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Mapping in situ eddy covariance measurements of terrestrial land–atmosphere fluxes to the globe is a key method for diagnosing the Earth system from a data-driven perspective. We describe the first global products (called X-BASE) from a newly implemented upscaling framework, FLUXCOM-X, representing an advancement from the previous generation of FLUXCOM products in terms of flexibility and technical capabilities. The X-BASE products are comprised of estimates of CO2 net ecosystem exchange (NEE), gross primary productivity (GPP), evapotranspiration (ET), and for the first time a novel, fully data-driven global transpiration product (ETT), at high spatial (0.05°) and temporal (hourly) resolution. X-BASE estimates the global NEE at −5.75 ± 0.33 Pg C yr−1 for the period 2001–2020, showing a much higher consistency with independent atmospheric carbon cycle constraints compared to the previous versions of FLUXCOM. The improvement of global NEE was likely only possible thanks to the international effort to increase the precision and consistency of eddy covariance collection and processing pipelines, as well as to the extension of the measurements to more site years resulting in a wider coverage of bioclimatic conditions. However, X-BASE global net ecosystem exchange shows a very low interannual variability, which is common to state-of-the-art data-driven flux products and remains a scientific challenge. With 125 ± 2.1 Pg C yr−1 for the same period, X-BASE GPP is slightly higher than previous FLUXCOM estimates, mostly in temperate and boreal areas. X-BASE evapotranspiration amounts to 74.7×103 ± 0.9×103 km3 globally for the years 2001–2020 but exceeds precipitation in many dry areas, likely indicating overestimation in these regions. On average 57 % of evapotranspiration is estimated to be transpiration, in good agreement with isotope-based approaches, but higher than estimates from many land surface models. Despite considerable improvements to the previous upscaling products, many further opportunities for development exist. Pathways of exploration include methodological choices in the selection and processing of eddy covariance and satellite observations, their ingestion into the framework, and the configuration of machine learning methods. For this, the new FLUXCOM-X framework was specifically designed to have the necessary flexibility to experiment, diagnose, and converge to more accurate global flux estimates.

Drought is a complex climatic phenomenon characterised by water scarcity and is recognised as the most widespread and insidious natural hazard, posing significant challenges to ecosystems and human society. In this study, we propose a new daily based index for characterising droughts, which involves standardising precipitation and/or precipitation minus potential evapotranspiration (PET) data. The new index proposed here, the generalised drought index (GDI), is computed for the entire period available from the Iberian Gridded Dataset (1971 to 2015). Comparative assessments are conducted against the daily Standardised Precipitation Index (SPI), the Standardised Precipitation Evapotranspiration Index (SPEI), and a simple Z-Score standardisation of climatic variables. Seven different accumulation periods are considered (7, 15, 30, 90, 180, 360, and 720 d) with three drought levels: moderate, severe, and extreme. The evaluation focuses mainly on the direct comparison amongst indices in terms of their ability to conform to the standard normal distribution, added value assessment using the distribution added value (DAV), and a simple bias difference for drought characteristics. Results reveal that the GDI, together with the SPI and SPEI, follows the standard normal distribution. In contrast, the Z-Score index depends on the original distribution of the data. The daily time step of all indices allows the characterisation of flash droughts, with the GDI demonstrating added value when compared to the SPI and SPEI for the shorter and longer accumulations, with a positive DAV up to 35 %. Compared to the Z-Score, the GDI shows expected greater gains, particularly at lower accumulation periods, with the DAV reaching 100 %. Furthermore, the spatial extent of drought for the 2004–2005 event is assessed. All three indices generally provide similar representations, except for the Z-Score, which exhibits limitations in capturing extreme drought events at lower accumulation periods. Overall, the findings suggest that the new index offers improved performance and comparatively adds value to similar indices with a daily time step.

