bluuebunny/crossref_metadata_2025 huggingface dataset:
Future Terrestrial Water Reserves to Undergo Stronger Interannual Variability
Authors: zhu jinyu
Published: March 2024

Total water storage (TWS), as an important part of terrestrial water cycle, is crucial for evaluation of water resources availability over land, which has been shown experiencing severe water crises with increasing occurrence of extreme hydrological events (e.g., droughts) under global warming. While various studies have investigated the long-term mean/trend of TWS, variation of future interannual variability (annual variance; IAV) of TWS and its influencing components are still unclear. In this study, we analyze the trend of interannual variability of TWS (IAVT) from history to the future (1850-2099) in different scenarios and quantify how IAVT is influenced by changes in TWS components (including canopies water CW, groundwater GW, soil moisture SM, surface water SW, and snow water equivalent SWE) over global land using hydrological model simulations. Results show that under both Rcp2.6 and Rcp6.0 scenarios, more than 50% of the terrestrial regions have increasing trends in IAVT, which is mainly influenced by climate change, with limited impacts from human activities and land use change. Note that the trend of increasing IAVT is especially strong in the Amazon, India, and the North China Plains region of China. Based on the principle of variance decomposition, the IAVT is decomposed into different components to quantify their impacts separately. Results show that there are significant regional differences in the dominant factors of IAVT, for instance, the high IAVT in India, North Australia and the North China Plain is dominated by the IAV of GW, while the IAVT at high latitudes of the Northern Hemisphere is primarily controlled by the IAV of SWE. Interestingly, impact of SWE (GW and SW) on IAVT is shown weakened (strengthened) in the future, which may be caused by reduction of snowfall rates and increase of snowpack melting due to warming leading to a (an) decrease (increase) in surface SWE (SW and GW). The above results emphasize the important impacts of climate change on IAVT, as well as divergent importance of different components on future IAVT changes, which can help to cope with water scarcity and hydrological extremes in the context of climate change. 
Inequality in the exposure to air pollution and temperature through the century
Authors: Pozzer Andrea , Chowdhury Sourangsu , Ma Lin , Steffens Brendan
Published: March 2024

Air quality and surface temperature exert significant influences on human health. However, the impact of air pollution and non-optimal temperature is not uniformly experienced across the population. In this study, we employ the "Gini" coefficient, a commonly used concept in economics. While traditionally applied to represent wealth inequality, we adapt this coefficient to gauge spatial inequality in population exposure to air pollutants and temperature, irrespective of the economic income of the population. As pollution and temperature are dynamic and subject to change in the future due to varying climate change and socioeconomic scenarios, our analysis extends to potential scenarios projected by the Coupled Model Intercomparison Project (CMIP6). We show changes of the Gini coefficient both at global, regional and country scale for the present century (2000-2100) covered by the model simulations. Our findings indicate that at global level, air quality inequality has peaked around the present time, with a trend towards decreasing inequality in most projections, reaching a minimum by the end of the century. Conversely, temperature exposure inequality will fluctuate based on the scenario, primarily showing an increasing inequality trend over time in alignment with anticipated climate change impacts. Importantly, the Gini coefficient estimation provides a complementary view to air quality and climate change assessment, indicating exposure disparities among the population in a specific region. Our study shows the unequal distribution of air quality and temperature exposure among populations, emphasizing the need for targeted interventions and policies to address these disparities, especially considering the projected changes in climate and socioeconomic factors.
The interconnections between household energy, health, and climate change: a comprehensive umbrella review
Authors: Marggraf Clemens , Huang-Lachmann Jo-Ting
Published: March 2024

Household energy is becoming increasingly important for the maintenance of good health, especially as people spend 90% of their lifetime indoors. However, there are a number of health and climate impacts associated with the generation and use of household energy. To date, there is no holistic picture in the literature describing the interlinkages between household energy, health outcomes and climate change. In order to systematically synthesize the fragmented evidence, an umbrella review will be conducted.
Therefore, a systematic review of peer-reviewed literature was carried out following PRISMA guidelines. Five electronic databases were searched (PubMed, Web of Science, Google Scholar, Cochrane and Scopus) to assess available literature on climate change, health and household energy, from January 1, 1900 through to June 5, 2023.
Preliminary findings highlight the dynamic interactions between the three issues, e.g., the impact of climate change on energy use/production and health outcomes, as well as the impact of different methods of energy use/production on climate change and health outcomes. In addition, the lack of consideration of the current literature on climate change  in the context of health and energy is a further finding of the umbrella review. Furthermore, the literature reviewed tends to ignore inclusion criteria (e.g., gender, socioeconomic or spatial aspects), which are also essential for a just transition to a more climate-friendly society in the future.
The goal of the umbrella review is to help policymakers understand the complex interrelationships between the three topics, both now and in the future, as climate change progresses and humanity is forced to adopt different mitigation and adaptation methods that affect energy use and production, as well as health outcomes.
Greenhouse gas emissions from drainage ditches and irrigation canals
Authors: Silverthorn Teresa , Evans Chris , Peacock Michael
Published: March 2024

