bluuebunny/crossref_metadata_2025 huggingface dataset:
Increasing fluvial incision rate in the southern Jinshan Gorge from tributary terraces and river network analysis
Authors: Zhong Yuezhi , Picotti Vincenzo , Xiong Jianguo , Willett Sean , Schmidt Christoph , King Georgina
Published: March 2024

Base level fall on a tributary is genetically related to its trunk channel incision, and analysis of tributaries thus provides information of the trunk channel evolution history. In the middle Yellow River, for example, several integration processes were proposed and should be consistent with river terrace data from the trunk channel. We investigate the rates and spatiotemporal variations of incision along the Jinshan Gorge in the middle Yellow River with dated strath terraces from its tributaries. The incision rate for six tributaries along the Jinshan Gorge is constrained using mapped and dated terraces. By comparing terraces of similar age, we find generally decreasing incision rates from the confluence with the trunk river to upstream within a tributary in the southern Jinshan Gorge. Decreasing incision rates are also observed among tributaries from south to north along the gorge. The results independently confirm the spatial pattern from “pseudo-terraces” derived from channel profile modeling. This interpretation reinforces the previous proposal that paleo-lake regressions in the Weihe Graben or integration with the Hetao Graben are unlikely to have been responsible for recent incision. An estimation method with terrace data within a tributary of erodibility coefficient, K, a crucial parameter for river profile inversion analysis, is also provided. K is recalibrated to be 1.03 10-5 m0.3/a with all terrace data. With an assemblage of published terrace data along the Jinshan Gorge, we suggest a re-examination of published terrace ages, which may help unravel the mysterious evolution history of the middle Yellow River.
Reactivation of caldera structures in active extensional settings: implication for geothermal exploration
Authors: Maestrelli Daniele , Corti Giacomo , Bonini Marco , Keir Derek , Trumpy Eugenio , Facincani Pietro , Vannucchi Paola , Del Ventisette Chiara , Montanari Domenico , Sani Federico
Published: March 2024

Collapsed calderas are prominent volcano-tectonic features occurring in active tectonic settings and bear intrinsic risks associated with their explosiveness. Nonetheless, they also represent key targets for geothermal fluid exploration, their structures being often the preferential pathway for geothermal fluids migration. In active tectonic settings such as continental rifts, caldera faults may be reactivated, enhancing therefore their permeability. However, specific structures may be subject to clamping, consequently reducing their secondary porosity. Discriminating if and how caldera structures may respond to tectonic stresses, represents therefore a critical question to address when calderas become the locus of potential geothermal exploration. We performed an experimental series of analogue models of caldera collapse exploring whether caldera structures may reactivate under extensional tectonic conditions. This analysis is important for evaluating which caldera fault segments may be regarded as the best potential target for fluid interception. Our experimental series shows that regional extension and fault dip can explain the reactivation of specific caldera fault segments. In particular, outer normal ring faults do reactivate under extensional conditions only in the sectors trending orthogonally to the direction of extension. Conversely, inner outward-dipping reverse faults do not reactivate, likely because of their lower dip angle, whichever their trend might be. This implies that inward-dipping normal faults trending orthogonal to direction of extension likely increase their permeability, thus becoming a favourable locus for geothermal fluid migration and therefore a preferable target for exploration. Conversely, our models show that sectors of inward-dipping normal caldera faults trending parallel to the direction of extension may experience clamping, and so reducing their secondary permeability. Therefore, our setup, with due approximations and limitations, represents a useful predictive tool for identifying potential target structures for geothermal exploration at caldera sites. The model setup can also provide insights into similar caldera systems developing in other geological settings (e.g., compressional).
Teasing apart the role of late Pleistocene human arrival and megafauna extinction on Amazonian tree composition
Authors: van der Sande Masha , Raczka Marco , Onstein Renske , Poorter Lourens , Rabbi Md Golam , Sheil Douglas , de Oliveira Paulo , Peña-Claros Marielos
Published: March 2024

At the end of the Pleistocene, tropical forests in South America underwent three drastic changes that are analogous to today: the climate warmed, people populated the region and started to use and domesticate of part of the native forest plants, and the abundance of seed-dispersing megafauna collapsed. Here, we evaluate the impact of these three changes on tree populations in South America, using pollen time series of >80 tree and palm genera across 10 sites collected over a 100,000 yr period spanning the end of the Pleistocene and Holocene, and linking this to genus-specific traits that are indicators of climate responses, usefulness to humans, and dispersal by megafauna. We find no support for consistent effects of climate warming, and find that megafauna-dispersed tree genera increased – instead of decreased – in abundance after megafauna decline, indicating that climate warming and megafauna decline were no major drivers of changes in tree populations. However, we find that edible tree and palm species increased in abundance. These results are consistent with the idea that people favoured tree taxa that were useful for consumption of their large seeds and fruits, and in this way took over the role of lost seed dispersers and artificially increased the abundance of previously megafauna-dispersed tree taxa.
Estimates of the dissolved organic carbon concertation from remote sensing in the frame of the OCROC project.
Authors: Montero Marie , Loisel Hubert , Jorge Daniel S.F , Bretagnon Marine , Demaria Julien , Prat Aurélien , Bonelli Ana Gabriela , Duforêt-Gaurier Lucile , Mangin Antoine
Published: March 2024