Inland saline lakes play a key role in the global carbon cycle, acting as dynamic zones for atmospheric carbon exchange and storage. Given the global decline of saline lakes and the expected increase of periods of drought in a climate change scenario, changes in their potential capacity to uptake or emit atmospheric carbon are expected. Here, we conducted continuous measurements of CO2 and CH4 fluxes at the ecosystem scale in an endorheic saline lake of the Mediterranean region over nearly 2 years. Our focus was on determining net CO2 and CH4 exchanges with the atmosphere under both dry and flooded conditions, using the eddy covariance (EC) method. We coupled greenhouse gas flux measurements with water storage and analysed meteorological variables like air temperature and radiation, known to influence carbon fluxes in lakes. This extensive data integration enabled the projection of the net carbon flux over time, accounting for both dry and wet conditions on an interannual scale. We found that the system acts as a substantial carbon sink by absorbing atmospheric CO2 under wet conditions. In years with prolonged water storage, it is predicted that the lake's CO2 assimilation capacity can surpass 0.7 kg C m2 annually. Conversely, during extended drought years, a reduction in CO2 uptake capacity of more than 80 % is expected. Regarding CH4, we measured uptake rates that exceeded those of well-aerated soils such as forest soils or grasslands, reaching values of 0.2 µmol m−2 s−1. Additionally, we observed that CH4 uptake during dry conditions was nearly double that of wet conditions. However, the absence of continuous data prevented us from correlating CH4 uptake processes with potential environmental predictors. Our study challenges the widespread notion that wetlands are universally greenhouse gas emitters, highlighting the significant role that endorheic saline lakes can play as a natural sink of atmospheric carbon. However, our work also underscores the vulnerability of these ecosystem services in the current climate change scenario, where drought episodes are expected to become more frequent and intense in the coming years.

The World Wide Lightning Location Network (WWLLN) operates a distributed network of stations which detect lightning signals at a planetary scale. Very high currents from lightning strokes radiate strong very low frequency signals in the 6–22 kHz band, which are detected up to 10 000 km away by the WWLLN stations and which are used to determine the time and position of the lightning stroke detected by triangulation, similarly to global positioning systems. Studies of the performance of the WWLLN in different areas around the world have already been reported in the literature, but similar studies for west European regions are still unavailable. This work presents a study to determine the detection efficiency and location accuracy of the WWLLN over Spain by comparing its data with those of the Spanish State Meteorological Agency, AEMET, during 2012 taken as the ground truth. The study provides a detection efficiency for the WWLLN of around 29 % and a location accuracy of between 2 and 3 km. The efficiency for high-energy strokes is considerably higher. A study of four subregions with different geographical features is also considered. The peak current distribution of lightning events in these regions is obtained, and a possible link to the WWLLN performance is discussed. Finally, an application of the WWLLN data for three major storms in 2020, 2021, and 2022 in the Mediterranean area of Spain demonstrates that the WWLLN is well suited for tracking the time evolution of adverse meteorological phenomena.

This study examines the characteristics (magnitudes, trends, and frequency of occurrences) of extreme floods in Nepal, a country that is at significant risk from floods. Daily discharge data from 1980 to 2015 of three gauging stations (Chisapani of Karnali Basin, Devghat of Narayani Basin, and Chatara of Koshi Basin) were used to assess the largest 1 % of flows, the annual top five high flows, and floods of different return periods (2-, 5-, 10-, 20-, and 100-year). In addition, temporal trend analysis of the flood peaks was carried out using the Mann–Kendall test and Sen's slope estimates. Results show that the magnitudes of the largest 1 % flows range from 6310 to 17 900, from 6967 to 12 100, and from 6080 to 9610 m3 s−1 at Chisapani, Devghat, and Chatara, respectively. The monsoon, especially from mid-June to early September, consistently witnesses over 90 % of 1 % extreme flows, with August registering more than 51 % of these occurrences. July and August combine for 81 % of the top five flow events, predominantly in August. Despite insignificant flow changes at a 95 % confidence level, extreme floods (2-, 5-, 10-, 20-, and 100-year return periods) are concentrated heavily in July and August, with August's second fortnight recording the most flood events. This assessment emphasizes July and August as critical months for extreme floods, aiding Nepalese authorities in planning dynamic resource allocation, disaster response, and effective flood management.

Climate change is rapidly altering Himalayan glaciers, jeopardizing downstream water resources. This study investigates the impact of changing air temperatures, precipitation, and glacier configurations on streamflow in the Langtang River basin, a vital Himalayan basin. Using a process-based glacio-hydrological model driven by bias-corrected reanalysis data, we simulate streamflow under various scenarios. Results reveal that, while current glacier conditions show increased runoff with higher temperatures and precipitation, future deglaciation scenarios project a decrease in total streamflow, highlighting the complex interplay between climate and glacier dynamics in basin hydrology. These findings emphasize the need for adaptation strategies to ensure water security in the face of evolving Himalayan hydrology.

