imposed steady temperature structure show that an axial temperature maximum is essential to trigger flip‐flop faults by focusing flexural strain in the footwall of the active fault. However, ridge segments without significant melt budget are more likely to be in a transient thermal state controlled, at least partly, by the faulting dynamics themselves. Therefore, we investigate which processes control the thermal structure of the lithosphere and how feedbacks with the deformation mechanisms can explain observed faulting patterns. We present results of 2‐D thermo‐mechanical numerical modeling including serpentinization reactions and dynamic grain size evolution. The model features a novel form of parametrized hydrothermal cooling along fault zones as well as the thermal and rheological effects of periodic sill intrusions. We find that the interplay of hydrothermal fault zone cooling and periodic sill intrusions in the footwall facilitates the flip‐flop detachment mode. Hydrothermal cooling of the fault zone pushes the temperature maximum into the footwall, while intrusions near the temperature maximum further weaken the rock and promote the formation of new faults with opposite polarity. Our model allows us to put constraints on the magnitude of two processes, and we obtain most reasonable melt budgets and hydrothermal heat fluxes if both are considered. Furthermore, we frequently observe two other faulting modes in our experiments complementing flip‐flop faulting to yield a potentially more robust alternative interpretation for existing observations. Plain Language Summary At mid‐ocean ridges, two plates diverge and new seafloor is created. The nature and appearance of this new seafloor strongly depend on spreading velocity and the availability of magmatic melts. At one of the melt‐poorest and slowest‐spreading ridges, a special form of large‐scale tectonic faults, so‐called flip‐flop detachments, can be observed. Tectonic faults can act as pathways for fluids circulating through the seafloor, which provides a significant cooling effect for the young plate. The interplay of magmatic activity, faulting and fluid circulation is evident at many different ridges with different magmatic activity and spreading rates. Flip‐flop faulting is restricted to only a few ridge sections worldwide, and we here investigate the prerequisites for this special spreading mode. To do so, we set up a computer model of an ultraslow‐spreading mid‐ocean ridge including the effects of sparse magmatism as well as the cooling effect associated with fluid circulation. We find that feedbacks between faulting dynamics, hydrothermal cooling and magmatic activity control the magnitude and spatial location of each individual process. Seafloor and subsurface observations are best explained by calculations with moderate melt input and hydrothermal circulation acting together. Key Points We implemented hydrothermal cooling and magmatic intrusion in a thermo‐mechanical model to explain detachment faulting at ultraslow ridges Stable flip‐flop detachment faulting is observed for setups considering both melt input and hydrothermal heat fluxes at realistic magnitudes Two other faulting modes frequently observed in our model offer potential alternative interpretations for existing seafloor observations

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.

Description: Highlights • Solutions to the climate crisis are not ahistorical. • Both social and technical processes explain their rise (or fall) on the agenda. • Thinking about ocean CDR closely co-evolved with scientific understandings of global climate change. • Ocean CDR methods have followed cycles of hype, controversy and disappointment. • Key sociotechnical configurations and narrative changes explain the new hype around ocean CDR. Abstract While the ocean has long been portrayed as a victim of climate change, threatened by ocean warming and acidification, it is now increasingly framed as a key solution to the climate crisis. In particular, the promising carbon sequestration potential of the ocean is being emphasised. In this paper, we seek to historicise the practices, discourses and actors that have constructed the ocean as a climate change solution space. We conceptualise the debate about the mitigation potential of the ocean as a contested site of governance, where varying actors form alliances and different sociotechnical narratives about climate action play out. Using an innovative quali-quantitative methodology which combines scientometrics with document analysis, observational fieldwork, and interviews, we outline three historical phases in the history of ocean carbon sequestration that follow recurring cycles of hype, controversy and disappointment. We argue that the most recent hype around ocean carbon sequestration was not triggered by a technological breakthrough or a reduction in scientific uncertainty, but by new socio-technical configurations and coalitions. We conclude by showing that how climate change solutions are put on the agenda and become legitimised is both a scientific and political process, linked to how science frames the climate crisis, and ultimately, its governance.

Description: Ocean alkalinity enhancement (OAE) is considered for the long-term removal of gigatons of carbon dioxide (CO2) from the atmosphere to achieve our climate goals. Little is known, however, about the ecosystem-level changes in biogeochemical functioning that may result from the chemical sequestration of CO2 in seawater, and how stable the sequestration is. We studied these two aspects in natural plankton communities under carbonate-based, CO2-equilibrated OAE in the nutrient-poor North Atlantic. During a month-long mesocosm experiment, the majority of biogeochemical pools, including inorganic nutrients, particulate organic carbon and phosphorus as well as biogenic silica, remained unaltered across all OAE levels of up to a doubling of ambient alkalinity (+2400 µeq kg-1). Noticeable exceptions were a minor decrease in particulate organic nitrogen and an increase in the carbon to nitrogen ratio (C:N) of particulate organic matter in response to OAE. Thus, in our nitrogen limited system, nitrogen turnover processes appear more susceptible than those of other elements leading to decreased food quality and increased organic carbon storage. However, alkalinity and chemical CO2 sequestration were not stable at all levels of OAE. Two weeks after alkalinity addition, we measured a loss of added alkalinity and of the initially stored CO2 in the mesocosm where alkalinity was highest (+2400 µeq kg-1, Ωaragonite ~10). The loss rate accelerated over time. Additional tests showed that such secondary precipitation can be initiated by particles acting as precipitation nuclei and that this process can occur even at lower levels of OAE. In conclusion, on the one hand, our study under carbonate-based OAE where the carbon is already sequestered, the risk of major and sustained impacts on biogeochemical functioning may be low in the nutrient-poor ocean. On the other hand, the durability of carbon sequestration using OAE could be constrained by alkalinity loss in supersaturated waters with precipitation nuclei present. Our study provides evaluation of ecosystem impacts of an idealised OAE deployment for monitoring, reporting and verification (MRV) in an oligotrophic system. Whether biogeochemical functioning is resilient to more technically simple and economically more viable approaches that induce stronger water chemistry perturbations remains to be seen.