Carbon monitoring from space is critical for the reporting and verification of carbon stocks and changes in both coastal and open ocean waters. In the frame of the OCROC project, funded by the Copernicus 2 – 1st Service Evolution Call for Tenders (2022-2024), we focus on the particulate (POC) and dissolved (DOC) organic carbon of surface oceanic and coastal waters, which represent the two components of the total organic carbon (TOC) pool in the ocean. The present presentation is mainly dedicated to the estimation of DOC, the main contributor to TOC, over open ocean waters. An enhanced version of the Ocean and Land Color Instrument's (OLCI) DOC algorithm of Bonelli et al. (2022) is presented and adapted to historical and present ocean color sensors. This algorithm employs two different Artificial Neural Network (ANN) algorithms depending on the Optical Water Classes, and four input parameters namely the absorption coefficient of Colored Dissolved Organic Matter (acdom(443)) chlorophyll-a concentration (Chl-α),  Sea Surface Temperature (SST), and Mixed Layer Depth (MLD). In this new version of the algorithm SST and MLD are both delivered by COPERNICUS (Multi Observation Global Ocean ARMOR3D L4 analysis and multi-year reprocessing).  Each of the four input parameters is provided at a distinct time lag to enhance the accuracy of the model. Furthermore, a revisited “match-up” database, compared to the one used in Bonelli et al. (2022), is utilized to validate the algorithm across multiple ocean color missions.
Spectral Analysis of High-Energy Radiation Events Observed during the ALOFT 2023 Campaign
Authors: Sarria David , Østgaard Nikolai , Marisaldi Martino , Lang Timothy , Grove Eric , Quick Mason , Christian Hugh , Schultz Chris , Blakeslee Richard , Adams Ian , Kroodsma Rachael , Heymsfield Gerald , Mezentsev Andrey , Bjørg Engeland Ingrid , Fuglestad Anders , Lehtinen Nikolai , Ullaland Kjetil , Yang Shiming , Hasan Quresh Bilal , Søndergaard Jens ,   ALOFT Team
Published: March 2024

The Airborne Lighting Observatory for FEGS and TGFs (ALOFT) is equipped with a comprehensive set of instruments on-board a NASA ER-2 research aircraft for observing Terrestrial Gamma-ray Flashes (TGFs) and gamma-ray glows from thunderclouds. The ER-2 research aircraft flew at about 20 km altitude, above thunderstorms, from July 1st to July 30th, 2023, for a total flight time of about 60 hours.  The onboard instrument suite comprised several X/gamma-ray detectors, which spanned a dynamic range of four orders of magnitude in flux and covered the entire energy spectrum associated with the gamma-ray transients.    During the campaign, we observed over 130 short gamma-ray transients, along with hundreds of gamma-ray glows. Several of these detections consisted of thousands of photon counts, allowing precise and unprecedented spectral analyses.    In this study, we present a comprehensive spectral analysis of various events using a forward modeling technique and Monte-Carlo simulations. This approach enables us to constrain the source characteristics of these events, including their source energy spectrum, production altitude and offset, spatial extension, and the brightness (fluence) of the source RREA electrons.
Detection and Characterization of Climate Extremes with Deep Learning
Authors: Durif Anne , Pagé Christian
Published: March 2024

Over the past few years, the consequences of climate extremes have become increasingly concerning. According to IPCC projections (Intergovernmental Panel on Climate Change), such events are to keep increasing in frequency, intensity, and duration. We aim at characterizing those changes, depending on carbon emission scenarios. But the analysis of climate simulations requires a huge computational power: data are available at a daily frequency, at a global scale at a ~125km spatial resolution, and depend on each realization of different climate models and scenarios.We propose a novel method, a deep learning model, to address such big geospatial data sets. The state of the art for climate extreme detection with Artificial Intelligence focuses on satellite imagery, past events, or short-term forecasting. It is less prolific for future events or simultaneous analysis of several climate models and scenarios. In 2020, Sinha et al. developed an anomaly detection model to spot avalanches in satellite images. She tackled the same issue as ours: an unsupervised anomaly detection problem, with numerous unlabeled pictures of both normal snow surfaces and avalanche deposits.The algorithm is based on a Convolutional Variational AutoEncoder (CVAE), a Neural Network that learns in an unsupervised setup. It is fed with plenty of images, with a small proportion of abnormal images, and learns how to compress and reconstruct them. The network has no information about whether the image is an anomaly or not. At the end of the training phase, it does a good job reconstructing normal images, but it struggles (high reconstruction error) with unusual samples.In our case, the model is trained for each season on observations of a specific climate variable (e.g. temperature), on a given geographical zone. It is then applied to projection data (IPCC scenarios) on the same variable for the same location. The output images and losses are then post-processed as time series to extract statistical characterizations of the events, such as their frequency, intensity, or duration. The results are validated with several members (realizations) of the same climate model, and compared with analytical indices over a historical sample.This work was supported by InterTwin project. InterTwin is funded by the European Union (Horizon Europe) under grant agreement No 101058386.
Cover Crops Affect Pool Specific Soil Organic Carbon in Cropland – a Meta-analysis
Authors: Fohrafellner Julia , Keiblinger Katharina , Zechmeister-Boltenstern Sophie , Murugan Rajasekaran , Spiegel Heide , Valkama Elena
Published: March 2024