Ocean liming has gained attention as a potential solution to mitigate climate change by actively removing carbon dioxide (CO2) from the atmosphere. The addition of hydrated lime to oceanic surface water leads to an increase in alkalinity, which in turn promotes the uptake and sequestration of atmospheric CO2. Despite the potential of this technique, its effects on the marine ecosystem are still far from understood, and there is currently no information on the potential impacts on the concentration and quality of dissolved organic matter (DOM), which is one of the largest, most complex and yet least understood mixtures of organic molecules on Earth. The aim of this study is to provide the first experimental evidence about the potential effects of hydrated lime addition on DOM dynamics in the oceans by assessing changes in its concentration and optical properties (absorption and fluorescence). To investigate the effects of liming on DOM pools with different concentrations and quality, seawater was collected from two contrasting environments: the oligotrophic Mediterranean Sea, known for its dissolved organic carbon (DOC) concentration comparable to that observed in the oceans, and the eutrophic Baltic Sea, characterized by high DOM concentration mostly of terrestrial origin. Hydrated lime was added to both waters to reach pH values of 9 and 10. Our findings reveal that the addition of hydrated lime has a noticeable effect on DOM dynamics in both the Mediterranean Sea and Baltic Sea, determining a reduction in DOC concentration and a change in the optical properties (absorption and fluorescence) of DOM. These effects, detectable at pH 9, become significant at pH 10 and are more pronounced in the Mediterranean Sea than in the Baltic Sea. These potential short-term effects should be considered within the context of the physicochemical properties of seawater and the seasonal variability.

The Glacio-hydrological Degree-day Model (GDM) is a distributed model, but it is prone to uncertainties due to its conceptual nature, parameter estimation, and limited data in the Himalayan basins. To enhance accuracy without sacrificing interpretability, we propose a hybrid model approach that combines GDM with recurrent neural networks (RNNs), hereafter referred to as GDM–RNN. Three RNN types – a simple RNN model, a gated recurrent unit (GRU) model, and a long short-term memory (LSTM) model – are integrated with GDM. Rather than directly predicting streamflow, RNNs forecast GDM's residual errors. We assessed performance across different data availability scenarios, with promising results. Under limited-data conditions (1 year of data), GDM–RNN models (GDM–simple RNN, GDM–LSTM, and GDM–GRU) outperformed standalone GDM and machine learning models. Compared with GDM's respective Nash–Sutcliffe efficiency (NSE), R2, and percent bias (PBIAS) values of 0.80, 0.63, and −4.78, the corresponding values for the GDM–simple RNN were 0.85, 0.82, and −6.21; for GDM–LSTM, they were 0.86, 0.79, and −6.37; and for GDM–GRU, they were 0.85, 0.8, and −5.64. Machine learning models yielded similar results, with the simple RNN at 0.81, 0.7, and −16.6; LSTM at 0.79, 0.65, and −21.42; and GRU at 0.82, 0.75, and −12.29, respectively. Our study highlights the potential of machine learning with respect to enhancing streamflow predictions in data-scarce Himalayan basins while preserving physical streamflow mechanisms.

We have seen a surge in glacio-hydrological modeling efforts in the past few decades. This form of modeling is also being carried out in the Himalayan river basins, but a comprehensive high-resolution simulation software that can be effective with a limited number of hydrometeorological data is recommended. In this regard, an open-source, scalable, flexible, and distributed modeling system called PyGDM has been developed by fully coupling the Glacio-hydrological Degree-day Model with PCRaster Python software. To evaluate the potential of using this model in the Himalayan river basins, we calibrated and then validated the model for Trishuli River basin using geographical data and the existing hydrometeorological data. The tests showed a promising result with respect to the effective application of the model in the entire Himalayan region. The PyGDM source code was optimized and adapted to the process models of glacier melting and hydrological processes in Himalayan basins. It increased the speed of the simulation, made the model highly scalable to accommodate new submodels, and enhanced the flexibility of the model to ingest various types of input data and parameters. Hence, the PyGDM model strives to simulate the glacio-hydrological processes of the entire Himalayan region.