Drainage ditches and irrigation canals are widespread across the globe, and have a high potential to emit greenhouse gases (GHG) to the atmosphere, contributing to climate change. Often located in agricultural or urban areas, ditches may receive high inputs of organic matter and nutrients, thereby stimulating GHG production. Previous work (Peacock et al., 2021) has calculated the global magnitude of methane emissions from ditches (~1% of all anthropogenic methane emissions). However, the relative contributions of carbon dioxide and nitrous oxide remain unknown at national and global scales, although field studies show emissions of these GHGs can be large. As anthropogenic features, GHG emissions from ditches must be reported to the United Nations Framework Convention on Climate Change under Intergovernmental Panel on Climate Change (IPCC) protocols, but current guidelines only exist for methane (in the 2019 Refinement). Here, we present the results of an (ongoing) review where we collate existing scientific literature to synthesize carbon dioxide and nitrous oxide emissions data from ditches and canals around the world, as well as identifying the principle driving variables. The results of this research will help inform IPCC guidelines for improved GHG emission accounting, and reveal if ditches and canals act as hotspots of non-methane GHGs.
Projected future changes of very extreme precipitation events over central European river catchments from ensemble climate simulations
Authors: Ruff Florian , Pfahl Stephan
Published: March 2024

Extreme precipitation events can cause flooding in central European river catchments. Climate simulations show that extreme precipitation, especially towards longer return periods, will intensify in a warmer climate for most parts of Europe. In order to study the mechanisms leading to the intensification of particularly extreme events, we investigate 10-year daily precipitation events over five major central European river catchments in Community Earth System Model Large Ensemble simulations. A statistical evaluation and comparison of large-scale circulation patterns associated with the events with operational ensemble weather prediction data from the ECMWF indicate a realistic representation of the 10-year extreme events in the climate model. Differences in these circulation patterns are analysed between the historical climate of 1990-2000 and a warmer climate at the end of the century (2091-2100). While most events occur in the core summer months (June-August) in the historical climate, there is a broadening of the seasonal distribution with extreme events from May to October in the warmer climate. Precipitation rates increase locally by 5-7%/K, similar to the Clausius-Clapeyron rate, related to significant increases in lower-tropospheric humidity. Averaged over the entire catchments, precipitation still increases, but with lower intensification rates varying between 1.2 and 3.8%/K for the individual catchments. This is due to a combination of thermodynamic and dynamic factors, in particular the shift towards the cold season, associated with smaller temperature increases during the events than expected from the overall warming, and a weakening of vertical motion over parts of the catchments. In future research, the robustness of these findings should be investigated through comparison with other climate simulations.
Different strategies of the catchment division in the process of multi-objective calibrating the conceptual rainfall-runoff model
Authors: Aleksić Milica , Kubáň Martin , Szolgay Ján , Párajka Juraj
Published: March 2024

While the familiar path of experimenting with multi-objective calibrating a conceptual rainfall-runoff model involves the whole catchment area, this study examines and compares various spatial divisions of the catchment during the calibration process. The input data that is used includes runoff values (Q), precipitation (P), air temperature (T), and potential evapotranspiration (PET). Additionally, values of soil moisture obtained by the sensors of the remote sensing source (advanced scatterometer (ASCAT) remote sensing product-ASCAT SWI) were also incorporated into the analysis within a selected catchment in Slovakia. This study provides insights into the best practices for integrating satellite soil moisture data into multi-objective calibration. Moreover, including satellite soil moisture data is particularly significant, offering a novel perspective on moisture dynamics within the catchment. One of the objectives of this research is to identify the optimal spatial division of the catchment, explicitly evaluating the effectiveness of elevation-based division versus land cover-based division. These different catchment subdivisions should point to the impact on the accuracy and reliability of the rainfall-runoff model. The calibration strategy chosen for this study is divided into the period from 2007 to 2014 for the calibration run and for the validation run chosen period from 2015 to 2019. First results show improvement of soil moisture correlation results in land cover-based division contrary to elevation zone subdivision, in the whole period of calibration (2007-2014), as well as in only summer months period (June, July, August and September). Different established calibration strategies should offer a robust framework for calibrating the rainfall-runoff model in future.AcknowledgementThis study was supportedby the VEGA Grant Agency No. VEGA 1/0577/23.
Near-Surface Geophysical Investigation of Historic Mines in Ore Mountains, Czechia
Authors: Beránek Roman , Mrlina Jan , Klanica Radek , Vošvrdová Eliška
Published: March 2024