Description: Climate change is driving compositional shifts in ecological communities directly by affecting species and indirectly through changes in species interactions. For example, competitive hierarchies can be inversed when competitive dominants are more susceptible to climate change. The brown seaweed Fucus vesiculosus is a foundation species in the Baltic Sea, experiencing novel interactions with the invasive red seaweed Gracilaria vermiculophylla, which is known for its high tolerance to environmental stress. We investigated the direct and interactive effects of warming and co-occurrence of the two algal species on their performance, by applying four climate change-relevant temperature scenarios: 1) cooling ) 2 °C below ambient – representing past conditions), 2) ambient summer temperature (18 °C), 3) IPCC RCP2.6 warming scenario (1 °C above ambient), and 4) RCP8.5 warming (3 °C above ambient) for 30 days and two compositional levels (mono and co-cultured algae) in a fully-crossed design. The RCP8.5 warming scenario increased photosynthesis, respiration, and nutrients' uptake rates of mono- and co-cultured G. vermiculophylla while growth was reduced. An increase in photosynthesis and essential nutrients' uptake and, at the same time, a growth reduction might result from increasing stress and energy demand of G. vermiculophylla under warming. In contrast, the growth of mono-cultured F. vesiculosus significantly increased in the highest warming treatment (+3 °C). The cooling treatment (−2 °C) exerted a slight negative effect only on co-cultured F. vesiculosus photosynthesis, compared to the ambient treatment. Interestingly, at ambient and warming (RCP2.6 and RCP8.5 scenarios) treatments, both F. vesiculosus and G. vermiculophylla appear to benefit from the presence of each other. Our results suggest that short exposure of F. vesiculosus to moderate or severe global warming scenarios may not directly affect or even slightly enhance its performance, while G. vermiculophylla net performance (growth) could be directly hampered by warming.

Description: RV MARIA S. MERIAN MSM126 “Jellyweb Madeira” 9. Februar – 4. März 2024 4.Wochenbericht (26.Februar – 03. März 2024)

Description: Anticipatory humanitarian assistance is a novel approach to aid in the context of weather disasters, drawing on meteorological forecasts. Using a randomized study design, we analyze the impact of anticipatory cash transfers distributed to pastoralist households in Mongolia during an extreme winter event. We do not find overall effects on livestock assets, income, investments, or consumption across the study population. No heterogenous effects are found for different levels of disaster intensity. However, there is robust evidence that cash transfers benefited households with lower pre-treatment wealth. The paper concludes by highlighting practical challenges in evaluating (anticipatory) humanitarian interventions.

Description: The Texas power grid on the Gulf Coast of the United States is frequently hit by tropical cyclones (TCs) causing widespread power outages, a risk that is expected to substantially increase under global warming. Here we introduce a new approach that combines a probabilistic line failure model with a network model of the Texas grid to simulate the spatio-temporal co-evolution of wind-induced failures of high-voltage transmission lines and the resulting cascading power outages from seven major historical TCs. The approach allows reproducing observed supply failures. In addition, compared to existing static approaches, it provides a notable advantage in identifying critical lines whose failure can trigger large supply shortages. We show that hardening only 1% of total lines can reduce the likelihood of the most destructive type of outage by a factor of between 5 and 20. The proposed modelling approach could represent a so far missing tool for identifying effective options to strengthen power grids against future TC strikes, even under limited knowledge.

Description: Large gaps remain in our understanding of the vulnerability of specific animal taxa and regions to climate change, especially regarding extreme climate impact events. Here, we assess African apes, flagship and highly important umbrella species for sympatric biodiversity. We estimated past (1981–2010) and future exposure to climate change impacts across 363 sites in Africa for RCP2.6 and RCP6.0 for near term (2021–2050) and long term (2071–2099). We used fully harmonized climate data and data on extreme climate impact events from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP). Historic data show that 171 sites had positive temperature anomalies for at least nine of the past ten years with the strongest anomalies (up to 0.56°C) estimated for eastern chimpanzees. Climate projections suggest that temperatures will increase across all sites, while precipitation changes are more heterogeneous. We estimated a future increase in heavy precipitation events for 288 sites, and an increase in the number of consecutive dry days by up to 20 days per year (maximum increase estimated for eastern gorillas). All sites will be frequently exposed to wildfires and crop failures in the future, and the latter could impact apes indirectly through increased deforestation. 84% of sites are projected to be exposed to heatwaves and 78% of sites to river floods. Tropical cyclones and droughts were only projected for individual sites in western and central Africa. We further compiled available evidence on how climate change impacts could affect apes, for example, through heat stress and dehydration, a reduction in water sources and fruit trees, and reduced physiological performance, body condition, fertility, and survival. To support necessary research on the sensitivity and adaptability of African apes to climate change impacts, and the planning and implementation of conservation measures, we provide detailed results for each ape site on the open-access platform A.P.E.S. Wiki.

Description: The EU and its member countries have been laggards in using forest carbon to reduce EU emissions. The European Green Deal aims to change this. As part of its long-term emissions reductions, the EU aims to offset this by creating land-based carbon sinks, especially forest carbon sinks as well as carbon capture and storage. This chapter focuses on the role of forest carbon as part of the EU's climate policies towards achieving net-zero greenhouse gas emissions by 2050. It furthermore examines the European Commission's proposed forest strategy and its proposal for a revised LULUCF Regulation. The chapter shows that the logic of appropriateness dominates the European Commission's forest policies. Finally, the chapter makes policy recommendations on how the EU could credibly use long-term carbon sinks to achieve climate neutrality.