Cover crops (CC) offer numerous benefits to agroecosystems, particularly in the realm of soil organic carbon (SOC) accrual and loss mitigation. However, uncertainties persist regarding the extent to which CCs, in co-occurrence with environmental factors, influence SOC responses and associated C pools. We therefore performed a weighted meta-analysis on the effects of CCs on the mineral associated organic carbon (MAOC), the particulate organic carbon (POC) and the microbial biomass carbon (MBC) pool in arable cropland. Our study summarized global research of comparable management, with a focus on climatic zones representative of Europe, such as arid, temperate and boreal climates.     In this meta-analysis, we included 71 independent studies from 61 articles published between 1990 and June 2023 in several scientific and grey literature databases. Sensitivity analysis was conducted and did not identify any significant publication bias. The results revealed that CCs had an overall statistically significant positive effect on SOC pools, increasing MAOC by 4.8% (CI: 0.6% - 9.4%, n = 16), POC by 23.2% (CI: 13.9% - 34.4%, n = 39) and MBC by 20.2% (CI: 11.7% - 30.7%, n = 30) in the top soil, compared to no CC cultivation. Thereby, CCs feed into the stable as well as the more labile C pools. The effect of CCs on MAOC was dependent on soil clay content and initial SOC concentration, whereas POC was influenced by moderators such as CC peak biomass and experiment duration. For MBC, e.g., clay content, crop rotation duration and tillage depth were identified as important drivers.     Based on our results on the effects of CCs on SOC pools and significant moderators, we identified several research needs. A pressing need for additional experiments exploring the effects on CCs on SOC pools was found, with a particular focus on MAOC and POC. Further, we emphasize the necessity for conducting European studies spanning the north-south gradient.     In conclusion, our results show that CC cultivation is a key strategy to promote C accrual in different SOC pools. Additionally, this meta-analysis provides new insights on the state of knowledge regarding SOC pool changes influenced by CCs, offering quantitative summary results and shedding light on the sources of heterogeneity affecting these findings.
A global inventory of shelf sea carbon
Authors: Ward Sophie , Scourse James , Roseby Zoe , Bradley Sarah
Published: March 2024

The ocean is known to be a vast and globally important carbon sink and there is an urgent need to better understand the role played by shelf sea sediments in the ocean carbon cycle. Organic carbon is preferentially stored in marine muds, the deposition of which has predominantly been dictated by bottom currents controlled by waves and tides. Through numerical modelling to predict carbon accumulation, alongside data mining and synthesis, we aim to make a first-order approximation of global carbon stocks in shelf sea sediments. We are developing new high resolution numerical models to simulate the timing and distribution of carbon-rich mud accumulations across global shelf seas. These models will reconstruct current flows near the seabed driven by the tides and waves, for the period since the Last Glacial Maximum (approximately 22,000 years ago). We incorporate dynamic palaeo-topographies from the latest regional glacial isostatic adjustment models, as well as adopting the novel approach of palaeo-wave modelling (forced by palaeo-wind datasets). The simulated hydrodynamics will be used to estimate where accumulation of fine sediments may occur on shelf seas. These synthetic maps of fine sediment deposits will be constrained and validated using observational data from sediment samples (e.g., data on sediment grain size and carbon content). Radiocarbon age-constrained samples from shelf sea sediment cores will then be used to test the validity of the model predictions for estimating accumulations of carbon-rich sediments over thousands of years. As this work considers potential mud accumulation – and carbon stocks - within muddy basin fills, it builds upon existing works which to date have primarily focused on surface sediment. This novel global inventory of shelf sea carbon stocks will inform global carbon budgets and protection- and restoration efforts of these globally significant blue carbon stocks.
Potential metal(loid)s mobilization from acid mine drainage-affected sediments under sea level rise projections
Authors: Basallote María Dolores , Miranda Rona Giese , Frank Martin , Olías Manuel , Cánovas Carlos Ruiz
Published: March 2024