Keywords: Historic mines, Near-surface geophysics, Montan-archaeology, Mining heritageThe Ore Mountains are known for a considerable number of mineral deposits that have played an important role in the development of human activities at least from the early Bronze Age to recent times. This long period of prospecting and mining led to the creation of a unique mining landscape, recognised today as a UNESCO World Heritage Site. The underground mining relics, which have often been disused for hundreds of years, are an interesting target for mining archaeology and can often be converted into a mining museum. Many historic mines have an uncertain or unknown location, which, combined with the complicated relief of the mining landscape, makes excavation and further investigation a challenge. In one of the tin mining districts in the village of Hřebečná, we have investigated several sites where shallow mines from the early modern period are suspected, using a range of near-surface geophysical methods, the evaluation of historical sources, and terrain analysis. We have used microgravity survey in combination with electrical resistivity tomography and ground penetrating radar. We describe the entire process from the planning phase, including the evaluation of prior historical and geological knowledge, through to processing of observed field data. Then we discuss general capabilities of each geophysical method for the detection of voids in different states of preservation. Special attention is paid to complex interpretation in the case of conflicting results from different methods and to the determination of the most likely locations of the structures. In addition, we examine the possibility of creating density models through different modelling strategies and the reliability of models in case of significant measurement errors. The modelling includes forward modelling of the response from different scenarios with added noise according to our measurement error to estimate the detection chances for the empty, partially filled and filled mining adit, as a feasibility study, and interpretation modelling based on observed data as well.
X-ray CT characterisation of dune sands to inform geomorphological models
Authors: Fox Bethany , Tawfik Ahmed , Armitage Oliver , Einsle Josh , Smyth Thomas
Published: March 2024

Coastal sand dunes are a key feature of coastlines worldwide, performing a number of functions in the landscape. They act as important coastal defences, reduce beach erosion, and provide habitats for a number of endangered species. Dune morphology and location are controlled by deposition and erosion by aeolian (wind) processes, and these processes are of great interest to geomorphologists, ecologists, and land managers.In dune sand transport models, sand grain density is assumed to be a constant 2.65 g cm-3, the density of quartz, as this is the most common sand-forming mineral in most beaches. However, many beach sands also include a proportion of denser minerals such as ilmenite (~4.7 g cm-3) or magnetite (~5.17 g cm-3). Although such minerals generally form a relatively small proportion of the overall composition, they may become concentrated at the surface, leading to local regions with a substantially higher proportion of heavier grains. The effect of this on wind threshold speeds required to erode dune surfaces is unknown.We sampled transects of dune surfaces with higher concentrations of heavy minerals at the Ainsdale National Nature Reserve in Formby, Northwest England. Samples were scanned using a Nikon MCT X-ray CT at a resolution of ~5.7 microns voxel size. Density distributions of grains at the surface of the samples were compared with deeper levels within the sample, with a control sample and with other samples in the transects. Several transect samples were found to have denser grains at and near the surface compared with the overall distribution and with the control, as well as dense layers within the sample perhaps representing inactive buried dune surfaces. Characterisation of the mineralogy of the sand and correlation with the CT scans will allow us to quantify the density variation at the surface in different locations and provide more realistic input parameters for sand transport modelling. 
Spatial-temporal changes of the long-term average monthly runoff in Slovakia
Authors: Sabová Zuzana , Kohnová Silvia , Liová Anna
Published: March 2024

This study aims to analyse the changes in the long-term average monthly runoff regime on the territory of Slovakia. For the analysis, the average monthly discharges from 57 gauging stations of the whole territory of Slovakia, which the Slovak Hydrometeorological Institute provided for the period 1961-2020, were used. The selected basin areas range from approximately 10 km2 to 1000 km2. The monthly discharge data available were divided into two periods: the old one, 1961-2000, and the new reference period, according to the World Meteorological Organization (WMO), from 1991 to 2020.  The appropriate number of clusters was determined according to the statistical analysis using the average Silhouette Width and the Elbow method. Subsequently, the PCA method and K-means clustering were performed to pool the catchments into groups. The results present the outputs of the particular runoff regime in the selected gauging stations divided into five clusters. South-central Slovakia and central Slovakia characterise Cluster No. 1; Cluster No. 2 by the northwest and northeast of the country; Cluster No. 3 for the centre of northern Slovakia; Cluster No. 4 for central Slovakia, and Cluster No. 5 for the east, south and west part of Slovakia. When comparing the changes in the regime of both periods, we can state that the best, 89% agreement was in Custer No.2, representing the High Tatras region, and 86 % agreement was in Cluster No.5 for the western part of Slovakia, with is 44% in Custer No.4, where the highest long-term average monthly flows remain in April, but the lowest normalized long-term average monthly flows shift from January to February. In Custer No.3, with 40 % agreement of catchment forming the clusters, we find a similar shift of peak long-term average monthly flows from April (1961-2000) to March (1991-2020). The most significant changes in the long-term average monthly runoff regime were found for the catchment in Cluster No.1.Finally, the most important characteristic features of the individual clusters of gauging stations created were also analysed, which could help incorporate other catchments into appropriate regional types in the future. The methodological procedure developed could also be used in further studies to predict future flow regime changes on the territory of Slovakia.AcknowledgementsThis study was supported by the Slovak Research and Development Agency under Contract No. APVV-20-0374 and VEGA Grant Agency No 1/0782/21. The authors thank the agencies for their research support.
Using X-ray Fluorescence and Absorption Spectroscopy to Investigate Redox-Sensitive Metals in Late Cretaceous Pedogenic Carbonate Nodules
Authors: Lesko Anna , Rasbury Troy , Tappero Ryan , Northrup Paul , Barker Amanda , Dworkin Steve
Published: March 2024