Description: Marine heatwaves (MHWs) are widely recognized as prolonged periods of significantly elevated sea surface temperatures, leading to substantial adverse impacts on marine ecosystems. However, a comprehensive understanding of their characteristics and potential changes under climate change in the South China Sea (SCS, 0 ∼ 25°N, 105 ∼ 125°E) remains insufficient. Here, utilizing the OISST V2.0 reanalysis dataset, our study first examines MHW characteristics and their trends in the SCS during the historical period (1982 ∼ 2014). Then, in accordance with the criteria established in this study, GFDL-ESM4, EC-Earth3-Veg, NESM3, EC-Earth3, and GFDL-CM4 are identified from the CMIP6 ensemble of 19 models for their enhanced simulations of historical MHW characteristics. Moreover, considering that the fixed and sliding threshold methods offer distinct perspectives on the future evolution of MHWs, we employ both approaches to evaluate MHW characteristics under projected scenarios for the future period (2015 ∼ 2100) and subsequently compare the disparities between the two methodologies. The outcomes obtained using these methods consistently indicate that MHWs in the SCS are anticipated to intensify and persist for longer durations in the future. Besides, addressing seasonal variability, the peak intensity of MHWs falls in May during both the historical period and the four projected future scenarios. This study provides valuable insights into the behavior of MHWs in the SCS within the context of climate change, underscoring the urgency of adopting effective mitigation strategies. Especially, the use of two definition methods provides a more comprehensive set of information for understanding the future changes of MHWs in the SCS.

Description: Coordinates: Median Latitude: 49.36135 * Median Longitude: -128.05476 * South-bound Latitude: 47.55729 * West-bound Longitude: -129.20661 * North-bound Latitude: 50.29167 * East-bound Longitude: -126.30441 Abstract: The raw 2D multichannel seismic reflection data in this project were acquired during expedition SO294 offshore Vancouver Island, Canada, using two different sources, i.e., a single GI Gun and a GGun array. The data were recorded with an 184-channel streamer. The objectives of expedition SO294 were twofold: provision of geophysical images to constrain the hazard potential of the Cascadia subduction zone, and to constrain the geophysical properties of the oceanic crust to assess its storage potential for carbon capture and storage (CCS). The data comprise 1660 line kilometers and are provided in raw format (SEG-D) and associated standardized metadata. Detailed information on the acquisition can be found in the SO294 cruise report (https://doi.org/10.48433/cr_so294). In addition, this technical report is provided with the 2D multichannel seismic reflection data set.

Description: The Falkland Shelf is a highly productive ecosystem in the Southwest Atlantic Ocean. It is characterized by upwelling oceanographic dynamics and displays a wasp-waist structure, with few intermediate trophic-level species and many top predators that migrate on the shelf for feeding. One of these resident intermediate trophic-level species, the Patagonian longfin-squid Doryteuthis gahi, is abundant and plays an important role in the ecosystem. We used two methods to estimate the trophic structure of the Falkland Shelf food web, focusing on the trophic niche of D. gahi and its impacts on other species and functional groups to highlight the importance of D. gahi in the ecosystem. First, stable isotope measurements served to calculate trophic levels based on an established nitrogen baseline. Second, an Ecopath model was built to corroborate trophic levels derived from stable isotopes and inform about trophic interactions of D. gahi with other functional groups. The results of both methods placed D. gahi in the centre of the ecosystem with a trophic level of ∼ 3. The Ecopath model predicted high impacts and therefore a high keystoneness for both seasonal cohorts of D. gahi. Our results show that the Falkland Shelf is not only controlled by species feeding at the top and the bottom of the trophic chain. The importance of species feeding at the third trophic level (e.g. D. gahi and Patagonotothen ramsayi) and observed architecture of energy flows confirm the ecosystem's wasp-waist structure with middle-out control mechanisms at play.

Description: Circulation anomalies accompanying Sudden Stratospheric Warmings (SSWs) can have a significant impact on the troposphere. This surface response is observed for some but not all SSWs, and their downward coupling is not fully understood. We use an existing classification method to separate downward- and non-propagating SSWs (d/nSSWs) in ERA5 reanalysis data for the years 1979–2019. The differences in SSW downward propagation in composites of spatial patterns clearly show that dSSWs dominate the surface regional impacts following SSWs. During dSSWs, the upper-tropospheric jet stream is significantly displaced equatorward. Wave activity analysis shows remarkable differences between d/nSSWs for planetary and synoptic-scale waves. Enhanced stratospheric planetary eddy kinetic energy (EKE) and heat fluxes around the central date of dSSWs are followed by increased synoptic-scale wave activity and even surface coupling for synoptic-scale EKE. An observed significant reduction in upper-tropospheric synoptic-scale momentum fluxes following dSSWs confirms the important role of tropospheric eddy feedbacks for coupling to the surface. Our findings emphasize the role of the lower stratosphere and synoptic-scale waves in coupling the SSW signal to the surface and agree with mechanisms suggested in earlier modeling studies.

Description: Monsoon systems transport water and energy across the globe, making them a central component of the global circulation system. Changes in different forcing parameters have the potential to fundamentally change the monsoon characteristics as indicated in various paleoclimatic records. Here, we use the Atmosphere Model developed at the Geo- physical Fluid Dynamics Laboratory (GFDL-AM2) and couple it with a slab ocean in order to analyze the monsoon’s sen- sitivity to changes in different parameters on a planet with idealized topography (varying land position, slab depth, atmospheric CO2 concentration, solar radiation, sulfate aerosol concentration, and surface albedo). This Monsoon Planet concept of an aquaplanet with a broad zonal land stripe allows us to reduce the influence of topography and to access the relevant meridional monsoon dynamics. In simulations with monsoon dynamics, a bimodal rainfall distribution develops during the monsoon months with one maximum over the tropical ocean and the other one over land. The intensity and ex- tent of the monsoon depend on the relative height of a local maximum in the surface pressure field that is acting as a bar- rier and is determining the coastward moisture transport. Changes in the barrier height occur during the course of one year but can also be induced when varying different parameters in the sensitivity analysis (e.g., the increase of atmospheric CO2 reduces the barrier height, resulting in an increase of rainfall, while aerosols have the opposing effect). This bimodal rainfall structure separated by a pressure barrier is also present in reanalysis data of the West African monsoon.