Metals and metalloids are among the most dispersed hazardous substances released to estuarine systems, which often accumulate within the sediments, contributing to a global problem of pollution in estuaries. In this context, the projected future sea level rise predict the inundation of metal-polluted sediments in littoral areas, which may have serious implications in the mobility of sediment-bound contaminants.The Tinto River estuary (SW Spain), which is projected to be partially flooded by seawater in 2050 due to the rising sea level, have historically received significant amounts of potentially toxic elements originating from former metal mines, transported to the estuary by the Tinto River.To estimate the potential release of metal(loid)s associated with seawater flooding, surface sediments were sampled to determine metal concentrations, total carbon content, pH, and particle size distribution. In addition, the contamination factor, geoaccumulation index, and pollution load index were calculated to evaluate metal(loid) pollution. To estimate metal(loid) mobilization upon sea level rise a delimited area of the Tinto River estuary was defined (according to sea level rise projections), and elements mobilization was calculated using values obtained from inundation experiments (Kerl et al., 2023) and sequential extraction methods.Sediments from the study site turn out to be highly polluted with calculated pollution load indices over 1 and surpassing Spanish guidelines and international sediment quality guidelines , especially for As (300 – 1300 mg/kg), Cu (300 – 3500 mg/kg) and to a lesser extent Zn (100 – 1400 mg/kg) and Cd (0.2 – 5.8 mg/kg). Results show that significant amounts of Fe, Cu, Zn and As (36800, 11200, 1390, 3.22 kg, respectively) can be mobilized under short-term inundations (65 days) related to climate change scenarios predicted for 2050. Under 2100 projections, the mobilization of those metal(loid)s is expected to be further enhanced by the additonal release of large amounts of Fe, as a result of the reductive dissolution of Fe- or Mn-oxyhydroxides, which is mainly attributed to the promotion of reduced conditions in currently oxic sediment layers. These results provide a first estimation of the potential mobilization of potentially toxic elements upon climate change, which is of paramount importance for risk assessment in metal(loid) polluted estuaries worldwide.
Global patterns of Mediterranean ecosystems recovery from recurrent fires
Authors: Ermitão Tiago , Gouveia Célia , Bastos Ana , Russo Ana
Published: March 2024

Over the past two decades wildfires have been increasingly disturbing many ecosystems worldwide. Among them, the Mediterranean-like climate regions have been strongly affected by recurrent events, as widely seen during the fire seasons of 2003, 2005, 2017 and 2022 in Portugal and northern Spain, as well as in Greece and southern Italy in 2007, 2021 and 2023. Additionally, Chile experienced significant fire seasons in 2015 and 2017, California faced destructive wildfires in 2018, 2020 and 2021, and Australia was affected by severe wildfires during 2019-2020.Even though there is an observed increase of fire frequency over fire-prone regions, the Mediterranean ecosystems are in general well adapted to fire through several mechanisms to tolerate exposure to extreme conditions and recover from fire. However, climate change has been exacerbating the frequency and severity of climate extreme events, so that the pace of recovery of ecosystems from fires may be impaired, enhancing the potential of irreversible changes in vegetation communities. Here we assess the recovery of global Mediterranean vegetation after recurrent fires over the past two decades based on Enhanced Vegetation Index (EVI) retrieved from the MODIS sensor. To do so, we apply a statistical model to assess the recovery rate of vegetation repeatedly burned across different land cover types. Moreover, we study how fire severity, pre-fire state of vegetation and post-fire climate conditions modulate the recovery rates. Our results show a significant influence of fire severity on vegetation recovery rates globally across all Mediterranean regions, suggesting that higher severity levels may trigger the activation of the ecosystem's recovery mechanisms. Nevertheless, we also find a modulating effect of post-fire climate conditions, particularly air temperature and precipitation, on the recovery rates of burned vegetation, which highlights how compounding effects of changing disturbance regimes and climate change might destabilize ecosystems.This study was supported by the doctoral Grant PRT/BD/154296/2022 financed by FCT under the MIT Portugal Program and was performed under the framework of DHEFEUS project, funded by Portuguese Fundação para a Ciência e a Tecnologia (FCT) (https://doi.org/10.54499/2022.09185.PTDC). The work was also funded by the FCT I.P./MCTES through national funds (PIDDAC) UIDB/50019/2020 (https://doi.org/10.54499/UIDB/50019/2020), UIDP/50019/2020 (https://doi.org/10.54499/UIDP/50019/2020) and LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020). A.R. is supported by the FCT through national funds from the MCTES within the Faculty of Sciences of University of Lisbon, through https://doi.org/10.54499/2022.01167.CEECIND/CP1722/CT0006.
Rock magnetic record of environmental changes over the last 40.000 years in the Westermost Mediterranean: the Alboran Sea sedimentary record
Authors: Villasante Marcos Victor , Beltrán de Heredia García-Nieto Silvia , Martínez Ruiz Francisca , Casanova Arenillas Santiago , Rodríguez Tovar Francisco Javier
Published: March 2024

