bluuebunny/crossref_metadata_2025 huggingface dataset:
The potential of subsurface heat recycling in Dresden
Authors: Dohmwirth Verena , Benz Susanne , Mauder Matthias
Published: March 2024

In times of climate change heat increasingly accumulates in urban areas. Thus, the temperature in city centers is often several degrees higher than in the surrounding areas. This urban heat island effect (UHI) can negatively affect people and the environment. Heat islands in the subsurface (SubSUHI) due to high heat input from cities into the soil and groundwater can also be measured. This accumulated heat input could be harnessed by geothermal heat pumps contributing to the solution of two major challenges of our time: firstly, the reduction of CO2 emissions through the decarbonization of the heating market and secondly, the cooling of the soil and groundwater to pre-industrial temperature levels and thus a possible climate protection measure.This work attempts to investigate the heat island effect in the subsurface of the urban area of Dresden, Germany. For this purpose, various temperature measurements, such as groundwater and air temperature, are combined with geodata on land use and development. The theoretical geothermal potential for suitable areas in Dresden is calculated as well as the sustainable geothermal potential, taking into account the heat flux directed upwards as well as downwards. Several, mostly anthropogenic, heat fluxes from urban structures into the groundwater are investigated, such as heat fluxes due to buildings, tunnels, or district heating. These potentials are placed in the context of the heating requirements of the city of Dresden and thereby descripe the extent to which the installation of geothermal systems can contribute to the climate neutrality of the local heating market. In a second scenario, the heat fluxes for the year 2100 are calculated using the CMIP6 scenarios SSP245 and the SSP585 to show how climate change could potentially improve the efficiency of geothermal systems. By using Google Earth Engine as a platform, we ensure that our analysis is easily scalable and can later be applied to any city within Germany.
Diffusion and sorption of caesium depend on the dry bulk density of bentonite
Authors: Hennig Theresa , Grossmann Sina , Brendler Vinzenz
Published: March 2024

Smectite-rich natural clays, usually referred to as bentonite, are used as backfill material in disposal concepts for highly-radioactive wastes. The main component of bentonite is montmorillonite, characterised by a high cation exchange capacity resulting from isomorphous substitution and swelling due to the incorporation of water molecules between the stacked clay platelets, the interlayer. These properties render bentonite an ideally suited barrier material for cationic radionuclides. Caesium is such a radionuclide that is relevant in the context of nuclear waste disposal since it is highly soluble and can be incorporated in organisms.Migration of caesium in MX-80 bentonite (Na-montmorillonite) was investigated for different dry bulk densities (1.3, 1.6 and 1.9 g/cm³) in long-term through-diffusion experiments running for up to 600 days. Diffusion experiments of tritiated water (HTO, non-sorbing) provided the transport accessible porosities. Batch sorption experiments at varying caesium concentrations should test the transferability between dispersed and compacted systems by means of the distribution coefficient Kd (m³/kg). The synthetic pore water compositions were calculated as a function of the dry bulk density. Caesium and HTO are expected to migrate via molecular diffusion through the compacted bentonite sample. Therefore, a one-dimensional numerical model was applied to determine the transport parameters, effective diffusion coefficient De (m²/s) and rock capacity factor α (-), from the temporal evolution of the diffusive flux and the accumulated activity.In the dispersed systems, measured Kd values increase with decreasing caesium concentration and dry bulk density. The linear sorption isotherm indicates that sorption mainly occurred via cation exchange, predominantly with ions from the interlayer. Accordingly, the higher the cation concentration in the contacting pore water, less caesium is exchanged due to competing effects. At low concentrations (
Coupled multiphysics approach to characterize groundwater flow system around a near-surface fault zone
Authors: Gresse Marceau , Miyakoshi Akinobu , Komori Shogo , Hosono Hinako , Tosaki Yuki , Sato Tsutomu , Asahina Daisuke , Tsukamoto Hitoshi , Otsubo Makoto , Takeda Mikio
Published: March 2024