Synchrotron-based X-ray absorption spectroscopy (XAS), in the context of X-ray florescence (XRF) maps, is a powerful analytical tool that can define element speciation and characterize the local atomic structure of a suitable sample. While this type of analysis is regularly used to provide advances in a variety of scientific fields, including but not limited to material sciences, molecular physics, and medical sciences, it remains an underutilized tool in the (paleo)geosciences.  Here, we show that XAS can advance our knowledge of the Critical Zone in deep time. For this study, we used the X-ray fluorescence microprobe (XFM) beamline above the uranium (U) LIII-edge to create detailed XRF elemental maps. Based on these maps, we used X-ray absorption near edge spectroscopy (XANES) to probe U and Manganese (Mn) speciation of pedogenic carbonate nodules collected from Late Cretaceous paleosols from Big Bend National Park, Texas, USA.Pedogenic carbonate nodules are derived from soil waters that are oversaturated with respect to calcite. Accumulation of pedogenic calcite primarily occurs in semi-arid environments with mean annual precipitation ranging from 500-1200 mm/yr. Nodules are commonly used for uranium/thorium (U/Th) dating, atmospheric CO2 concentration(pCO2) reconstruction, and weathering intensity reconstruction using major and trace element concentrations. As prevalent as nodule research is in these various geological applications, little is known about the compositional variation on a microscale. We present and elucidate the texture, grainsize, and redox-sensitive elemental heterogeneity found within and between carbonate nodules. Preliminary results from U LIII-edge and Mn K-edge XANES showed primarily oxidized U and Mn.  XRF mapping of the samples indicate element discrimination between different carbonate fabrics as well as element zoning. The methods utilized in this study enable us to understand not only the microscale geochemistry of pedogenic carbonate nodules, but to provide an example of how XAS can be beneficial and useful for the paleoclimate and petrography community.
Global glacier climate disequilibrium from modelling steady state AAR
Authors: Yang Weilin , Chu Wenchao , Li Yingkui , Mackintosh Andrew
Published: March 2024

Most glaciers and ice caps (GIPs) are out of balance with the current climate, exhibiting continuous retreat and thinning. These changes impact regional runoff and contribute to sea level rise, causing glacier-related hazards. In this study, we estimate the area and volume losses for current GIPs to reach equilibrium through modelling the steady state accumulation area ratios (AAR0) and time-averaged AAR of each GIP. The modelled global average AAR0 is 0.541 ± 0.082, which is lower than most previous studies due to the inclusion of numerous unobserved GIPs. Ice caps exhibit a higher AAR0 (0.612 ± 0.11) compared to glaciers (0.538 ± 0.08). For regional distribution, the largest AAR0 appears in northern Arctic Canada (0.608 ± 0.114) and low latitude areas (0.570 ± 0.067), while the smallest AAR0 occurs in Central Europe (0.519 ± 0.066) and north Asia (0.522 ± 0.071). Accounting for debris-cover reveals a decrease in AAR0 due to reduced sub-debris melting, while considering the frontal ablation of marine-terminating glaciers leads to an increase in AAR0. Assessing the imbalance between global GIPs and the current (2000-2019) climate, we project an additional loss of 23 ± 6% in area and 29 ± 8% in volume. This corresponds to a sea level rise equivalent of 128 ± 34 mm. The Antarctic and subantarctic are the primary contributor to global mean sea level rise, accounting for 60 ± 20 mm. The GIPs in central and eastern Himalaya, as well as the Mt. Hengduan exhibit significant instability, characterized by an average imbalance ratio (AAR/AAR0) of 0.72 ± 0.25.
Reducing nitrogen losses in agriculture: integrated modelling of fertilizer and climate change scenarios in Austria 
Authors: Jost Elisabeth , Schönhart Martin , Mitter Hermine , Zoboli Ottavia , Schmid Erwin
Published: March 2024

The European Commission has initiated the Green Deal aiming to make the European Union climate-neutral by 2050, with the Farm to Fork strategy being one of its components. Apart from making food systems fair, healthy and eco-friendly, the Farm to Fork strategy targets to reduce nutrient losses and fertilizer use. Previous research has criticized the strategy for its expected negative impacts on European economy, agriculture, and food supply. We add to this research by using an integrated modelling framework to assess the impacts of fertilizer and climate change scenarios on agricultural production and the environment in Austria. The integrated modelling framework consists of the crop rotation model CropRota, the biophysical process model EPIC, and the spatially explicit bottom-up economic land use optimization model BiomAT. Besides other bio-physical and economic datasets, we employ national nitrogen-balance calculations to differentiate between regional and crop specific fertilization intensities as well as mineral and organic fertilizers. We have developed two fertilizer scenarios: a f20 scenario, which considers a uniform 20% reduction of mineral N fertilizer on cropland and grassland, and a fcm scenario, which combines several fertilizer restrictions such as -20% of mineral N fertilizer, a maximum application of 175 kg N ha-1 on cropland and grassland, and no mineral N fertilizer application on permanent grassland. In addition, we consider four climate change scenarios to support systematic analysis of potential effects of fertilizer reductions on land cover/use, fertilization intensities, potentially harmful nitrogen losses in air, water and soil sediments, and agricultural output. Our scenario results show a total reduction of N losses in air, water and soil sediment by 9% (f20) and 20% (fcm), yet imposed restrictions fall short of an intended 50% reduction. N loss reduction potentials are region, land cover/use and management specific. Magnitudes of N input reductions correspond well to potential N loss reductions to air. N losses to water and soil sediment seem to be determined by precipitation, temperature, and topographic factors. We conclude that agricultural measures need to be tailored to regional and topographic factors in order to effectively reduce nitrogen losses.
Impact of fire smoke vortices on stratospheric ozone chemistry: case of the Australian fires in 2019-202
Authors: Vieille Loïc , Jégou Fabrice , Berthet Gwenaël
Published: March 2024