We present here a high-resolution rock magnetic study of deep-sea marine sediments from the Alboran Sea (Westernmost Mediterranean). The analyzed sediment  record, core GP03, 889 cm in length, covers the last 40.000 years from upper Pleistocene glacial times through the Last Glacial Maximum, subsequent deglaciation, Younger Dryas cooling reversal and the whole Holocene up to the current Industrial Period. The sediment core was sampled at high resolution, and 379 samples were measured for their bulk magnetic susceptibility, frequency-dependent susceptibility, hysteresis cycles and Isothermal Remanent Magnetization (IRM) direct and reverse acquisition curves. A subset of 125 samples were subjected to thermomagnetic experiments up to 700º C in order to reveal Curie and thermal transformation temperatures and to support the identification of the precise magnetic mineralogy. The variations in the magnetic mineralogy along the analyzed record, together with previously published geochemical data, have allowed to track the main paleoenvironmental and paleoclimatic changes in the studied region over the last 38 ka, as well as documenting a very strong reductive dissolution horizon affecting magnetic phases in the Younger Dryas sediments, which points to a significant deoxygenation event. A strong correlation of magnetic parameters and stadial-interstadial fluctuations during the last glaciation, especially between 25 and 38 ka, is observed, pointing to variations in riverine vs. aeolian terrigenous input. In modern sediments (approximately the last 200 years), a sharp increase in magnetite abundance in the sediments has been recognized, coinciding with the timespan of the Industrial Period. We conducted magnetic extraction to concentrate the ferromagnetic fraction of these sediments, followed by Scanning Electron Microscopy and EDS analysis, and identified strongly ferromagnetic microspherules with textures typical of rapid crystallization from high temperature melts. These microspherules, rich in magnetite, are indistinguishable from typical fly ash magnetic microspherules of industrial origin, which support they are the magnetic fingerprint of anthropogenic industrial ferromagnetic phases in this marine setting that superimposed on the natural paleoenvironmental changes during the uppermost Pleistocene and Holocene.
How to make droughts newsworthy: lessons from the 2022/2023 snow deficit in the Italian Alps
Authors: Avanzi Francesco , Mantini Marina , Marighella Annalisa , Porcu Silvia , Romano Anna , Salvioli Mariani Luca , Caporlingua Marina , Finizio Michela , Galimberti Luca , Cotugno Ferdinando , Grazzini Federico , Lozito Nicolas , Breeze Nick , Cremonese Edoardo , Galvagno Marta , Favre Sara , Pogliotti Paolo , Morra di Cella Umberto , Rossi Lauro , Ferraris Luca
Published: March 2024

Winter 2021-2022 and 2022-2023 were characterized by extreme drought conditions across the Italian Alps, with a –60% in Snow Water Equivalent at peak accumulation compared to recent years. During summer 2022, this deficit in snow compounded the ongoing precipitation deficit and temperature anomaly in dictating historical lows in water supply across the Po river basin. In this context, in January 2022 CIMA Research Foundation initiated periodic communication actions on social media and its website (https://www.cimafoundation.org/en/) to report on the ongoing snow-drought conditions and the potential implications for water security. This effort started from dissemination on social media, such as threads on Twitter/X (https://twitter.com/CIMAFoundation/status/1646451722968088577) and on LinkedIn, and ended up in triggering a significant media coverage in the form of national/international newspapers, all-news TV outlets, blogs, podcasts, and official reports at various levels. The communication became a campaign that influenced drought storytelling in Italy, creating an unexpected “snowball effect”. In this case study, CIMA’s researchers got together with some of the journalists and science communicators who covered this event to discuss reasons for its newsworthiness and mediatic lessons learned for the future of the scientific communication in a warming climate. Working at the science-media interface, we learned the role that key messages, regularity in information release, visual identity, and simplicity play in driving communication. We also confirm the central role of a two-step methodology in which scientists create content that is delivered to the public by a mediator (whether a journalist or an organization), and the importance both for scientists to actively engage with such mediators to get the message across and for journalists to look at, and trust, specific sources of information. This activity is continuing in 2023/24 as snow conditions face increasing pressure from warming temperatures and aridity. In the long run, it will bring awareness to the citizenship on the crucial role of immediate and credible climate-change adaptation strategies at multiple levels. 
Reconstructing Late Glacial Atlantic Water Advection in the Western Fram Strait: Insights from Marine Sediment Cores
Authors: Telesiński Maciej , Zajączkowski Marek
Published: March 2024

The western Fram Strait, a critical gateway connecting the Arctic and Atlantic Oceans, is presently characterized by the dominance of cold, sea-ice-laden waters from the Arctic Ocean. Nevertheless, the dynamics of the Return Atlantic Current, facilitating direct east-west recirculation across the Fram Strait, contributes significantly to the southward flow along the East Greenland shelfbreak. This study delves into the influence of Atlantic Water (AW) in the western Fram Strait over the past ~35 thousand years, employing a comprehensive analysis of marine sediment cores, including two newly acquired records.Our investigation utilizes planktic foraminiferal assemblages, stable isotopes, and X-ray fluorescence (XRF) data to unravel the historical patterns of AW advection. During late Marine Isotope Stage 3 and the Last Glacial Maximum, the findings reveal a noteworthy influx of AW, likely occurring beneath a substantial layer of surface Polar Water. The spatial extent of AW varied, reflecting the dynamic interplay with the Greenland Ice Sheet's expansion.Throughout the deglaciation phase, the western Fram Strait experienced disruptions in AW inflow due to the influence of meltwater, further shaping the regional dynamics. The interplay between AW and environmental factors, such as the evolving Greenland Ice Sheet, emerges as a key driver influencing the spatial distribution of AW during this critical climatic transition.Challenges arise in reconstructing the Holocene history of the western Fram Strait, marked by carbonate dissolution and low sedimentation rates. However, our data point towards persistent and robust AW advection to the region, extending at least since the onset of the present interglacial period. Despite limitations in the Holocene reconstruction, the cumulative evidence underscores the enduring influence of AW on the western Fram Strait, revealing a complex interplay of climatic and glacial dynamics.This research sheds light on the intricate relationship between AW dynamics and regional environmental changes, offering valuable insights into the past variability of the western Fram Strait. The findings contribute to a deeper understanding of the factors driving oceanic circulation patterns in this pivotal gateway, with implications for comprehending broader climate dynamics and projecting future changes in the Arctic-Atlantic interface.
AmazonFACE – A large-scale Free Air CO2 Enrichment Experiment in the Amazon rainforest 
Authors: Rammig Anja , Lapola David ,   AmazonFACE Team
Published: March 2024