Fault zones intensively disturb local hydrogeologic structures, and, consequently, can play a critical role in governing small to large-scale groundwater flow. Extensive studies have focused on the permeability variation along faults in the light of the conduit or barrier function for the deep groundwater flow. However, little attempt has been made to characterize the hydrological functions of near-surface fault zone.Exposed to atmospheric conditions, fault zones are further disturbed by stress relief and chemical weathering, modifying their structure and generally increasing their permeability. Consequently, the fault zone, which functions as a recharge or discharge zone at the near surface, exerts a non-negligible influence on groundwater flow. However, identifying the hydrological function of near-surface fault zone remains challenging when relying solely on conventional, often non-integrated, geophysical or hydrological investigation approaches.This study proposes a multiphysics coupled strategy to understand the groundwater flow regime around near-surface fault zone. The proposed approach is applied to an active reverse fault zone in Kamikita Plain, NE Japan, which extends for 30 km within the recharge zone of the catchment.The proposed multiphysics approach consists of 5 successive steps:2-D Electrical Resistivity Tomography (ERT) Survey: A 2.3 km-long profile crossing the fault zone, consisting of 7 roll-along surveys with a 6-m electrode spacing.
Self-Potential Survey: Conducted along the 2.3 km ERT profile.
Rock Property Characterization: A 80 m deep borehole was drilled in the fault zone and physical properties were measured.
3-D Groundwater Flow Simulation of the Fault Zone: Utilizing areal hydrogeological data, measured rock properties, and geophysical imaging.
Model Validation Process: Using the results from the groundwater flow simulation, electrical conductivity and self-potential responses were calculated, and compared with observed field data.
Preliminary results successfully reproduce the overall resistivity signature and the self-potential anomaly (+35 mV) in the fault zone, attributed to local groundwater upwelling. This newly proposed multiphysics approach could be an essential tool to evaluate the groundwater flow in a region including large-size fault zone, which is important for radioactive waste disposal. Furthermore, this approach could also be effective in capturing the local fluid flow circulation for a variety of applications.Acknowledgements: Main part of this research project has been conducted as the regulatory supporting research funded by the Secretariat of the Nuclear Regulation Authority, Japan.
Assessing the value of seasonal flow forecasts in reservoir operations for drought management in South Korea
Authors: Lee Yongshin , Peñuela Andres , Pianosi Francesca , Rico-Ramirez Miguel
Published: March 2024

Given the escalating uncertainty in water resources management attributed to climate change, the significance of reliable flow forecasts becomes increasingly crucial. Recent technological advancements have brought attention to seasonal weather forecasts, which provide predictions of weather variables for the next several months. Accordingly, numerous studies have investigated the skill of Seasonal Flow Forecasts (SFFs) forced by seasonal weather forecasts, in various regions and countries. Our previous work on the skill of SFFs across South Korea demonstrated that SFFs generally outperform Ensemble Streamflow Prediction (ESP) up to 3 months ahead and exhibit notably higher skill during the wet season in abnormally dry years.This study builds upon our earlier research with the objective of evaluating the value of SFFs for reservoir operations for drought management. This analysis is conducted for two pivotal reservoirs, Soyanggang and Chungju, which serve as the major water sources for the metropolitan area, including the capital city, Seoul. For the severe drought period from July 2014 to June 2016, we used model simulation to compare different reservoir operation models: the Simple Conjunctive Operation (SCO) model, forced by either a worst-case or low inflow scenario (similarly to what currently done in reality) and the Forecast-informed Conjunctive Operation (FCO) model, forced by either ESP or SFFs. Multi-objective evolutionary algorithm is utilised to optimise release scheduling with two objective functions: securing storage volume at the end of the hydrological year and minimizing supply deficit over the entire year. We explore the impact of using different reservoir operation models, different forecasting lead times, as well as different ways to determine a ‘best compromise’ solution between the two competing objectives.
Unravelling the complexity of multi-risk systems and adaptation pathways
Authors: Schlumberger Julius , Haasnoot Marjolijn , Aerts Jeroen , Bril Veerle , van der Weide Lars , de Ruiter Marleen
Published: March 2024

Disaster Risk Management (DRM) is increasingly complex due to interacting climate risks from concurrent hazards. The Dynamic Adaptive Policy Pathways for Multi-Risk (DAPP-MR) framework has been introduced to assess DRM policies' effectiveness under deep uncertainties - such as future climate change - and to develop integrated adaptive strategies considering interactions across hazards, sectors, and time. So far, no use cases were available that provide evidence regarding the utility of DAPP-MR.In this presentation we examine DAPP-MR through a synthetic multi-risk modelling case study, focusing on DRM pathways for managing flood and drought risks across different sectors for a period of 100 years. The case study, inspired by a Dutch river delta, accounts for multi-hazard interaction effects such as including co-occurring or preceding droughts amplifying flood risk, and consecutive flood events as well as multi-sector dynamics. While providing insights into the model development process, the result analysis and conclusions, we also discuss the challenges and benefits of combining multi-risk thinking and climate change adaptation decision-making approaches and the implications of multi-risk dynamics on trade-offs and synergies of different risk management strategies.
A new extended record of Lower to lower Upper Aptian deposits in Northern Germany – new insights in the Boreal Oceanic Anoxic Event 1a
Authors: Bornemann André , Blumenberg Martin , Erbacher Jochen , Koch Rüdiger , Lippmann Robert
Published: March 2024