The 2019-2020 Australian wildfires marked a significant event characterized by an unprecedented injection of biomass burning products into the stratosphere. This study focuses on the unique atmospheric phenomena that occurred during these fires, i.e. the formation of vortex-like structures in the stratosphere which had profound effects on stratospheric chemistry.The wildfires triggered severe pyrocumulonimbus thunderstorms which propelled combustion products into the upper troposphere and lower stratosphere. These emissions could self-organize into a high vorticity anticyclonic structure, a phenomenon observed by Khaykin et al. (2020). This vortex effectively confined the mixture of gases and aerosols from biomass combustion products in the stratosphere for an extended period, leading to specific chemical reactions and interactions.This study mainly utilizes data from the Microwave Limb Sounder (MLS) and the Atmospheric Chemistry Experiment Fourier Transformer Spectrometer (ACE-FTS) to investigate the behaviour of ozone-depleting species and the impact of biomass burning products within this most striking vortex structure. The data reveal a significant increase in water vapour and biomass burning products, such as CO, CH₃Cl, CH₃CN, and HCN. Concurrently, there were marked depletions in key stratospheric chemicals like the HNO₃, ClONO₂ and HCl reservoirs with an increase of the ClO radical as an indicator of chlorine activation over the lifetime of the vortex i.e. until 3 months starting in early January 2020.The core objective of this study is to elucidate the specific reactivity of inorganic atmospheric species inside this smoke vortex which led to the formation of a localized ozone hole.  More investigations would be necessary to highlight the role of organic compounds on the observed ozone depletion.The frequency of these dynamic structures is currently not well established in a context of global warming and may follow the increasing frequency and intensity of forest fires. As a result, smoke vortices could become a recurrent and important disturbance of the stratospheric chemistry in the future.
Investigating the drivers of abrupt Antarctic sea ice decline
Authors: Chan Chun Yin , England Mark , Screen James , Bracegirdle Thomas , Blockley Ed
Published: March 2024

Antarctic sea ice cover experienced an abrupt decline in 2016, transitioning from a record maximum state to a record minimum state. However, the drivers of this rapid retreat are currently not well understood. Therefore, it is difficult to determine whether this signals the start of a long term melting trend, as has been long anticipated by climate models, or is an isolated episode of internal climate variability. In this study, we utilise the CMIP6 archive to understand if internal climate variability could be responsible for this Antarctic sea ice anomaly, and if so what the primary atmospheric and oceanic drivers are. This involves examining composites of the tropical teleconnections, subsurface ocean heat content, and high latitude atmospheric variability preceding extreme Antarctic sea ice anomalies in CMIP6 simulations. The primary objective is to elucidate the multifaceted factors influencing these extreme events, specifically addressing the 2016-2017 sea ice retreat, with lessons for 2023’s extreme Antarctic sea ice state. Initial results indicate that such events are possible in the absence of anthropogenic emissions in some climate models, although the occurrences are considered rare. We also show that that using the limited observed record alone will underestimate the interannual variability of the Antarctic sea ice cover and therefore overestimate how rare such an anomaly would be. In fact, if we extend the observed record further back using statistical reconstructions, rapid declines of sea ice extent occurred in the early and mid 20th century.  Our results highlight the importance of internal climate variability in the Southern high latitudes and advance our understanding of the drivers and predictability of Antarctic sea ice changes. We discuss the implications of this work for 2023’s record Antarctic sea ice anomaly.
Past and future Mediterranean cyclone characteristics using a regional climate model
Authors: Doensen Onno , Messmer Martina , Kim Woon Mi , Raible Christoph
Published: March 2024