Tropical rainforests play an important role in the global carbon cycle. They store massive amounts of biomass in their trees and soils, and contribute to climate mitigation by removing carbon from the atmosphere through photosynthesis. It is assumed that plant responses to rising atmospheric CO2 concentrations may have induced an increase in biomass and thus, increased the carbon sink in forests worldwide. Rising CO2 directly stimulates photosynthesis (the so-called CO2-fertilization effect) and tends to reduce stomatal conductance, leading to enhanced water-use efficiency, which may provide an important buffering effect for plants during adverse climate conditions and also have implications for water resources by reducing the loss of soil moisture through transpiration. For these reasons, current global climate simulations consistently predict that undisturbed tropical forests will continue to sequester more carbon in aboveground biomass. However, several lines of evidence point towards a decreasing carbon sink strength of the Amazon rainforest in the coming decades, potentially driven by nutrient limitation, droughts or other factors. Mechanistically modelling the effects of rising CO2 in the Amazon rainforest are hindered by a lack of direct observations from ecosystem scale CO2 experiments. To address these critical issues, we are currently building a free-air CO2 enrichment (FACE) experiment in an old-growth, highly diverse, tropical forest in the Brazilian Amazon and we here present our main hypotheses that underpin the AmazonFACE experiment.  We focus on possible effects of rising CO2 on carbon uptake and allocation, phosphorus cycling, water-use and plant-herbivore interactions, and discuss relevant ecophysiological processes, which need to be implemented in dynamic vegetation models to estimate future changes of the Amazon carbon sink. We give an update on the state of the experiment construction, present the sampling strategy and discuss our approach to upscale tree-level responses to stand scale. 
Widespread near-coastal bedrock erosion surfaces in East Antarctica and their implications for long-term ice-sheet behaviour
Authors: Paxman Guy , Jamieson Stewart , Ross Neil , Carter Charlotte , Bentley Mike , Jordan Tom , Cui Xiangbin , Lang Shinan , Siegert Martin
Published: March 2024

The sub-ice topography of East Antarctica provides a crucial record of the long-term geological, geomorphological, and glaciological evolution of the continent. In particular, the morphology of the East Antarctic Ice Sheet (EAIS) bed is a valuable and hitherto underexploited archive of past ice-sheet behaviour. Analysis of the subglacial landscape can therefore help improve our understanding of the response of the ice sheet to episodes of warming in the geological past that serve as analogues for current and projected future climate change.Here, we conduct a systematic search of the extensive repositories of airborne ice-penetrating radar data acquired in the past two decades to map the distribution of low-relief subglacial bed surfaces close to the East Antarctic ice margin between Princess Elizabeth Land and George V Land (70°E to 160°E). Individual surfaces are characterised by consistent elevations over distances of 10s to 100s of kilometres and relatively low-amplitude, high-frequency roughness (i.e., valleys and inselbergs). We map 31 separate low-relief bed surfaces, which range from 500 to 50,000 km2 in area and comprise ~40% of the perimeter of this sector of the East Antarctic margin. The surfaces are typically overlain by cold-based, slow-moving ice and bounded by deep subglacial troughs that host fast-flowing ice streams and outlet glaciers.Underneath the modern-day EAIS, these low-relief bed surfaces are situated at a broad range of elevations. However, when the elevations are isostatically adjusted for the removal of the EAIS, the distribution narrows substantially and, alongside cluster analysis of the morphology of the surfaces, indicates that they constitute a single, statistically consistent population around the entirety of this sector of the EAIS margin. Under ice-free conditions, the coastal surfaces would be situated above sea level and gently dipping in a seaward direction, and we suggest that they are remnants of a widespread fluvial planation surface formed following Gondwana break-up and preserved with only minor geomorphological modification since EAIS inception. The presence of these ancient surfaces has important implications for the past, present, and future behaviour of this sector of the EAIS.
Understanding the role of emissions in future air-quality scenarios over Central Europe
Authors: Prieto Perez Alvaro Patricio , Huszar Peter , Karlicky Jan
Published: March 2024