Rivers in the Himalayan and adjacent mountain regions are the lifelines of over 1 billion people and are the backbone of civilizations therein. The short gauge records of Nepal do not provide a sufficient time window to understand the natural variations in river discharge from a long-term climate perspective. By developing a network of over 100 tree-ring chronologies across Nepal, we checked their hydrological sensitivity for long-term streamflow reconstruction. This shows huge potential for long-term annual or seasonal streamflow reconstructions in different river basins of Nepal. A robust reconstruction model was developed between tree growth and streamflow, capturing 56 % of the variance in the actual data, and was used to reconstruct the March–July monthly average streamflow of Sinja Khola (river) at Diware from AD 1700 to 2013. The reconstruction revealed several dry and pluvial periods with the recent decline in the streamflow in the Sinja River. We found short- (2 to 8.7 years) to medium-term (35.2 years) periodicities in the reconstruction that are likely to be associated with climatic oscillations, such as the El Niño–Southern Oscillation (ENSO), the Atlantic Multidecadal Oscillation (AMO), and the North Atlantic Oscillation (NAO), along with the influence of local circulation patterns. Since Sinja Valley is related to the origin of the Nepali language and civilization, the information on long-term streamflow will be beneficial for water resource management in the context of rapid climate change and for preparedness for water-induced disasters in the region.

Riparian areas serve as interfaces between terrestrial and aquatic (including glaciers and glacial lakes) ecosystems, playing a crucial role in shaping landscapes, supporting flora and fauna diversity, and supporting human communities. Thus, riparian areas maintain ecological, cultural, and socio-economic resilience, enriching communities dependent on these ecosystems. Riparian areas are of great ecological value and have immense potential for tourism. However, the touristic value of riparian zones has largely remained unexplored and is confined mainly to the area of river-based recreational activities. This paper proposes “riparian tourism” as a holistic and sustainable form of tourism that encompasses both consumptive and non-consumptive forms of tourism. The exploration of the subject and the conceptualization of this potentially globally appealing form of tourism have the potential to offer entrepreneurial and touristic opportunities, especially for local communities, thereby ensuring not only ecological but also socio-economic benefits. The paper delves into creating a conceptual framework for riparian tourism, e.g. cryo-tourism. The research in this sense contributes greatly to increasing the discourse on sustainable tourism and emphasizes the urgency to incorporate tourism and conservation actions in riparian areas which are greatly impacted by the changing climate.

During the last few decades, a general increase in heavy rainfall events has been documented in many areas of the world. These events have caused changes in soil erosion rates and strongly affected the human activities in mountain areas by reducing the national income obtained from cultivated land. In this context, the use of fallout radiotracers can be an important tool for better understanding the consequences of climate change in these areas and proposing effective countermeasures in order to reduce soil loss. In this contribution, plot experiments carried out in southern Italy that involve the use of 137Cs and 210Pbex measurements were performed to estimate soil erosion rates during the last few decades. The overall results indicate an increase in soil erosion rates during the last 15–20 years and suggest the use of this technique to detect climate change in mountain areas.

Understanding the hydrology of the Himalayan region and its response to current and future climate scenarios is crucial for identifying the region's future water availability for infrastructural development. For this, the hydropower potential and the impact of future change on the hydrology of the Bheri River basin (BRb) and the Marsyangdi River basin (MRb) were analysed. The Glacio-hydrological Degree-Day Model version 2.0 (GDM V2.0), developed in the PCRaster dynamic modelling framework, was used to simulate the river runoff. Geospatial tools and different criteria were used to assess topographic features, identify suitable places for run-of-river (ROR) hydropower development, and estimate power potential. Eight scenarios with various combinations of temperature and precipitation changes were used to assess the hydropower potential. Increases in temperature by 0.5 and 1 °C (assumed for the near-term and mid-term future) and changes in precipitation of ±10 % and ±20 %, respectively, are used to conduct a sensitivity analysis for the hydropower potential. A total of 116 and 83 suitable sites were identified, and 4242 and 2823 MW power potentials were estimated in the BRb and the MRb, respectively. All the sensitivity scenarios show an increase in hydropower production, except for one with a drier scenario and less precipitation. The integration of a geographic information system (GIS) and a hydrological model helps us to understand the hydrological response to climate variables and its impact on hydropower in the Himalayan region.