Description: Weather extremes are challenging the achievement of Sustainable Development Goal (SDG 2) – Zero Hunger globally and, most notably, in West Africa where it is further aggravated by rapid population growth. Here we present a stylized stochastic food production model to show how optimal crop allocations change depending on food security risk targets. To guarantee stable livelihoods for farmers, we examine the viability of a contingency fund that supports farmers in the event of low crop yields. Applied to the West African context, accounting for weather variability can substantially improve the reliability of the food supply and boost the fiscal sustainability of a contingency fund. Yet, setting reliability targets for food security is costly and leaves high residual risk in certain regions. Spatial risk-sharing through regional cooperation at the West African scale can eliminate the risk of insufficient food supply and further enhance the fund solvency.

Description: Rising seas are a threat to human and natural systems along coastlines. The relation between global warming and sea level rise is established, but the quantification of impacts of historical sea level rise on a global scale is largely absent. To foster such quantification, here we present a reconstruction of historical hourly (1979–2015) and monthly (1900–2015) coastal water levels and a corresponding counterfactual without long-term trends in sea level. The dataset pair allows for impact attribution studies that quantify the contribution of sea level rise to observed changes in coastal systems following the definition of the Intergovernmental Panel on Climate Change (IPCC). Impacts are ultimately caused by water levels that are relative to the local land height, which makes the inclusion of vertical land motion a necessary step. Also, many impacts are driven by sub-daily extreme water levels. To capture these aspects, the factual data combine reconstructed geocentric sea level on a monthly timescale since 1900, vertical land motion since 1900 and hourly storm-tide variations since 1979. The inclusion of observation-based vertical land motion brings the trends of the combined dataset closer to tide gauge records in most cases, but outliers remain. Daily maximum water levels get in closer agreement with tide gauges through the inclusion of intra-annual ocean density variations. The counterfactual data are derived from the factual data through subtraction of the quadratic trend. The dataset is made available openly through the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) at https://doi.org/10.48364/ISIMIP.749905 (Treu et al., 2023a).

Description: A potential shutdown of the Atlantic meridional overturning circulation (AMOC) is commonly recognised to have a significant impact on the Northern hemispheric climate, notably in Northern Europe. The collapse of the northbound heat transport by the AMOC is supposed to cool down surface air temperatures at the Scandinavian coast by up to 6 K accompanied by a concomitant nutrient starvation of phytoplankton in Subarctic and Arctic regions. However, besides local and regional impacts, tipping the AMOC into a weaker state by anthropogenic carbon dioxide (CO2) and associated freshwater forcing could also have surprising remote effects. In order to investigate possible long-term impacts of an AMOC shutdown on ocean biogeochemistry, we employ an Earth system model of intermediate complexity using idealised scenarios of century-scale atmospheric 2×CO2 and 4×CO2 pulses combined with North Atlantic freshwater forcing. The results show a continued increase in primary production, in particular in the Eastern equatorial Pacific, due to a decrease in iron limitation following the AMOC shutdown. Tracer simulations indicate that bioavailable dissolved iron brought by aeolian dust into the subtropical gyres of the Atlantic Ocean is transported to the Southern Ocean and from there enters the Indian Ocean and the Pacific. Thereby, the additionally introduced iron fertilises the phosphate-rich high-nutrient, low chlorophyll waters, giving a lasting boost to phytoplankton growth, especially in the Eastern equatorial Pacific.

Description: Im Kopernikus-Projekt Ariadne wurden zufällig ausgewählte Bürgerinnen und Bürger aus ganz Deutschland in einem Forschungs- und Lernprozess zur Verkehrs- und Stromwende beteiligt. Dieser Lernprozess eröffnete neue Begegnungs- und Reflexionsräume, in denen Forschende und Bürger:innen über verschiedene Politikoptionen zur Energie- und Verkehrswende diskutieren konnten.

Description: Ocean alkalinity enhancement (OAE) is considered one of the most promising approaches to actively remove carbon dioxide (CO2) from the atmosphere by accelerating the natural process of rock weathering. This approach involves introducing alkaline substances sourced from natural mineral deposits such as olivine, basalt, and carbonates or obtained from industrial waste products such as steel slags, into seawater and dispersing them over coastal areas. Some of these natural and industrial substances contain trace metals, which would be released into the oceans along with the alkalinity enhancement. The trace metals could serve as micronutrients for marine organisms at low concentrations, but could potentially become toxic at high concentrations, adversely affecting marine biota. To comprehensively assess the feasibility of OAE, it is crucial to understand how the phytoplankton, which forms the base of marine food webs, responds to ocean alkalinization and associated trace metal perturbations. In this study, we investigated the toxicity of nickel on three representative phytoplankton species across a range of Ni concentrations (from 0 to 100 µmol L-1 with 12 µmol L-1 synthetic organic ligand). The results showed that the growth of the tested species was impacted differently. The low growth inhibition and high IC50 (concentration to inhibit growth rate by 50 %) revealed that both the coccolithophore Emiliania huxleyi and the dinoflagellate Amphidinium carterae were mildly impacted by the increase in Ni concentrations while the rapid response to exposure of Ni, high growth rate inhibition, and low IC50 of Thalassiosira weissflogii indicate low tolerance to Ni in this species. In conclusion, the variability in phytoplankton sensitivity to Ni suggests that for OAE applications with Ni-rich materials caution is required and critical toxic thresholds for Ni must be avoided.