A recently cored 49-m-thick succession of Early to early Late Aptian age from Garbsen, a small city 6 km northwest of Hannover, has been studied with respect to sedimentology, bulk organic geochemistry and biostratigraphy.The basal 14 m cover an alternating paper shale-mudstone sequence (topmost Hoheneggelsen Formation) with a 2.3-m-thick “Fischschiefer” bed at the top. It is overlain by partly reddish-colored hemipelagic marlstones representing lithostratigraphically the Sarstedt Member, formerly also named Hedbergella Marls. The “Fischschiefer” is considered to represent the local expression of the global Oceanic Anoxic Event 1a in the Lower Saxony Basin. During Early Cretaceous times the Hannover area represented paleogeographically the eastern-central part and, thus, the depocenter of the Lower Saxony Basin.In addition to detailed lithological data, we present high-resolution δ13Corg, CaCO3 and TOC data as well as a calcareous nannofossil biostratigraphy for this Boreal Aptian succession. This new core complements other records in the western part of the basin (Alstätte, Bottini et al., 2012) as well as southeast of Hannover (Hoheneggelsen KB9, Heldt et al., 2012) and, due to its completeness, provides new insights in the transition from the “Fischschiefer” deposit to the hemipelagic marlstone sedimentation. References:Bottini, C., Mutterlose, J., 2012. Integrated stratigraphy of Early Aptian black shales in the Boreal Realm: calcareous nannofossil and stable isotope evidence for global and regional processes. Newsl Stratigr 45, 115–137. doi:10.1127/0078-0421/2012/0017Heldt, M., Mutterlose, J., Berner, U., Erbacher, J., 2012. First high-resolution δ13C-records across black shales of the Early Aptian Oceanic Anoxic Event 1a within the mid-latitudes of northwest Europe (Germany, Lower Saxony Basin). Newsl Stratigr 45, 151–169. doi:10.1127/0078-0421/2012/0019
Tianwen-1 MINPA in-flight operation and first science results
Authors: Li Wenya , Kong Linggao , Ma Jijie
Published: March 2024

The Mars Ion and Neutral Particle Analyzer (MINPA), one of the seven scientific payloads onboard the Tianwen-1 orbiter, was specifically designed to investigate the interaction between the solar wind and Mars by analyzing ions and energetic neutral atoms (ENAs). Commencing its scientific data collection in November 2021, MINPA successfully completed its first far-magnetotail survey during the summer of 2022. Our presentation will provide a comprehensive overview of MINPA's in-flight operations and its initial scientific findings. Regarding ENA observations, MINPA achieved successful data collection during solar wind, magnetosheath, and nightside observations. An algorithm has been developed to convert ENA count rates into intensity. A statistical analysis of solar wind ENAs revealed a neutralization rate of the solar wind at the flanks of the Mars magnetosphere. We also performed a collaborative analysis using MINPA data and numerical modeling to gain a deeper understanding of the ENA spectrum and its properties. In the ion component, MINPA observed hydrogen and heavy ions across various regions at Mars. With a far apoapsis, MINPA measured heavy ion escape in the far magnetotail, showcasing significant enhancements during periods of coronal mass ejection (CME) impacts. To enhance our understanding of the Martian space environment, an interdisciplinary team, comprising scientists from the Tianwen-1, Emirates Mars Mission (EMM), Mars Atmosphere and Volatile Evolution (MAVEN), and Mars Express missions, has been assembled within the ISSI framework.
Natural variability has dominated the movement of High Asia Polar Jet over the past six centuries
Authors: An Wenling , Treydte Kerstin , Xu Chenxi , Yin Qiuzhen , Babst Flurin , Liu Laibao , Zhang Qiong , Neukom Raphael , Wang Zhenqian , Guo Zhengtang
Published: March 2024

Recent northward movement of polar jet has been linked with mid-latitude weather and climate anomalies, but distinguishing the natural variability and anthropogenic activity is hindered by a lack of long-term observations. Here we use tree ring oxygen records from the High Asia to reconstruct variability in the movement of the late spring High Asia Polar Jet (HAPJ) over the past six centuries. We find that the HAPJ has shown a gradually northward trend since 1600s, which have resulted in relatively wet conditions in the High Asia and southern west Asia from 1600s to late 1800s and recent decades. Combined with model results, we ﬁnd the HAPJ is dominated by the phase changes of North Atlantic Oscillation and volcanic eruption at decadal to multi-decadal scales. At multi-decadal to centurial scales, solar activity is the largest contributor to HAPJ movement, while the contribution of increasing greenhouse gas is relatively small. These results highlight the importance of natural variability in HAPJ movements under the context of global warming.
The influence of sediment isostatic adjustment on sea-level change and its records along the coast of Taiwan
Authors: Ho Andrew , Shyu J. Bruce H. , Tan Eh , Ferrier Ken L.
Published: March 2024