Extratropical cyclones play a dominant role in the Mediterranean. They are important for local water supplies, but they can also cause severe damage due to heavy winds, extreme precipitation and coastal floods. Over the last decades, a decrease in the number of extratropical cyclones in the Mediterranean has been observed. Climate models suggest that this decreasing trend will continue in the future under global warming, leading to fewer storms and dryer conditions over the region compared to the present. However, it is much less clear how extreme cyclones in the Mediterranean will respond to climate change. Our previous study, based on a simulation from the Community Earth System Model (CESM) covering the last 3500 years, indicates that extreme cyclones show a distinct centennial variability in frequency, cyclone-related precipitation and wind speed. In addition, we found a weak relation between atmospheric circulation modes and varying cyclone characteristics across different regions in the Mediterranean. However, the coarse horizontal resolution of CESM (2.0°×2.5°) is not very well suited to resolve the mesoscale cyclones that often occur in the Mediterranean. For this study, we downscaled the CESM simulation for the period 1821–2100 (RCP8.5 scenario from 2005 onwards) to a horizontal grid resolution of 20 km using the Weather Research and Forecasting (WRF) model. The WRF simulation can resolve the cyclone characteristics in the Mediterranean more accurately than CESM. Additionally, the WRF simulation is able to reproduce the complexity of cyclone-related wind speed and precipitation in a much more detailed way. Preliminary results show a strong decrease in cyclone frequency as a result of global warming. However, this trend is much less clear for extreme cyclones with respect to wind speed and precipitation. Using the long downscaled WRF simulation, we intend to identify characteristics in CESM that lead to extreme wind and precipitation in the downscaled simulation. Additionally, we will investigate the most extreme wind and precipitation events in the Mediterranean to understand what processes are better captured at smaller scales than in the global model.
Evaluating Mg(OH)2 as an ocean alkalinity agent in tropical river, estuary and saline water
Authors: Wang Xuechao , Shi Jiajia , Huang Xin , Bai Ruqin , Qi Yifan , Niu Ruoyu , Hopwood Mark
Published: March 2024

Ocean Alkalinity Enhancement (OAE) is a proposed mechanism of atmospheric CO2 removal, or negative emission technology. The addition of mineral particles to natural waters is one potential method of achieving OAE, yet there are substantial uncertainties concerning the efficiency of this process in terms of total alkalinity (TA) generation under natural conditions. Laboratory incubations are generally conducted under standardized conditions with filtered, deionized or sterile water which, whilst necessary to conduct reproducible mechanistic studies, is clearly not representative of most natural waters in which OAE might be deployed. In order to assess how variation in natural water properties affects the dissolution of minerals proposed as OAE agents, here we test the conversion of Mg(OH)2 to total alkalinity (TA) in river water, estuarine water, coastal seawater and offshore seawater. We found that when added as milk of magnesia, a 10 g/L (final concentration) Mg(OH)2 dose was efficiently converted to TA (>95% efficiency) in river water with low initial TA (mean TA = 239.44), river water with medium initial TA (mean TA = 1636.13), high salinity estuarine water (salinity 27), low salinity estuarine water (salinity 5.3), and seawater. However, when Mg(OH)2 was applied to high TA river water as a single dose (10 mg/L), the TA increase was only 60% of the calculated addition. The effect of multiple small doses (2.5 mg/L) was also tested, with no significant difference in the TA conversion in most cases. Dry additions of Mg(OH)2, rather than pre-mixed suspensions of milk of magnesia, were found to be inefficient TA sources, sometimes leading to negative TA changes- especially when using small incubation bottles (2 L). Overall it was demonstrated that Mg(OH)2 can be used as an efficient TA source in most natural waters for final doses in the range 2.5-10 mg/L.
Physical parameters of peat and other organic soils can be derived from properties described in the field
Authors: Dettmann Ullrich , Tiemeyer Bärbel , Heller Sebastian , Piayda Arndt , Schemschat Bernd , Frank Stefan
Published: March 2024

Knowledge about the bulk density and porosity of peat and other organic soils is of major importance, as both parameters directly or indirectly effect hydrological conditions (e.g., soil moisture, water level fluctuation), soil physical processes (e.g., shrinkage, swelling, subsidence) and biological processes (e.g., peat mineralization, peat growth). The agricultural usability (e.g., trafficability, plant growth, yield) and the rewetting and oscillation capacity of peatlands also strongly depend on soil hydraulic properties and, thus, on bulk density and porosity. Additionally, knowledge of bulk density is necessary to convert concentrations (e.g., soil organic carbon content) into volume-related quantities. Bulk density and porosity depend on the botanical origin of the peat, the degree of decomposition and other pedogenetic processes. These soil characteristics can be identified directly during soil examinations in the field. In contrast, the determination of bulk density and porosity requires volume-based sampling and subsequent laboratory analyses.Here, we present pedotransfer functions for peat and other organic soils to derive bulk density and porosity using random forest models. Based on a dataset from approximately 600 horizons from 100 peatland sites in Germany and other European countries, we built a set of different pedotransfer functions combining predictor variables determined in the field. These included the degree of decomposition, peat type (e.g., Sphagnum peat, Carex peat, amorphous peat), horizon characteristics (e.g., aggregated, oxidized, permanently saturated, ploughed), average horizon depth, rooting intensity (no roots to extremely dense, estimated from root proportion per cm²), admixture of mineral compounds and the occurrence of carbonate (estimated using 10% hydrochloric acid). Further pedotransfer functions were built, using soil organic carbon content as an additional predictor variable.The results show that bulk density and porosity can be predicted using only a few predictor variables (3-7) with a low bias and high coefficient of determination. Adding soil organic carbon content as an additional predictor variable further improved the pedotransfer functions. Depending on the combination of the predictor variables, root mean square errors (5-fold cross validation) varied between 0.069 to 0.099 g cm-3 for the bulk density and 3.8 to 4.7% for the porosity pedotransfer functions.
The Indian Easterly Jet During the Pre-Monsoon Season in India
Authors: Croad Hannah , Shonk Jonathan , Chevuturi Amulya , Turner Andrew , Hodges Kevin
Published: March 2024