In recent decades, the Tsho Rolpa glacial lake has witnessed a significant increase in its surface area. Situated in the Eastern Himalayas at an elevation of 4552 m a.s.l. (meters above sea level), this lake has drawn attention due to the potential risks of glacial lake outburst floods (GLOFs). To comprehensively study and prepare for future GLOF events from Tsho Rolpa, advanced modeling techniques were employed, utilizing the National Weather Service BREACH (NWS-BREACH) and Hydrologic Engineering Center's River Analysis System (HEC-RAS) models. The assessment included the evaluation of dam breach scenarios, especially 20 and 40 m breaches, using the NWS-BREACH model to estimate breach hydrographs. This analysis revealed peak flow rates ranging from 8198 to 26 662 m3 s−1 for the respective breaching scenarios. Additionally, considering a change in the lake area over 20 to 40 years, the peak flow ranged from 8226 to 10 662 m3 s−1 for the 20 m breach scenario. The peak flow estimates obtained from NWS-BREACH were subsequently integrated into the HEC-RAS model to simulate peak discharge and flood heights at varying distances downstream of the lake outlet. To understand the consequences of a GLOF, the impact on downstream areas was assessed through flood inundation maps, and precautionary measures are recommended.

The backwater effect can be caused by a number of factors, including the bridge's pier width and deck level. In lowland regions, the backwater effect can be particularly problematic, as it can lead to flooding and inundation of farmlands and houses. This study examines the impact of bridge structure on the backwater effect in the lowland region of Shreekhandapur, Kavre, Nepal. The study area is characterized by a hill slope and inner river valley, with a gentle river profile that results in low flow velocity and increased deposition. The study compares the backwater effect of an old demolished bridge with four piers of 1.2 m width and abutments on both sides to a new bridge with a single pier of 0.4 m width and a deck level that is 1 m higher. HEC-RAS software was used to analyse the steady flow and create a flood hazard map. The results show that the new bridge with a reduced pier width and increased deck level significantly reduces the backwater effect. The flood hazard map shows that the new bridge along with floodwalls reduces the potential hazard-prone areas by up to 50 %. The findings of this study can be applied to disaster mitigation and bridge design in lowland regions. By reducing pier width and increasing deck level, bridges can be designed to minimize the backwater effect and reduce the risk of flooding.

Snow-induced disasters pose significant risks in mountainous regions. Accurate visibility assessment is crucial for informed decision-making and disaster preparedness. This paper presents an innovative approach that integrates theoretical literature with practical application using augmented reality (AR) to address this challenge. The proposed system, named Him-Drishti, harnesses the established correlation between snowfall intensity and visibility to create a predictive model. By incorporating user-input snowfall intensity predictions, the Him-Drishti AR application dynamically overlays real-time visibility simulations onto the physical environment. Moreover, the use of smartphones further amplifies the practicality of this innovative solution, making the AR application a handy tool, even in the most challenging terrain. This intuitive visualization empowers stakeholders with a comprehensive understanding of potential risks, facilitating informed decisions and optimized disaster response strategies. Through AR visualization, stakeholders, emergency responders, and local authorities gain valuable insights into visibility conditions, enabling them to make informed decisions, take proactive measures, and allocate resources effectively. This study not only enhances the understanding of snow-related disasters but also demonstrates the capacity of AR in disaster management and risk reduction.

The development and integration of the spatial and temporal probabilities of landslides are required for complete landslide hazard mapping at any location. Under changing climate, the computation of the temporal probability of landslides with rainfall magnitude alone is inaccurate. This research proposes a framework based on copula functions to develop a landslide probability map using multi-site rainfall data by accounting for the rainfall variables of intensity and duration using a joint-probability approach. The proposed technique is used for Wayanad District, Kerala, India, considering extreme rainfall events in 2018. Firstly, the landslide susceptibility map of the district was developed using a robust random forest (RF) model. Based on regional geology, geomorphology, and climate, different regions of Wayanad have varying rainfall thresholds assessed according to the intensity and duration of the rainfall. Then, the temporal probability of landslides was developed, accounting for the intensity and duration of rainfall events using the joint-probability estimation using copula. Through the integration of the landslide spatial probability map with the temporal probability, landslide hazard maps (LHMs) for Wayanad were developed for time periods ranging from 1 to 50 years. The results of the study indicate the need for bi- or multi-variate landslide probability modeling in studies on regional landslide hazard assessments.