Information of sea-level change history is crucial for the understanding of tectonic movements along coastal areas.  Locally, changes in sea-level may be influenced by sediment isostatic adjustment (SIA) that results from erosion and deposition and perturbs crustal elevation and the Earth’s gravitational field.  However, many previous studies on coastal uplifts neglected such effects.  In this study, we utilized gravitationally self-consistent sea-level model to quantitatively analyze how SIA affected the sea-level during the last glacial-interglacial cycle around Taiwan, where erosion and deposition are among the fastest in the world.  We constructed a time-variant sediment transfer history for Taiwan and used it, together with published ice loading history over the past 122 kyr, as input to drive the sea-level model.  To build a comprehensive sediment model, we combined erosion and exhumation rate data derived from cosmogenic nuclides, detrital zircon fission-track, and fully reset apatite fission track ages to construct the erosion rate map.  In addition, we compiled age data from both on-land and offshore sediment cores, and isopach map derived from submarine seismic profiles to generate the deposition rate map.  The modeling results show that SIA would cause significant spatial variations in sea-level history along the coast of Taiwan.  For example, along the eastern coast, isostatic uplift due to the high rate of erosion of nearby mountains induces sea-level fall, whereas isostatic subsidence resulting from deposition may surpass the effect of erosion and lead to sea-level rise along the southwestern coast.  This may be the first observation of completely different isostatic patterns of coastlines occurring in such a short distance, likely owing to the extremely rapid sediment redistribution and the relatively thin elastic lithosphere of Taiwan.  Furthermore, the effects of SIA may produce sea-level variations in the order of meters to tens of meters since 10 ka, and up to tens to more than two hundred meters since 122 ka along Taiwan’s coast.  Without the consideration of SIA effects, the estimation of tectonic coastal uplift rates may be overestimated or underestimated by up to 60% and 90%, respectively, along some coast of Taiwan.  Our results highlight the importance of considering SIA processes when using paleo-sea-level indicators to characterize tectonic movements along the coast, especially in regions with rapid erosion or deposition.
Patterns of Treeline Rise with Climate Change Across Western North America from the 1980s to Present
Authors: Corimanya Joanna , Jimenez-Garcia Daniel , Peterson A. Townsend
Published: March 2024

Previous research has shown that (1) treelines are shifting upward in elevation on high mountain peaks worldwide, and (2) the rate of the upward shift appears to have increased markedly in recent decades. Because treeline shift is a process manifested over broad scales of space and time, a particular challenge has been that of obtaining a broad-enough view of patterns of treeline shift to permit inferences about geographic and environmental patterns. What is more, intensive studies of treelines have been concentrated in North Temperate regions, such that little information is available about treeline shift patterns in the Tropics. We have attempted to broaden this viewpoint by means of analysis of long  time series of vegetation indices derived from Landsat imagery obtained and analyzed via Google Earth Engine for the 1980s to present. We sampled vegetation indices at points spaced every 100 m along 100 km transects radiating out from 120 high peaks across western North America (Canada to Central America); considerable data preparation was necessary, including ending transects
Nitrogen deposition effect on tree growth depends on climate, tree size, and leaf habit
Authors: Vallicrosa Pou Helena , Grossiord Charlotte
Published: March 2024

The increase of nitrogen (N) deposition is a human-induced process associated with industry and agriculture that disrupts the nitrogen biogeochemical cycle. N deposition has been associated with environmental impacts such as land carbon sink increase, loss of biodiversity, and risk of eutrophication and acidity but further understanding of how N deposition affects trees of different environmental conditions, size, and leaf habit is missing. In this study, we use the ICP forest inventory data and the EMEP N deposition data to track how N deposition affects tree growth in interaction with temperature and precipitation, tree size classes, or leaf habits in Europe since 1990. We use linear mixed models to describe the interaction between mean annual temperature (MAT) mean annual precipitation (MAP) and N deposition in tree growth. In addition, we use gam models to track the different saturation points. We found contrasting interactions between N deposition and temperature in conifers and broadleaves. Conifers living in colder environments have a more positive response to N deposition than conifers living in warmer environments. On the other hand, broadleaves living in warmer environments had the most positive response to high N deposition levels. Interestingly, broadleaves showed lower saturation points than conifers, being around 25 kg ha yr and 30 kg ha yr respectively. Nonetheless, factors such as tree size and species can modulate such relations, being especially relevant for secondary forests or restoration processes. In conclusion, our findings point out climate, tree size, and leaf habit as strong modulators of N deposition impacts in tree growth that should be considered in future assessments and policy-making, especially in Europe. Further research is needed to certify these relations in other regions of the world.
High-resolution 3D geomodel of the central Po-Plain, Northern Italy.
Authors: Barrera Daniel , Toscani Giovanni , Amadori Chiara , Fantoni Roberto , Di Giulio Andrea
Published: March 2024