Air quality depends on emissions, but climate and meteorology also play a role in it. To understand better the contribution of each of these factors, we have to study the evolution of air pollution by varying these drivers. In this study, we are investigating the role that changes in emissions play in air-quality following the RCP4.5 and RCP8.5 scenarios for the 2026-2035 and 2046-2055 decades. We assume that the changes of climate conditions are negligible in comparison to changes in emissions, thus isolating the contribution of emission changes in future air pollution. To carry out the study, a simulation with present-day (2010-2019 decade) emissions and meteorology was performed, and another four simulations with future emissions are being carried out at the moment. The emission input for 2010-2019 was compiled using the Flexible Universal Processor for Modeling Emissions (http://www.fume-ep.org/), and the two future decades were created by applying scaling factors on the present-day emissions based on the mentioned RCPs. The simulations are being performed both by the Weather Research and Forecast with online chemistry version 4.0.3 (WRF-Chem) model and the Comprehensive Air-quality Model with Extensions (CAMx) version 7.20. The present-day simulation is being validated by studying several pollutants (such as NO2, O3, SO2, CO, PM10 and PM2.5) and meteorological variables and comparing them with observational data.
Comparing the Capability of Multi- and Hyperspectral Remote Sensing Data in Lithological Mapping Using Machine Learning Algorithms: A Case Study from Sudan
Authors: Elrasheed Abdelmajeed A. , Szabó Szilárd
Published: March 2024

Lithological mapping is vital approach in a variety of geological applications such as mineral exploration, study and understand the origin and tectonic setting for the area under investigation. However, it’s challenging to conduct this task in the traditional way mainly in remote areas characterised by rugged topography such as Red Sea. Recently, the integration of remote sensing and machine learning provide an effective quick and low-cost approach in lithological mapping. The aim of this research was to compare the potentiality of Landsat 9 multi-spectral and PRISMA hyperspectral remote sensing data in lithological mapping in Red Sea Area, N-E Sudan. We employed Random Forest (RF) and Naïve Bayes (NB) machine learning algorithms. The study area is covered mainly by; Ophiolite, Meta-volcanic, Marble, Granitoids, Altered rocks and superficial deposits. The results showed that, PRISMA hyperspectral data obtained better classification result compare to the Landsat 9 multi-spectral data using both classifiers. Also, our finding proved that, RF out performance NB in the multi- and hyperspectral datasets. E.g.  NB classifier gave Kappa 0.90 and 0.80 while RF provided 0.95 and 0.90 for PRISMA and Landsat 9 respectively. Moreover, the OA was 0.96 and 0.92 for PRISMA and 0.92 and 0.83 for Landsat 9. We firmly recommend this approach as an effective method for mapping lithology in the area where the rocks are cropped out and free vegetation cover regions.--- Abdelmajeed A. Elrasheed is funded by the Stipendium Hungaricum scholarship under the joint executive program between Hungary and Sudan.The study was elaborated under the research project NKFI K138079.
Cosmogenic signal of the stream boulder cover effect 
Authors: Lodes Emma , Scherler Dirk
Published: March 2024

Boulders are ubiquitous in bedrock river channels, moving only when the discharge and slope are large enough to transport them; as a result, large boulders in river channels may retard stream incision by blocking the erodible surface of the channel bed. This cover effect of boulders in stream channels has been demonstrated in models, but we lack field data to test it and understand how it varies with rock type and climate. We collected amalgamated stream boulder samples for in situ 10Be and 14C cosmogenic radionuclide analysis from catchments in humid-temperate, mediterranean, and semi-arid zones in the Chilean Coastal Cordillera. We present preliminary results, including new cosmogenic nuclide data from small (1-5 km2) main catchments in each climate zone and three very small (~0.05 km2) catchments in the semi-arid zone along with grain size analysis (Wolman pebble counts; >100 measurements per locality) for the catchments and adjacent hillslopes, and compare with published 10Be concentrations of stream sediment from van Dongen et al. (2019) and hillslope boulders from Lodes et al. (2023). The humid-temperate catchment has the lowest mean stream boulder 10Be concentrations (normalized to sea level high latitude production rates) at 0.52×105 a g-1, followed by the mediterranean (1.82×105 a g-1) and the semi-arid catchment (4.56×105 a g-1). We obtained a 14C concentration for one boulder sample in the humid-temperate zone so far, at 2.31×105 a g-1. In the main catchments of all three climate zones, stream sediment samples show a negative trend where larger sample grain sizes have lower 10Be concentrations, possibly due to increased erosion of the boulder surfaces or shielding due to overturning. Deposition by landslides can be ruled out in the humid and semi-arid catchments, but not in the mediterranean. In contrast, the three very small catchments in the semi-arid zone show a positive relationship between grain size and 10Be concentrations, suggesting that in these catchments, discharge and slope are too low to frequently overturn or erode the largest grains. In addition, in the semi-arid catchments boulders on hillslopes are larger and have higher 10Be concentrations than boulders in streams, whereas in the mediterranean catchment we observe the opposite pattern, suggesting that in the semi-arid catchments, the largest boulders may stay on the hillslopes until they have weathered to a size small enough to be transported to the stream channels. Next steps include analyzing 14C data for the remaining catchments and further analysis of boulder nuclide concentrations using a modelling approach.
The radiative impact of the 2022 Hunga Tonga-Hunga Ha’apai stratospheric eruption: a 2-year perspective
Authors: Sellitto Pasquale , Belhadji Redha , Duchamp Clair , Podglajen Aurélien , Carboni Elisa , Siddans Richard , Kloss Corinna , Legras Bernard
Published: March 2024