We identify for the first time an Indian Easterly Jet (IEJ) in the mid-troposphere during the pre-monsoon season, using ERA5 reanalysis data.  The IEJ is weaker and smaller in zonal extent than the African Easterly Jet over West Africa, with a climatological location of 10°N, 60–90°E, 700 hPa, and strength 6–7 m s−1 during March–May. The IEJ is a thermal wind associated with low-level meridional gradients in temperature (positive) and moisture (negative), resulting from equatorward moist convection in the ITCZ and poleward dry convection arising due to surface heating of northern India and surrounding inland desert regions. The IEJ is associated with a negative meridional potential vorticity gradient, therefore satisfying the Charney-Stern necessary condition for instability.  However, no wave activity is detected in various metrics, suggesting that the potential for combined barotropic-baroclinic instability is not often realized. This is likely related to the small zonal extent of the jet, with insufficient time for wave growth, or the lack of upstream orography. The IEJ is found to be linked with the meteorology of pre-monsoon India. IEJ strong years feature increased near-surface temperatures and drier conditions over India, while the opposite is found in IEJ weak years. Initial investigations did not indicate strong relationships between the IEJ state and the El Nino-Southern Oscillation or the Madden Julian Oscillation, although more detailed investigations are needed to clarify this.  This study provides an introduction to the IEJ’s role in pre-monsoon dynamics, and a platform for further research. This includes identifying any links with pre-monsoon meteorological hazards (heatwaves and thunderstorms) and potential impacts on the subsequent monsoon, and understanding large-scale conditions that drive changes in the IEJ.
Interaction of biosolids-derived dissolved organic matter with microplastics: EEM analysis
Authors: Solomon Rashika , Arye Gilboa
Published: March 2024

Composted biosolids are commonly used in agricultural lands as organic amendments. However, biosolids application also exposes the soil to pollution risk from various contaminants including microplastics (MPs). The MPs inevitably interact with the dissolved organic matter (DOM), which is the most active fraction of the soil organic matter. The physiochemical properties of the DOM, which vary based on the organic matter origin, are one of the key factors influencing these interactions. The majority of studies on DOM-MP interactions employ commercially available humic and fulvic acid as the DOM source and may not accurately represent the polydisperse nature of DOM released from organic amendments used in agricultural fields. The motivation for this study stems from recognizing the knowledge gap in understanding the interaction between the naturally occurring DOM in the soil and the MPs. It is imperative to investigate these interactions to determine consequential changes in DOM composition and to evaluate the fate and cotransport with other pollutants in the soils. For this purpose, we conducted adsorption experiments with various concentrations of biosolids-derived DOMs and different MP particles. We used the Excitation-Emission matrix (EEM) obtained by fluorescence spectroscopy to study the changes in the DOM due to its adsorption on the MPs. PARAFAC modeling of the EEMs was used to identify the preferential binding affinity of distinct fluorescent DOM components to the MPs. The results of the adsorption experiment and the EEM analysis will be presented and discussed.Keywords: microplastics, dissolved organic matter, biosolids, adsorption, fluorescence spectroscopy, EEM
A unique preservation window capturing coastal-marine landscape evolution across the MIS5-4 cooling event (Late Pleistocene, North Sea Basin)
Authors: Waajen Irene , Donders Timme , Busschers Freek , Wesselingh Frank , Wagner-Cremer Friederieke , Peterse Francien , van Heteren Sytze , Plets Ruth
Published: March 2024

The Late Pleistocene MIS5 - MIS4 transition (ca. 80-70 ka) is globally known to correspond to a major cooling event accompanied by a large decline in eustatic sea level. This transition must have radically changed coastal landscapes worldwide, affecting basin shape, salinity regimes, river courses, as well as biota. Most existing records are from either local lacustrine, ice core or distal oceanic records, while dated and continuous records from coastal environments are lacking. Within the southern North Sea Basin a unique record of coupled terrestrial-marine signals exists in the deposits of the Brown Bank Formation, covering the MIS5-MIS4 transition. Here, we target the Brown Bank Formation to produce a new integrated palaeoenvironment and -climate framework for the MIS5-4 transition and show biotic and abiotic environmental response to rapid cooling in a coastal area.Multi-proxy records of lipid biomarkers, pollen, mollusk and diatom assemblages for the MIS5-4 transition in the center of the southern North Sea are combined with seismic facies determinations. The Brown Bank Formation consists of multiple facies representing multiple depositional phases around the MIS5-4 transition, and provides insights into the cooling of the terrestrial and shallow marine environments. On land, the vegetation changed from boreal forests to more open, grassland vegetation, combined with an increase in soil erosion. At the same time the shallow marine environment of the southern North Sea experienced subarctic to arctic marine conditions with a high input of soil material. These continued cool marine conditions have not been described earlier for this region and show that sea level remained high and lagged local cooling, as inferred from lipid-biomarker palaeothermometry. Assuming that this lag between sea-level and temperature change is common during cooling events, it is a potential mechanism creating sediment preservation windows during the onset of glacial intervals in shallow marine environments. Preserved records like the one presented here are valuable because they capture both the unique changes in cold marine environments, as well as informative terrestrial signals that are rarely preserved onshore.
Revising hydrothermal element fluxes at mid-ocean ridges: The role of slow and ultra-slow spreading centers regarding the global hydrothermal element budget.
Authors: Diehl Alexander , Bach Wolfgang
Published: March 2024