The Po Plain in Northern Italy constitutes an elongated alluvial valley characterized by an intricate geological evolution, extending from the late Paleozoic era to recent times. Notably densely populated, this region accommodates approximately one-third of the Italian population and hosts critical industrial facilities, coupled with a substantial history of oil and gas exploration and production. Given these factors, the creation of a high-resolution subsurface geomodel is imperative for various applications in this region.Tectonically, the Po Plain is located in the Adria Microplate and is bounded by two opposite verging orogens sharing the same foreland: the Northern Apennines (NA) to the south, and the Southern Alps (SA) and the Western Alps to the north and the west. The SA are a south-verging fold-and-thrust belt, while the NA are a north-northeast-verging fold-and-thrust belt; both belts have their outer thrust front buried beneath the Neogene-Quaternary sediments of the Po Plain. The front of the Northern Apennines is structured into three different arcs with increasing amounts of shortening, from northwest to southeast: the Monferrato Arc, the Emilia Arc, and the Ferrara Arc. Along the Emilia Arc, the juxtaposition of the buried Southern Alps and the buried Northern Apennines is notably close, allowing for a more detailed analysis of their frontal convergence (a few kilometers). Moreover, the influence on the thrust(s) geometry from the inherited and inverted structural highs from the passive Mesozoic platform can be observed more clearly. This combination of factors, among others, makes the central area of the Po-Plain one of the most prolific for oil and gas production, hosting several productive fields.Despite the long story of hydrocarbon exploration and production, a large-scale comprehensive 3D model using seismic lines and well information has not yet been published, apart from a couple of very good seismic sections, that have been studied and analyzed multiple times. In particular, the Plio-Pleistocene architecture of the basin has been only partially described. In this study, we have used an extensive database provided by ENI Spa to create a high-definition static model and several balanced cross-sections to understand better the distribution of the deformation along the Emilia arc and to comprehend how the complex relationship between NA, SA, and the inherited structural highs have driven the actual architecture of the central Po-Plain subsurface. This new highly detailed 3D geomodel provides the necessary base to implement renewable energy developments (geothermic) in one of the most populated areas in Italy.
The Influence of Climate Teleconnections on Global Burned Area
Authors: Qu Yuquan , Vereecken Harry , Veraverbeke Sander , Montzka Carsten
Published: March 2024

Wildfires are known to be controlled by fuels and weather. Climate teleconnections may influence wildfires by altering fuel availability and fire weather. In this study, we used the random forest approach to systematically detect relationships between teleconnection climate indices (CIs) and burned area while accounting for different lag times. Results indicate that burned area is especially modulated by climate teleconnections in Africa and Australia. The Tropical Northern Atlantic (TNA) pattern was the most influential CI for the global burned area, followed by the El Niño Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), and the Pacific–North American (PNA) pattern. To study pathways of how teleconnections affect the burned area, we distinguished two classes of fire drivers: bottom-up fuel availability and top-down weather conditions. Bottom-up fuel drivers showed higher correlation with CIs than top-down weather drivers and served as mediators between teleconnections and wildfires. The mediating effect of top-down weather drivers was only apparent in specific seasons. Our study highlights that in teleconnection-wildfire hotspot regions, knowledge of the relation between CIs and drivers of wildfires could improve long-term wildfire predictability. We recommend that bottom-up fuel drivers should also be integrated into wildfire predictive frameworks as they play an important mediating role in linking teleconnections and wildfires.
Root Dynamics Under Elevated CO2 in a Free Air Carbon Enrichment (FACE) Experiment
Authors: Handy Grace , Mackenzie Rob , Esquivel-Mulebert Adriane , Arnaud Marie , Kourmouli Angeliki , Carter Imogen , Wilikinson Matthew , Mayoral Carolina
Published: March 2024

Evidence supporting a carbon fertilisation effect, where increasing levels of carbon dioxide (CO2) in the atmosphere lead to photosynthetic enhancement in trees, suggests that forests can sequester more carbon under elevated CO2 (eCO2). However, it remains largely unclear where and for how long this carbon is stored within the forest ecosystem. To sustain photosynthetic enhancement under eCO2 concentrations, trees are likely to require higher intake of nutrients from the soil, which should stimulate root growth. This ongoing study (2022-2026) investigates the hypothesis that fine root biomass and turnover rates will increase, and proliferation will be higher at greater depths, because of eCO2. It is vital that the consequences of increased atmospheric CO2 on plant carbon allocation are understood to improve the accuracy of models projecting the future of forests as global carbon sinks.This study is carried out at the Birmingham Institute of Forest Research Free Air Carbon Enrichment (BIFoR FACE) experiment, the only FACE experiment in a mature, temperate forest simulating atmospheric CO2 concentrations to those predicted to be the mid-century planetary norm. For ambient and elevated CO2 treatments, dry biomass of fine roots, specific root length (SRL) and depth distribution were assessed. 1m soil cores, deeper than the standard 30cm, were used to investigate changes in fine root depth distribution. Changes in fine root growth rates are calculated from minirhizotron images taken at monthly intervals over a 2-year period, with 15 replicates per treatment.Average fine root biomass was >30% higher under eCO2 in all depths down to 70cm. As expected, fine root biomass declined approximately exponentially with depth under both elevated and ambient CO2 conditions, but this slope of decline was lower under eCO2. Other than in the O horizon, average SRL was also higher under eCO2 with depth, meaning roots were on average longer per unit biomass. This implies that trees adapt root proliferation and morphology to increase the volume of soil exploited under eCO2, particularly at greater depths.
A model-data comparison of North Atlantic climate variability and its responses to natural forcing over the last millennium 
Authors: Tao Qin , Sjolte Jesper , Muscheler Raimund
Published: March 2024