Description: The central Arctic Ocean (CAO) plays an important role in the global carbon cycle, but the current and future exchange of the climate-forcing trace gases methane (CH4) and carbon dioxide (CO2) between the CAO and the atmosphere is highly uncertain. In particular, there are very few observations of near-surface gas concentrations or direct air–sea CO2 flux estimates and no previously reported direct air–sea CH4 flux estimates from the CAO. Furthermore, the effect of sea ice on the exchange is not well understood. We present direct measurements of the air–sea flux of CH4 and CO2, as well as air–snow fluxes of CO2 in the summertime CAO north of 82.5∘ N from the Synoptic Arctic Survey (SAS) expedition carried out on the Swedish icebreaker Oden in 2021. Measurements of air–sea CH4 and CO2 flux were made using floating chambers deployed in leads accessed from sea ice and from the side of Oden, and air–snow fluxes were determined from chambers deployed on sea ice. Gas transfer velocities determined from fluxes and surface-water-dissolved gas concentrations exhibited a weaker wind speed dependence than existing parameterisations, with a median sea-ice lead gas transfer rate of 2.5 cm h−1 applicable over the observed 10 m wind speed range (1–11 m s−1). The average observed air–sea CO2 flux was −7.6 ..., and the average air–snow CO2 flux was −1.1 . Extrapolating these fluxes and the corresponding sea-ice concentrations gives an August and September flux for the CAO of −1.75 ... , within the range of previous indirect estimates. The average observed air–sea CH4 flux of 3.5 ..., accounting for sea-ice concentration, equates to an August and September CAO flux of 0.35 , lower than previous estimates and implying that the CAO is a very small (≪ 1 %) contributor to the Arctic flux of CH4 to the atmosphere.

Description: This study investigates the dynamics of magmatic intrusions based on the joint analysis of analog and numerical models. By injecting different fluids from the bottom of a solidified gelatin block, we simulate the propagation of magmatic intrusions through the crust and record their shapes, trajectories, and velocity as they rise towards the surface. Additionally, we make use of a 2D fluid-filled crack propagation model constrained by our experimental observations. The numerical simulations demonstrate that our viscous fluid-filled crack experiments, conducted with silicon-oil injections, propagate in the same regime as typical basaltic intrusions. The comparison between analog and numerical results allow us to define the domain of validity of the numerical model and its limit of applicability. This study provides new insights into the processes that control the propagation of magmatic intrusions and our ability to reproduce them using analog and numerical models.

Description: Identification of seismically active fault zones and the definition of sufficiently large respect distances from these faults which enable avoiding the damaged rock zone surrounding the ruptured ground commonly are amongst the first steps to take in the geoscientific evaluation of sites suitable for nuclear waste disposal. In this work we present a GIS-based approach, using the earthquake-epicentre locations from the instrumental earthquake record of South-Korea to identify potentially active fault zones in the country, and compare different strategies for fault zone buffer creation as originally developed for site search in the high seismicity country Japan, and the low-to-moderate seismicity countries Germany and Sweden. In order to characterize the hazard potential of the Korean fault zones, we moreover conducted slip tendency analysis, here for the first time covering the fault zones of the entire Korean Peninsula. For our analyses we used the geo-spatial information from a new version of the Geological map of South-Korea, containing the outlines of 11 rock units, which we simplified to distinguish between 4 different rock types (granites, metamorphic rocks, sedimentary rocks and igneous rocks) and the surface traces of 1,528 fault zones and 6,654 lineaments identified through years of field work and data processing, a rich geo-dataset which we will publish along with this manuscript. Our approach for identification of active fault zones was developed without prior knowledge of already known seismically active fault zones, and as a proof of concept the results later were compared to a map containing already identified active fault zones. The comparison revealed that our approach identified 16 of the 21 known seismically active faults and added 472 previously unknown potentially active faults. The 5 seismically active fault zones which were not identified by our approach are located in the NE- and SW-sectors of the Korean Peninsula, which haven’t seen much recent seismic activity, and thus are not sufficiently well covered by the seismic record. The strike directions of fault zones identified as active are in good agreement with the orientation of the current stress field of the peninsula and slip tendency analysis provided first insights into subsurface geometry such as the dip angles of both active and inactive fault zones. The results of our work are of major importance for the early-stage seismic hazard assessment that has to be conducted in support of the nuclear waste disposal siting in South-Korea. Moreover, the GIS-based methods for identification of active fault zones and buffering of respect areas around fault zone traces presented here, are applicable also elsewhere.

Description: Die Tarifparteien der Länder haben 2020 eine geänderte Entgeltordnung vereinbart, wodurch statt bibliotheksspezifischer nun die allgemeinen Tätigkeitsmerkmale für den Verwaltungsdienst auch auf Tätigkeiten in Bibliotheken angewendet werden. Dadurch sowie durch allgemeine aktuelle Entwicklungen im Bibliothekswesen ergeben sich in etlichen Entgeltgruppen Veränderungen. Das neue Standardwerk für die Erstellung von Stellenbeschreibungen und Stellenbewertungen in wissenschaftlichen Bibliotheken führt neben neuen auch umfassend aktualisierte Arbeitsvorgänge auf und versteht sich als Instrument, um Tätigkeiten in Bibliotheken den unbestimmten Rechtsbegriffen bzw. Entgeltgruppen der derzeit gültigen Entgeltordnung zuzuordnen. Ergänzt wird das Werk durch Grundlagenwissen zum Thema Eingruppierung, Stellenbeschreibung und Stellenbewertung. Nachdem Ende 2020 die Arbeitsvorgänge in Bibliotheken, 1. Öffentliche Bibliotheken (AVÖB) erschienen sind, folgt hiermit die Neufassung der Arbeitsvorgänge in wissenschaftlichen Bibliotheken (AVWB) sowie erstmals eine Zusammenstellung von Arbeitsvorgängen in staatlichen Bücherei- und Bibliotheksfachstellen (AVBF).

Description: Continental margins are a dynamic interface linking the terrestrial lithosphere and oceanic hydrosphere, thus controlling fluxes of terrigenous materials from land to ocean. In particular, estuaries are places channeling vast amounts of minerals, nutrients, organic matter and trace elements (TEs) in dissolved and particulate forms into the oceans. As many TEs are essential nutrients for phytoplankton growth, their concentrations ([TEs]) together with macronutrients in surface waters influence marine primary productivity, thereby impacting ocean ecosystems and carbon cycling. However, before entering the oceans, terrigenous TEs are modified at continental margins by various processes including removal, release and recycling. Consequently, studying geochemical cycling of TEs at continental margins is crucial for discerning their sources and processes that determine TE fluxes to oceans. Radiogenic neodymium (Nd) and hafnium (Hf) isotopic compositions, expressed as εNd and εHf, respectively are sensitive tracers of the origin and mixing of water masses and seawater-particle interactions at the continent-ocean interface. In this thesis a detailed investigation of the distributions of radiogenic Nd and Hf isotopes as well as rare earth elements and yttrium (REY) is performed across the Amazon freshwater plume, the Amazonian mangrove belt and the Amazon shelf and slope as part of the GEOTRACES GApr11 cruise. The objective is to investigate the sources and processes influencing the TE supplies, Nd and Hf isotope distributions and their fluxes to the western Atlantic Ocean.