The present research integrates remote sensing (RS), Geographic Information Systems (GIS), and Multi-Criteria Decision Making (MCDM) techniques to identify groundwater potential zones (GWPZs) in Muzaffarpur. Various data sets and study areas were considered to contribute to groundwater availability. The groundwater potential was evaluated, and later, the GWPZ map was validated. It was further categorized into various potential zones from 2005 to 2020. High potential areas, located in gently sloping terrains conducive to high infiltration and percolation, maintained coverage of about 50% of the watershed. Poor potential zones, which represent a small fraction of the area with limited groundwater capacity, showed a consistently low proportion over the years. It highlights the impact of geological and geomorphological factors, particularly the Charnockite Gneiss Complex and sedimentary rocks of the Ganges Basin, on groundwater potential. Soil types, ranging from fine to coarse loamy, play a significant role in groundwater recharge. Rainfall and slope are crucial factors that influence groundwater potential. Higher rainfall and flatter slopes enhance groundwater recharge, emphasizing the importance of variables in assessment. ROC analysis revealed mixed validation results, with zones showing high potential, while others remained poor. It underscores the need for effective water conservation practices to improve groundwater availability.

High Mountain Asia (HMA) is undergoing unprecedented warming, affecting the cryosphere – including permafrost (frozen ground) – and leading to various hazards. However, understanding the prevalence, distribution, and dynamics of these hazards and how they respond to a changing climate is challenging. Permafrost is extensive in HMA, and China makes up a significant portion of this. The permafrost area in China is about 1.6×106 km2, 66 % of which is on the Qinghai–Tibet Plateau. However, most of the scientific literature concerning permafrost in China is published in Chinese and, hence, remains largely unnoticed by the non-Chinese-speaking scientific communities. In this article, we used a systematic review to evaluate the Chinese scientific literature on permafrost-related hazards and found that the studied areas are concentrated in certain areas, especially on the Qinghai–Tibet Engineering Corridor (QTEC). The increasing amount of literature on permafrost hazards reflects the increased impact of climate warming on infrastructure built on permafrost. Not only is permafrost affecting infrastructure; these anthropogenic disturbances themselves also have amplified the occurrence of hazards around settlements and infrastructure. The literature shows the strong relationship between latitude and elevation with permafrost thickness. The permafrost classification system and nomenclature used by Chinese scientists is different to that used elsewhere, which is a potential source of confusion and deserves attention.

Nepal annually invests millions of dollars in hydropower development, with a substantial portion of these funds allocated to civil infrastructure. Climate change, which impacts geological and hydrological conditions, poses a threat to civil components throughout hydropower project construction and operation. This causes budget overruns, project delays, and adverse consequences for society and the environment, ultimately resulting in multimillion-dollar losses. The identification of risk factors and their underlying causes, stemming from the impacts of climate change, constitutes a fundamental aspect of this study. This critical analysis primarily draws upon extensive literature reviews to pinpoint these factors (risk factors arising from climate change), emphasizing their economic and human impacts. This paper highlights the risks to run-of-river hydropower infrastructures in Nepal. The findings of the study can be used to develop and implement adaptation strategies to mitigate the risks posed by climate change to Nepal's vital hydropower sector.

Atmospheric rivers (ARs) are the primary mechanism for transporting water vapor from low latitudes to polar regions, playing a significant role in extreme weather in both the Arctic and Antarctica. With the rapidly growing interest in polar ARs during the past decade, it is imperative to establish an objective framework quantifying the strength and impact of these ARs for both scientific research and practical applications. The AR scale introduced by Ralph et al. (2019) ranks ARs based on the duration of AR conditions and the intensity of integrated water vapor transport (IVT). However, the thresholds of IVT used to rank ARs are selected based on the IVT climatology at middle latitudes. These thresholds are insufficient for polar regions due to the substantially lower temperature and moisture content. In this study, we analyze the IVT climatology in polar regions, focusing on the coasts of Antarctica and Greenland. Then we introduce an extended version of the AR scale tuned to polar regions by adding lower IVT thresholds of 100, 150, and 200 kg m−1 s−1 to the standard AR scale, which starts at 250 kg m−1 s−1. The polar AR scale is utilized to examine AR frequency, seasonality, trends, and associated precipitation and surface melt over Antarctica and Greenland. Our results show that the polar AR scale better characterizes the strength and impacts of ARs in the Antarctic and Arctic regions than the original AR scale and has the potential to enhance communication across observational, research, and forecasting communities in polar regions.