After nearly 50 years of research on hydrothermal circulation, the global hydrothermal on-axis element turnover is still not well constrained. Existing estimates of hydrothermal element fluxes typically invoke a basalt-hosted black smoker archetype hydrothermal vent fluid that is imposed to be responsible for the global hydrothermal cooling of oceanic lithosphere. The diversity of hydrothermal vent fluid compositions, especially to be found at slow to ultra-slow spreading mid-ocean ridges (due to varying degrees of fluid rock interaction with peridotites), has not been properly addressed yet.Here we present a study that for the first time considers the diversity of hydrothermal vent fluids by analyzing a global database of hydrothermal vent fluid compositions (MARHYS Database Version 3.0). We derive a proper weighting of these fluid types by analyzing strike lengths and substrate types of the mid-ocean ridge system and estimate the partitioning of these hydrothermal fluid types to improve quantification of hydrothermal element fluxes at mid-ocean ridges. We show that the element‑to‑energy flux ratio in peridotite-hosted (or peridotite-influenced) hydrothermal vent fluids is significantly different to the one in purely basalt-hosted fast spreading ridges. Consequently, for many compounds significantly higher (e.g. H2, CH4, Fe) or lower (e.g. H2S, CO2) element fluxes are found to be associated with hydrothermal cooling at slow- and ultra-slow spreading ridges. Our results show that, despite their lower power output (compared to fast spreading ridges), slow and ultra-slow spreading centers, with their serpentinization‑derived hydrothermal fluids, play a major role for the element transfer between the ocean crust and the ocean.
Impact of human activity and fire on vegetation, hydrology, and carbon accumulation in Mustjärve bog, Northwest Estonia (PEATFLAMES)
Authors: Roberts Harry , Andrews Luke , Amon Leeli , Heinsalu Atko , Kołaczek Piotr , Marcisz Katarzyna , Słowiński Michał , Stivrins Normunds , Veski Siim , Lamentowicz Mariusz
Published: March 2024

Peatlands are important ecosystems for carbon storage, storing an estimated 25-30% of global soil carbon despite covering just 3% of Earth’s terrestrial surface. These ecosystems are under increasing pressure due to human activity and climate change, which threaten to turn peatlands from being carbon stores to sources. Human activities such as peat draining are extremely damaging to peatland hydrology, and fire was often used by people as a tool for land management clearance in the past. Fire is one of the foremost forces impacting peatlands, as it destroys surface peat and the subsequent release of stored carbon. Fire frequency is predicted to increase due to more frequent and severe droughts in some areas, and increasing human activity in areas where peat can form (particularly in the Northern Hemisphere). These trends, if realised, can accelerate climate warming as previously stored carbon is released into the atmosphere.The focus of this study, Mustjärve bog, is an ombrotrophic peat bog located in northwest Estonia. Our project aims to assess changes in peatland fire regimes, vegetation dynamics, and hydrology to evaluate how the resilience of the site has changed over time within the context of relative changes in climate and human activity. A peat core was analysed using multiple palaeoecological proxies at high resolution (1 cm contiguous samples), to reconstruct past fire frequency, vegetation, and hydrological change over the past ~2500 years at the site. We also used historical data (population, past climate, and archaeological records) to better understand the drivers of changes uncovered in the palaeoecological record.Our data reveals a distinct anthropogenic signal from ~700 CE onwards, coincident with increasing population and expanding land exploitation. Human activity from ~700 CE to ~1800 CE causes an increase in local fire events, culminating in lowered carbon accumulation rates, lowered water tables and higher peat bulk density. This trend continued until ~1950 CE, when there was a recovery in carbon accumulation and water table depth. Mustjärve’s vegetation history was predominantly Sphagnum, with Sphagnum Sect. Acutifolia indicative of drier conditions becoming much more prevalent from ca. 200 BC onwards, possibly owing to changes in water table depth. In the last 150 years, arboreal taxa such as Pinus sylvestris and Betula nana have encroached onto the bog, reflecting a decreasing water table and increased human activity that has impacted hydrological conditions, such as peat draining. We find little evidence for a significant climate influence on Mustjärve bog, as anthropogenic pressures on the site appear to dominate over the palaeoclimatic signal.