Description: Human activities have had a significant impact on Earth's systems and processes, leading to a transition of Earth's state from the relatively stable Holocene epoch to the Anthropocene. The planetary boundaries framework characterizes major risks of destabilization, particularly in the core dimensions of climate and biosphere change. Land system change, including deforestation and urbanization, alters ecosystems and impacts the water and energy cycle between land surface and atmosphere, while climate change can disrupt the balance of ecosystems and impact vegetation composition and soil carbon pools. These drivers also interact with each other, further exacerbating their impacts. Earth system models have been used recently to illustrate the risks and interacting effects of transgressing selected planetary boundaries, but a detailed analysis is still missing. Here, we study the impacts of long-term transgressions of the climate and land system change boundaries on the Earth system using an Earth system model with an incorporated detailed dynamic vegetation model. In our centennial-scale simulation analysis, we find that transgressing the land system change boundary results in increases in global temperatures and aridity. Furthermore, this transgression is associated with a substantial loss of vegetation carbon, exceeding 200 PgC, in contrast to conditions considered safe. Concurrently, the influence of climate change becomes evident as temperatures surge by 2.7–3.1 °C depending on the region. Notably, carbon dynamics are most profoundly affected within the large carbon reservoirs of the boreal permafrost areas, where carbon emissions peak at 150 PgC. While a restoration scenario to reduce human pressure to meet the planetary boundaries of climate change and land system change proves beneficial for carbon pools and global mean temperature, a transgression of these boundaries could lead to profoundly negative effects on the Earth system and the terrestrial biosphere. Our results suggest that respecting both boundaries is essential for safeguarding Holocene-like planetary conditions that characterize a resilient Earth system and are in accordance with the goals of the Paris Climate Agreement.

Description: The problem of network disintegration, such as suppression of an epidemic spread and destabilization of terrorist networks, possesses extensive applications and has lately been the focus of growing interest. Many real-world complex systems are represented by spatial networks in which nodes and edges are spatially embedded. However, existing disintegration approaches for spatial network disintegration focus on singular aspects such as geospatial information or network topography, with insufficient modeling granularity. In this paper, we propose an effective and computationally efficient virtual node model that essentially integrates the geospatial information and topology of the network by modeling edges as virtual nodes with weights. Moreover, we employ Kernel Density Estimation, a well-known non-parametric technique for estimating the underlying probability density function of samples, to fit all nodes, comprising both network and virtual nodes, to identify the critical region of the spatial network, which is also the circular geographic region where disintegration occurs. Extensive numerical experiments on synthetic and real-world networks demonstrate that our method outperforms existing methods in terms of both effectiveness and efficiency, which provides a fresh perspective for modeling spatial networks.

Description: Investigating the correlations between time series is a fundamental approach to reveal the hidden mechanisms in complex systems. However, the estimated correlations often show time-dependent behaviors, which may create uncertainty for decision-making in various scenarios. Thus, forecasting the evolution of these varying correlations may be helpful, but it is still unsolved entirely. We bridge this gap by proposing a data-driven framework: (a) we first embed all the pairwise correlations within a complex system into multivariate correlation-based series by sliding windows; (b) we then identify two different low-dimensional representations of multivariate correlation-based series through delay embedding and dimensionality reduction; (c) finally, multistep ahead predictions of varying correlations can be achieved by training a mapping between two low-dimensional representations. Both model and real-world systems are used to illustrate our framework, including finance, neuroscience, and climate. Our framework is robust and has the potential to be used for other complex systems. Hopefully, forecasting the evolution of correlations in complex systems can be a useful complementary, since existing works mainly focus on the predictions of components within the systems.

Description: Crop models are essential tools for assessing the impact of climate change on national or regional agricultural production. Starting from meteorology, soil and crop management, fertilization and irrigation practices, they predict the yield of specific crop varieties. For long term assessments, climate models are the source of primary information. To make climate model results usable in a specific time frame context, bias adjustment (BA) is required. In fact, climate models tend to deviate from day-to-day values of the physical parameters while conserving the climate variability signal. BA brings the climatic signal to the actual values observed in a specific location and period, and to be representative of a specific period in absolute terms. BA techniques come in different flavours. The broadest categorization is univariate and multivariate methods. Multivariate methods adjust the variables considering possible cross-correlations while univariate methods treat the variables one by one without accounting for possible dependence on one another.

Description: The emergence of the evolutionary game on complex networks provides a fresh framework for studying cooperation behavior between complex populations. Numerous recent progress has been achieved in studying asymmetric games. However, there is still a substantial need to address how to flexibly express the individual asymmetric nature. In this paper, we employ mutual cognition among individuals to elucidate the asymmetry inherent in their interactions. Cognition arises from individuals’ subjective assessments and significantly influences their decision-making processes. In social networks, mutual cognition among individuals is a persistent phenomenon and frequently displays heterogeneity as the influence of their interactions. This unequal cognitive dynamic will, in turn, influence the interactions, culminating in asymmetric outcomes. To better illustrate the inter-individual cognition in asymmetric snowdrift games, the concept of favor value is introduced here. On this basis, the evolution of cognition and its relationship with asymmetry degree are defined. In our simulation, we investigate how game cost and the intensity of individual cognitive changes impact the cooperation frequency. Furthermore, the temporal evolution of individual cognition and its variation under different parameters was also examined. The simulation results reveal that the emergence of heterogeneous cognition effectively addresses social dilemmas, with asymmetric interactions among individuals enhancing the propensity for cooperative choices. It is noteworthy that distinctions exist in the rules governing cooperation and cognitive evolution between regular networks and Watts–Strogatz small-world networks. In light of this, we deduce the relationship between cognition evolution and cooperative behavior in co-evolution and explore potential factors influencing cooperation within the system.