North Atlantic climate variability is to a large extent governed by the recurring modes of atmospheric circulation, also exhibiting impacts of volcanic and solar activities. These factors emphasize the importance of evaluating the leading variability modes and their responses to natural forcing in climate models for assessing the North Atlantic-European climate predictions. The recent availability of spatial field reconstructions of atmospheric circulation over the last millennium offers a unique opportunity for the paleo-evaluation of CMIP-PMIP models for these purposes across annual to centennial timescales. Particularly, with the possibility of comparing the spatial structure of variability.In this study, we perform a model-data comparison of the North Atlantic climate focusing on the leading variability modes (North Atlantic Oscillation, NAO; East Atlantic Pattern, EA; Scandinavian Pattern, SCA) and the imprints of major natural forcing over the last millennium. We first develop an updated version of climate field reconstructions covering the past 700 years by assimilating proxy records into isotope-enabled simulations. This new version shows improved skills in reproducing the leading variability modes to serve as a reference for the comparisons with the past1000 runs. We then evaluate the multidecadal spatial variability in winter modes from the last millennium to the end of the 21st century. The models generally have a good representation of the average spatial structures of the NAO, EA and SCA patterns, but with persistent biases in their spatial variability. Particularly, the underestimated spatial shift in the NAO centres of action is directly related to the biases in regional temperature and precipitation changes. Furthermore, we examine the volcanic and solar imprints over the last millennium. Although not all the models can reproduce the significant NAO responses to volcanic eruptions as shown in the reconstructions, they do capture some NAO-like signals mixed with the EA and SCA patterns. Overall, our model-data comparison presents some potential uncertainties in climate projections over the North Atlantic sector, which remain challenging for the reliability of future projections. Also, this model-data comparison framework presents a pathway for future studies aiming to select the better-performing models for regional climate studies.
Interactions between ocean circulation and the Northern Hemisphere ice sheets at 40 ky B.P. in an Earth System Model (iLOVECLIM-GRISLI)
Authors: Abot Louise , Waelbroeck Claire , Quiquet Aurélien , Delavergne Casimir , Bouttes Nathaelle
Published: March 2024

During the last glacial period, the climate went through rapid fluctuations together with changes in ocean circulation and ice sheets volume accompanied by iceberg discharges. These rapid climate variations, namely Dansgaard-Oeschger events, are still not fully explained. This study’s aim is to contribute to their better understanding, focusing on interactions between ice sheets and ocean circulation. To this end, we use the iLOVECLIM-GRISLI coupled climate-ice sheet model and run two different perturbation experiments related to the ice sheet and ocean components. Starting from a quasi equilibrium corresponding to 40 ky B.P. greenhouse gas concentration, incoming solar radiation and ice sheet volume, the first experiment consists in imposing either constant or amplified sub-shelf melt rates in comparison with the control simulation. In the second experiment, we focus on the interface between the ice sheets and the bedrock. The basal friction coefficient values are imposed following the same procedure. These two experiments are similar to freshwater hosing experiments but here the water comes directly from the interactively computed ice sheets change. For each experiment, the perturbation is imposed for 500 years before returning to the unperturbed conditions for one thousand years and its impacts on the climate system are investigated. Our results highlight feedbacks that may help to explain the abrupt nature of the climate transitions observed during the last glacial period. 
An Experimental Study of CO2 Flooding the Reservoir-caprock System: Implication for the Stability of Caprock during CO2 Intrusion
Authors: Zhou Bing , Lun Zengmin , Wang Bue
Published: March 2024

The study of caprock assumes paramount significance, particularly in elucidating alterations in the sealing conditions of petroleum reservoirs. However, it is imperative that corresponding simulation experiments transcend a singular focus on CO2 and caprock, extending to a comprehensive study of the reservoir-caprock system. Experimental protocols were implemented, entailing the sequential flow of CO2-rich fluid first through the reservoir and subsequently through the caprock. The chosen samples and conditions were drawn from potential CO2 utilization and storage blocks in the Subei Basin, China, featuring sandstone reservoirs and mudstone caprocks. The experimental paradigm simulated the interaction when CO2 migrating along the sandstone and then reaching the mudstone caprock, spanning a duration of 37 days.Results underscore that the introduction of CO2-rich fluid predominantly instigates the dissolution of sandstone reservoirs, with notable dissolutions observed in feldspar and clay minerals, while secondary mineral precipitation remains negligible. Upon the fluids traversal through the mudstone caprock, initial dissolution occurs in carbonate minerals, accompanied by continuous precipitation of secondary clay minerals. These secondary minerals not only occupy calcite dissolution pores but also precipitate on the surfaces of rock particles, asserting dominance in the water-rock reaction within the mudstone.Supported by geological observations and numerical simulations, these experiments illuminate the material adjustment processes ensuing from the introduction of CO2-rich fluid into the reservoir-caprock system. The infusion of CO2-rich fluid induces mineral dissolution, augmenting pore space within the reservoir, with ion products subsequently transported to the mudstone caprock. Under conditions characterized by a slower flow rate and a more extensive water-rock reaction surface area in the mudstone caprock, the water-rock interaction accelerates the dissolution and reprecipitation of calcite and other minerals. The reprecipitated minerals effectively occupy caprock pores and fractures, thereby enhancing the caprock's sealing capacity.
The link between temperature mean and variance trends in summer in France and Spain and its evolution
Authors: Parey Sylvie , Lemaire Cléo , Hoang Thi Thu Huong
Published: March 2024