The underwater Hunga Tonga-Hunga Ha’apai (HTHH) volcano erupted in the early hours of 15th January 2022 and injected volcanic gases and aerosols to over 50 km altitude. This eruption produced the largest global perturbation of stratospheric aerosols since the Pinatubo eruption in 1991 and the largest perturbation of stratospheric water vapour observed in the satellite era. Using offline radiative transfer modelling and observations, it was shown that the combined radiative effect of the water vapour and aerosol perturbations from the HTHH eruption produced a positive radiative forcing at TOA (top-of-atmosphere), leading to a net warming of the climate system, and a fast radiatively-driven plume descent, during the first month after the event (Sellitto et al., 2022). This was the first time a warming effect on the climate system and a plume sinking was linked to volcanic eruptions, which usually produce a transient cooling and a possible plume lofting. Building on these first analyses, we synthesise satellite, ground-based, in situ and radiosonde observations accumulated after 2 years since the eruption and we investigate the evolution of the radiative impacts at this temporal scale. As aerosols sedimented and the water vapour was entrained in the ascending branch Brewer–Dobson circulation, a  clear vertical separation of the stratospheric aerosol and the moisture anomaly were observed; the effect of this vertical separation on the TOA radiative forcing and localised atmospheric diabatic heating/cooling is analysed and discussed. Reference:Sellitto, P., Podglajen, A., Belhadji, R. et al. The unexpected radiative impact of the Hunga Tonga eruption of 15th January 2022. Commun Earth Environ 3, 288 (2022). https://doi.org/10.1038/s43247-022-00618-z
Influencing factors of durum wheat productivity under current and future climatic conditions
Authors: Grosse-Heilmann Malin , Cristiano Elena , Viola Francesco , Deidda Roberto
Published: March 2024

Durum wheat is a critical staple crop in arid and semi-arid regions worldwide, that plays a significant role in local food security. Providing essential nutrients and a high protein content, it is widely used for the production of pasta and couscous. Various constraints and drivers affect durum wheat productivity, including biotic and abiotic stressors, agronomic practices, and CO2 concentrations. Their influence varies based on duration and intensity of the stressor, as well as the durum wheat growth phase in which they occur. Drought and heat were shown to act as primary yield limiting factors. Furthermore, the water footprint, a comprehensive measure for the volume of water associated with crop production, helps to analyse durum wheat cultivation from a water-food nexus perspective. Given that climate change is affecting the main influencing factors of durum wheat’s productivity and of its water footprint, such as precipitation, temperature, and atmospheric CO2 levels, its cultivation is expected to undergo alterations as well. In this context, we explore the present state of durum wheat productivity and the potential influence of changing climatic conditions on its future cultivation worldwide. The current state of research on future durum wheat production is characterised by contradictory results, compromising projections of significant declines due to heat and drought stress as well as strong increases in productivity as a consequence of the CO2-fertilisation effect, for the same or nearby locations. Understanding the complex interactions between climate change, durum wheat productivity and the associated water footprint is of great importance to derive sustainable adaptation strategies and move one step closer into ensuring future food and water security.
Characterising the Vertical Canopy Structure of Vegetation and its Impact on Radiation Regimes using Spaceborne LiDAR
Authors: Satapathy Trupti , Dutta Debsunder
Published: March 2024

Forests are the most complex ecosystem on the planet and and play a crucial role in the exchange of mass and energy between the land surface and atmosphere. India's tropical region encompasses a diverse range of ecosystems, including deserts, mangroves, shrublands, deciduous, and evergreen forests, contributing to its ecological diversity. The varied canopy structural attributes of these vegetation types impact the exchange of carbon and water fluxes between the land surface and the atmosphere. We use high-resolution spaceborne data from the Global Ecosystem Dynamics Investigation (GEDI) to map the variability of vegetation canopy attributes at a synoptic scale. The total canopy height (RH100), foliage density (PAI) and foliage height diversity (FHD) demonstrated wide variability across the country and clearly differentiated the forested regions from the other land covers. The distribution of the canopy structural attributes in the forested regions and biomes also exhibited significant change across the years 2019-2021 with p-value < 0.05 (from the Kolmogorov–Smirnov test). Further, we fitted α and β (shape and scale) parameters of the Beta distribution function to the PAVD data from GEDI to compactly represent the spatial variation of the vertical variability of canopy. The high coefficient of determination (R2 = 0.80) between the fitted beta distribution function and GEDI-PAVD suggests an effective representation of canopy vertical variability. Based upon the fitted parameters α and β, k-means clustering was performed which resulted in six distinct canopy structure classes. Differing canopy structures led to significant variations in radiation regimes throughout the day. Our observations suggest that incorporating Beta distribution-fitted shape and scale parameters into multi-layer canopy models enhances the estimation of flux exchanges over terrestrial ecosystems by capturing vertical variations in canopy structure.Keywords: GEDI, Canopy structure, Plant area volume density, Beta distribution function