Description: We study three different strategies of vaccination in an SEIRS (Susceptible–Exposed–Infected–Recovered–Susceptible) seasonal forced model, which are (⁠ ⁠) continuous vaccination; (⁠ ⁠) periodic short-time localized vaccination, and (⁠ ⁠) periodic pulsed width campaign. Considering the first strategy, we obtain an expression for the basic reproduction number and infer a minimum vaccination rate necessary to ensure the stability of the disease-free equilibrium (DFE) solution. In the second strategy, short duration pulses are added to a constant baseline vaccination rate. The pulse is applied according to the seasonal forcing phases. The best outcome is obtained by locating intensive immunization at inflection of the transmissivity curve. Therefore, a vaccination rate of of susceptible individuals is enough to ensure DFE. For the third vaccination proposal, additionally to the amplitude, the pulses have a prolonged time width. We obtain a non-linear relationship between vaccination rates and the duration of the campaign. Our simulations show that the baseline rates, as well as the pulse duration, can substantially improve the vaccination campaign effectiveness. These findings are in agreement with our analytical expression. We show a relationship between the vaccination parameters and the accumulated number of infected individuals, over the years, and show the relevance of the immunization campaign annual reaching for controlling the infection spreading. Regarding the dynamical behavior of the model, our simulations show that chaotic and periodic solutions as well as bi-stable regions depend on the vaccination parameters range.

Description: Operating within safe and just Earth system boundaries requires mobilizing key actors across scale to set targets and take actions accordingly. Robust, transparent and fair cross-scale translation methods are essential to help navigate through the multiple steps of scientific and normative judgements in translation, with clear awareness of associated assumptions, bias and uncertainties. Here, through literature review and expert elicitation, we identify commonly used sharing approaches, illustrate ten principles of translation and present a protocol involving key building blocks and control steps in translation. We pay particular attention to businesses and cities, two understudied but critical actors to bring on board.

Description: Oscillatory instability emerges amidst turbulent states in experiments in various turbulent fluid and thermo-fluid systems such as aero-acoustic, thermoacoustic and aeroelastic systems. For the time series of the relevant dynamic variable at the onset of the oscillatory instability, universal scaling behaviors have been discovered in experiments via the Hurst exponent and certain spectral measures. By means of a center manifold reduction, the spatiotemporal dynamics of these real systems can be mapped to a complex Ginzburg–Landau equation with a linear global coupling. In this work, we show that this model is able to capture the universal behaviors of the route to oscillatory instability, elucidating it as a transition from defect to phase turbulence mediated by the global coupling.

Description: Crop models are often used to project future crop yield under climate and global change and typically show a broad range of outcomes. To understand differences in modeled responses, we analysed modeled crop yield response types using impact response surfaces along four drivers of crop yield: carbon dioxide (C), temperature (T), water (W), and nitrogen (N). Crop yield response types help to understand differences in simulated responses per driver and their combinations rather than aggregated changes in yields as the result of simultaneous changes in various drivers. We find that models’ sensitivities to the individual drivers are substantially different and often more different across models than across regions. There is some agreement across models with respect to the spatial patterns of response types but strong differences in the distribution of response types across models and their configurations suggests that models need to undergo further scrutiny. We suggest establishing standards in model evaluation based on emergent functionality not only against historical yield observations but also against dedicated experiments across different drivers to analyze emergent functional patterns of crop models.

Description: Flood losses have steadily increased in the past and are expected to grow even further owing to climate and socioeconomic change. The reduction of flood vulnerability, for example, through adaptation, plays a key role in the mitigation of future flood risk. However, lacking knowledge about vulnerability dynamics, which arise from the interaction between floods and the ensuing response by society, limits the scope of current risk projections. We present a socio-hydrological method for flood risk assessment that simulates the interaction between society and flooding continuously, including changes in vulnerability through collective (structural) and private (non structural) measures. Our probabilistic approach quantifies uncertainties and exploits empirical data to chart risk dynamics including how society copes with flooding. In a case study for the commercial sector in Dresden, Germany, we show that increased adaptation is necessary to counteract the expected four-fold growth in flood risk due to transient hydroclimatic and socioeconomic boundary conditions. We further use our holistic approach to identify solutions for effective long-term adaptation, demonstrating that integrated adaptation strategies (i.e., combined structural and non structural measures) can reduce the average risk by up to 60% at the study site. Ultimately, our case study highlights the benefit of the model for robust flood risk assessment as it can capture unintended, adverse feedbacks of adaptation measures such as the levee effect. Consequently, our socio-hydrological method contributes to a more systemic and reliable flood risk assessment that can inform adaptation planning by exploring the possible system evolutions comprehensively including unlikely futures.

Description: In this study, the distribution characteristics, seasonal variations, sea-to-air fluxes, and influencing factors of CO in the Ria Formosa Lagoon system and at Boknis Eck time-series station were systematically investigated through a combination of situ measurements and incubation experiments. The relationship between CO and physical-chemical-biological factors and the potential impact of aquaculture activities were explored. The contribution of the study areas to regional or global atmospheric CO and the various sources and removal rates of CO were quantified. Factors affecting the source-sink pathway were investigated, and the source-sink balance of CO within the surface layer was quantitatively assessed. In addition, a comprehensive compilation of 〉12,000 sea-surface CO observations was performed to reconstruct oceanic emissions using a data-driven machine learning approach, reducing the estimation uncertainty of global oceanic emissions of CO. This thesis work can provide a solid scientific foundation for establishing a biogeochemical cycle model of CO in the ocean.

Description: What action should we take for the effective mitigation of climate change? Measures to avoid greenhouse gas emissions are surely the main priority – but the truth is that in the coming decades, we will also have to remove large quantities of carbon dioxide from the atmosphere and store it securely. Can – indeed, should – the ocean aid us in this task? The new World Ocean Review (WOR 8) explores this issue with reference to the oceans' role in the Earth's carbon cycle and looks at the benefits, risks and knowledge gaps around the main marine carbon dioxide removal techniques.