In a previous work (Parey et al. 2010, [1]) a link had been identified between the trends in temperature mean and variance in Europe, with geographical and seasonal differences, and the climate models at the time performed poorly in representing the observed link. In this study, we update the results for summer temperature and go further in looking for possible causes of the observed differences between France and Spain. Then, the performance of the last CMIP6 models in representing the link is assessed in order to anticipate how this link could evolve in the future.More precisely, in summer in France the trends in mean and variance are generally positively correlated: variance increases when mean increases, whereas in Spain the reverse behavior is generally found. This behavior has been confirmed with recent observation data: individual timeseries as well as the gridded EOBS database. We show that this can be explained by the fact that summers in Spain are more constantly hot, and the variance is explained by the occurrence of milder spells, while in France, summers are mild and the variance is explained by the occurrence of hot spells. The evolution of the link throughout the 1950-2022 period has been studied and revealed that parts of the south of France recently turned toward a similar behavior as Spain, with a decrease in variance when mean increases. The investigated question then is the following: will French summers resemble Spanish summers in the future? To answer the question, the ability of CMIP6 models to represent the observed link is first assessed, and then, the evolution projected by the best performing ones toward the end of the century is studied.Better understanding the evolution of this link is important to anticipate future hot temperature extremes in France in the long term for adaptation. Owing to the larger impact of variance compared to mean on the intensity of the extremes, this question is crucial for the anticipation of future hot extremes. Do we need to anticipate a general hot summer climate in the second half of the century, or will the summers become warmer with more frequent heat waves and possible large deviations to very hot temperatures? Reference:[1] Parey S., Dacunha-Castelle D., Hoang T.T.H. : Mean and variance evolutions of the hot and cold temperatures in Europe; Clim Dyn (2010) 34:345–359, DOI 10.1007/s00382-009-0557-
Assessing hotspots of sediment sources and related sediment dynamics through the integration of geomorphological data, sediment connectivity and sediment transport modelling – The HOTSED model
Authors: La Licata Manuel , Bosino Alberto , Sadeghi Seyed Hamidreza , Maerker Michael
Published: March 2024

Sediment connectivity is a pivotal concept in geomorphological studies aimed at assessing watershed sediment dynamics. It is expressed through the spatial arrangement and physical linkages of system components (Structural Connectivity, SC) and the actual transfer of water and sediments facilitated by dynamic processes (Functional Connectivity, FC). However, a limited number of studies have simultaneously assessed SC and FC. Moreover, traditionally sediment connectivity studies primarily rely on comparing independent results from GIS modelling, field-based assessments, and mapping. Thus, it remains a common practice to treat geomorphic processes and connectivity as separate variables, often without joining them into an integrated modelling approach.Accordingly, this research aims to introduce a novel methodology that integrates geomorphological data derived from a detailed mapping approach with SC and FC. In particular, we developed a new GIS-based integrated model named HOTSED, designed to assess potential hotspots of sediment sources and related sediment dynamics at the watershed scale.We tested our approach in a geomorphologically highly active Mediterranean watershed in the Northern Apennines (Italy), starting with the elaboration of an Inventory Map (IM) of sediment sources through fieldwork, photointerpretation, terrain analysis, and digital mapping. Furthermore, we used IM-derived data to estimate the geomorphic Potential of Sediment Sources (PSS) adopting a relative scoring system. Moreover, we computed Structural Sediment Connectivity (STC) and the Potential for Sediment Transport (PST) by combining terrain and hydrological parameters, land use data, and rainfall erosivity. Subsequently, the integration of PSS, STC, and PST was achieved through a raster-based calculation method, yielding the HOTSED model.The application of the model in the study area provided a single and intuitive output depicting the location of hotspots of sediment sources. It allowed the derivation of “relative hazard” classes for sediment production and delivery using the fluvial system as target feature. The results show that HOTSED successfully highlighted hotspots associated with active complex and polygenetic geomorphic systems located in areas close to the main channels, as well as linear hotspots corresponding to tributary drainages acting as stream corridor sources. Furthermore, it successfully identified areas prone to store sediments in depositional landforms with low hazard, considering both low geomorphic potential and sediment connectivity. Thus, this study proves that our conceptual model is particularly effective in geomorphologically complex areas such as the Northern Apennines.
Global flood projection and socioeconomic implications under a physics-constrained deep learning framework
Authors: Kang Shengyu , Yin Jiabo , Slater Louise , Liu Pan , Liu Dedi
Published: March 2024