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: Interest in deep-sea mining for polymetallic nodules as an alternative source to onshore mines for various high-technology metals has risen in recent years, as demands and costs have increased. The need for studies to assess its short- and long-term consequences on polymetallic nodule ecosystems is therefore also increasingly prescient. Recent image-based expedition studies have described the temporal impacts on epi-/megafauna seafloor communities across these ecosystems at particular points in time. However, these studies have failed to capture information on large infauna within the sediments or give information on potential transient and temporally limited users of these areas, such as mobile surface deposit feeders or fauna responding to bloom events or food fall depositions. This study uses data from the Peru Basin polymetallic nodule province, where the seafloor was previously disturbed with a plough harrow in 1989 and with an epibenthic sled (EBS) in 2015, to simulate two contrasting possible impact forms of mining disturbance. To try and address the shortfall on information on transient epifauna and infauna use of these various disturbed and undisturbed areas of nodule-rich seafloor, images collected 6 months after the 2015 disturbance event were inspected and all Lebensspuren, 'traces of life', were characterized by type (epi- or infauna tracemakers, as well as forming fauna species where possible), along with whether they occurred on undisturbed seafloor or regions disturbed in 1989 or 2015. The results show that epi- and endobenthic Lebensspuren were at least 50% less abundant across both the ploughed and EBS disturbed seafloors. This indicates that even 26 years after disturbance, sediment use by fauna may remain depressed across these areas.

Description: Photosynthesis fuels primary production at the base of marine food webs. Yet, in many surface ocean ecosystems, diel-driven primary production is tightly coupled to daily loss. This tight coupling raises the question: which top-down drivers predominate in maintaining persistently stable picocyanobacterial populations over longer time scales? Motivated by high-frequency surface water measurements taken in the North Pacific Subtropical Gyre (NPSG), we developed multitrophic models to investigate bottom-up and top-down mechanisms underlying the balanced control of Prochlorococcus populations. We find that incorporating photosynthetic growth with viral- and predator-induced mortality is sufficient to recapitulate daily oscillations of Prochlorococcus abundances with baseline community abundances. In doing so, we infer that grazers in this environment function as the predominant top-down factor despite high standing viral particle densities. The model-data fits also reveal the ecological relevance of light-dependent viral traits and non-canonical factors to cellular loss. Finally, we leverage sensitivity analyses to demonstrate how variation in life history traits across distinct oceanic contexts, including variation in viral adsorption and grazer clearance rates, can transform the quantitative and even qualitative importance of top-down controls in shaping Prochlorococcus population dynamics.

Description: The potential for future earthquakes on faults is often inferred from inversions of geodetically derived surface velocities for locking on faults using kinematic models such as block models. This can be challenging in complex deforming zones with many closely spaced faults or where deformation is not readily described with block motions. Furthermore, surface strain rates are more directly related to coupling on faults than surface velocities. We present a methodology for estimating slip deficit rate directly from strain rate and apply it to New Zealand for the purpose of incorporating geodetic data in the 2022 revision of the New Zealand National Seismic Hazard Model. The strain rate inversions imply slightly higher slip deficit rates than the preferred geologic slip rates on sections of the major strike‐slip systems including the Alpine Fault, the Marlborough Fault System and the northern part of the North Island Fault System. Slip deficit rates are significantly lower than even the lowest geologic estimates on some strike‐slip faults in the southern North Island Fault System near Wellington. Over the entire plate boundary, geodetic slip deficit rates are systematically higher than geologic slip rates for faults slipping less than one mm/yr but lower on average for faults with slip rates between about 5 and 25 mm/yr. We show that 70%–80% of the total strain rate field can be attributed to elastic strain due to fault coupling. The remaining 20%–30% shows systematic spatial patterns of strain rate style that is often consistent with local geologic style of faulting. Plain Language Summary The potential for future earthquakes on faults is often inferred from velocities of the ground surface derived from satellite geodesy, but this approach can be challenging in complex deforming zones with many closely spaced faults. We present a new methodology for estimating the rate at which energy is accumulating on faults using measurements of surface strain rates. The method is applied to New Zealand for the purpose of incorporating geodetic data in the 2022 revision of the New Zealand National Seismic Hazard Model. We show that 70%–80% of the total deformation field can be attributed to energy accumulation on known active faults while the source of the remaining 20%–30% remains unknown. Along some of the major faults in New Zealand we find some important differences in rates of energy accumulation from what is expected from geologic data. Estimated rates are significantly lower than even the lowest geologic estimates on some faults in the fault system near highly‐populated Wellington. Key Points We develop a method to invert geodetically derived strain rates for slip deficit rates on faults We find small but systematic differences between slip deficit rates and geologic slip rates About 70%–80% of the surface strain can be attributed to elastic strain due to coupling on faults

Description: Nutrient transfer into the sunlit surface ocean by cyclonic eddies is potentially crucial for sustaining primary productivity in the stratified subtropical gyres. However, the nature of productivity enhancements, including the flow of matter to higher trophic levels and its impact on carbon fluxes, remain poorly resolved. Here, we report a detailed assessment of the biogeochemical response to a cyclonic eddy in the subtropical Northwest Pacific via a combination of ship‐based and autonomous platforms. Primary production was enhanced twofold within the eddy core relative to reference sites outside, whereas phytoplankton biomass even decreased. Pico‐phytoplankton (〈 2 μ m) dominated (〉 80%) both phytoplankton biomass and primary production inside and outside the eddy. The stimulated primary production in the eddy core was accompanied by an approximately twofold increase in mesozooplankton abundance, an approximately threefold increase in particle formation in the deep chlorophyll maximum layer, as well as significantly enhanced surface oceanic CO 2 uptake and net community production. We suggest these observations carry important implications for understanding carbon export in the subtropical ocean and highlight the need to include such subtropical eddy features in ocean carbon budget analyses.