As the planet warms, the frequency and severity of weather-related hazards such as floods are intensifying, posing substantial threats to communities around the globe. Rising flood peaks and volumes can claim lives, damage infrastructure, and compromise access to essential services. However, the physical mechanisms behind global flood evolution are still uncertain, and their implications for socioeconomic systems remain unclear. In this study, we leverage a supervised machine learning technique to identify the dominant factors influencing daily streamflow. We then propose a physics-constrained cascade model chain which assimilates water and heat transport processes to project bivariate risk (i.e. flood peak and volume together), along with its socioeconomic consequences. To achieve this, we drive a hybrid deep learning-hydrological model with bias-corrected outputs from twenty global climate models (GCMs) under four shared socioeconomic pathways (SSPs). Our results project considerable increases in flood risk under the medium to high-end emission scenario (SSP3-7.0) over most catchments of the globe. The median future joint return period decreases from 50 years to around 27.6 years, with 186 trillion dollars and 4 billion people exposed. Downwelling shortwave radiation is identified as the dominant factor driving changes in daily streamflow, accelerating both terrestrial evapotranspiration and snowmelt. As future scenarios project enhanced radiation levels along with an increase in precipitation extremes, a heightened risk of widespread flooding is foreseen. This study aims to provide valuable insights for policymakers developing strategies to mitigate the risks associated with river flooding under climate change.
Mechanisms and durations of metamorphic garnet crystallization in the lower nappes of the Kalak Nappe Complex (Arctic Norway)
Authors: Yogi M. Thereza A. G. , Gaidies Fred , Heldwein Olivier K. A. , Rice A. Hugh N.
Published: March 2024

The 3D microstructure and compositional zoning of garnet populations in micaschists from the Kolvik and Bekkarfjord nappes indicate the quasi-equilibration of their major components across the rock matrices during interface-controlled, size-independent garnet growth. There is microstructural evidence for foliation-parallel, small-scale resorption of garnet rims in the Kolvik Nappe, influencing the metamorphic peak conditions obtained from thermodynamic modelling. The local chemical compositions of rims less affected by resorption indicate a peak temperature of c. 630˚C, which is c. 40˚C higher than the temperature obtained from resorbed rims of the largest garnet crystal. The use of a diffusion geospeedometry approach that considers the geometry of the compositional zoning of the entire garnet population, and the higher, more realistic peak temperature, results in an estimated duration of 1 to 4.9 Myr for garnet growth in the Kolvik Nappe. This is approximately one order of magnitude faster than duration estimates calculated when using the apparent, lower temperature obtained from the resorbed garnet rims. Concomitantly to garnet growth in the Kolvik Nappe, garnet overgrowths formed in the Bekkarfjord Nappe for c. 2.5 Myr at metamorphic peak temperatures of c. 560˚C. The garnet growth durations obtained in this work are comparable with the uncertainty on the Lu–Hf garnet–whole-rock isochron ages published previously for the studied rocks (Gaidies et al., 2022). The results provide new insight into the timescales of repeated Barrovian-type metamorphic events experienced by the lower nappes of the Kalak Nappe Complex during the final stages of the Caledonian Orogeny in Arctic Norway.Reference: Gaidies, F., Heldwein, O. K. A., Yogi, M. T. A. G., Cutts, J. A., Smit, M. A., Rice, A. H. N. (2022). Testing the equilibrium model: An example from the Caledonian Kalak Nappe Complex (Finnmark, Arctic Norway). Journal of Metamorphic Geology, 40(5):859–886.
Assessing the Role of Outburst Floods in the Formation of the Lower St. Croix River Valley, MN/WI, USA
Authors: Delikowski Hunter , Uchytil Grace , Rowen Jayda , Fischer Abigail , Larson Phillip , Johnson Mark , Faulkner Douglas , Running Garry , Rittenour Tammy , Wickert Andrew , Brown Andy , Hilgendorf Zachary , Schirmer Ronald
Published: March 2024

A burgeoning theme of research has focused on overflow and outburst flood events in reorganizing drainage basins, creating new fluvial landscapes and transverse drainages. Generalized conceptual ideas may not fully grasp the complexity of real proglacial and deglacial landscapes, making these landscapes important to examine. The St. Croix River valley (SCRV), MN/WI, USA, and its drainage basin contain well understood glacial geology, and the complex evolution of SCRV is largely the result of dyssynchronous advance and retreat of the Superior Lobe and Grantsburg Sublobe through the SCRV basin. Several proglacial lakes formed in and surrounding the SCRV, including Glacial Lake Duluth (GLD) in the Superior basin and Glacial Lake Grantsburg (GLG) at the margin of the Grantsburg Sublobe. Prior research identified multiple high-magnitude meltwater flood spillways that drain into the SCRV that formed between ~22–10.6 ka. However, these floods are not well constrained in terms of process, magnitude, and timing. Thus, the landscape evolution of the SCRV fluvial system remains poorly understood.We focus on a specific reach of SCRV through which all high-magnitude meltwater discharge was routed. This reach contains numerous terraces, abandoned paleovalleys, a transverse reach and bedrock canyon, and an anomalously high and extensive terrace-like surface called the Osceola Bench (OB). We compile pre-existing data and add ground penetrating radar (GPR) data, describe sediments extracted with hand augers and a Geoprobe, date sediments with optically stimulated luminescence (OSL), and interpret sediment geochemistry using X-ray fluorescence (XRF). In addition, we map landforms using LiDAR DEMs and aerial imagery. We identify alluvial terraces and paleovalleys that step down from the OB towards the modern river. GPR results from OB and adjacent terraces reveal a horizontally continuous and shallow (