The aim of this study is to identify potential mineral deposits beneath the Southern Benue Trough of Nigeria based on apparent density mapping technique of estimating lateral rock densities from modelled gravity data. In this study, we apply the inverse density deconvolution filter to a short-wavelength gravity component in order to estimate the rock densities for mineral exploration applications and tectonic studies at the Southern Benue Trough in Nigeria. The estimated rock densities vary between 2.50 and 2.74 g/cm3, with minimum density values assigned to volcano-sedimentary deposits along the Cameroon Volcanic Line and maximum density values in the eastern and southern parts associated with mafic igneous rocks. Our gravity and density maps reveal the geometry of dominant geological structures within the study area. The density map highlights carbonate-hosted metallic elements with varying intercalations. Some of these identified mineralized zones coincide with locations of past and present producing mines. Intermediate and mafic igneous rocks as well as highly compacted and volcano-sedimentary rocks are mapped as rock-forming minerals for a mineral exploration. Hence, the obtained model of mineral-bearing rocks mainly demonstrates mechanisms of tectonic events, patterns of deformation regimes, and mineral prospectivity map of the study area.

Abstract Objectives Fully-polarimetric synthetic aperture radar (PolSAR) data contain a rich body of elementary scattering physics information that is critically valuable for a broad range of applications and scientific purposes. However, there is a lack of available high-resolution (

Abstract Serpentine minerals, either polymorphs or polytypes (mostly chrysotile, lizardite and antigorite), are hardly distinguished in ophiolitic serpentinites and serpentinized peridotite unless sophisticated mineralogical tools are applied. Among them, chrysotile has special chemical and structural characteristics, which can be used to identify and classify different modes, and accordingly as significant petrographic indicators of serpentinization in ophiolite sequences. Generally, chrysotile characterizes low-grade metamorphism and it occurs in massive serpentinites as well as asbestos veinlets traversing them. The present paper aims to characterize the different modes of chrysotile in serpenitinite and serpentinized peridotite from the Semail ophiolite at the Daftah area in the United Arab Emirates (UAE). The objectives include microscopic and chemical separation of three chrysotile modes; namely slip-fiber (most common), mass fiber (common) and cross-fiber (less common). The cross-fiber mode is considered a “spinning type” in sheared serpentinite with asbestos veinlets whereas the other two belong to “non-spinning type” in massive serpentinite being formed by a contact volume metasomatic process by replacement of olivine and pyroxene. Excess Mg from the transformation of ferromagnesian minerals into chrysotile, in the presence of additional SiO2, results in an association of cryptocrystalline talc with the chrysotile fibers. Differential thermal analysis (DTA) and thermogravimetry (TG) indicate that the process of thermal decomposition of chrysotile leads to the formation of olivine (forsterite). The infra-red (IR) absorption technique for end products of some selected samples appear to indicate that the spectra of the end products are similar and the absorption bands are assigned in the range of (1100–800 cm−1) and (700–200 cm−1) corresponding to Si–O and Mg–O vibration modes. Based on the findings of the present paper, the chrysotile serpentinization process is due to metasomatic replacement of peridotite during the ocean floor early episode and later an episode of ophiolite obduction. The chemical data focalize that the similarity in chemical behaviour of chrysotile veins implies that a close cogenetic relationship among three modes of chrysotile and removal of such major elements occurred during serpentinization; Mg, Fe and Si were removal in solution from the peridotite and precipitated in tension and shear fractures to form fibrous chrysotile and magnetite. Also, it can be concluded that the mode of occurrence and timing of chrysotile vein formation can be fitted according to the type of chrysotile mode. Cross-fiber type develops along tension fractures whereas mass-fiber type is finally developed via CO2 metasomatism. Finally, the slip-fiber type forms by a volume-for volume metasomatic process due to the replacement of olivine and/or pyroxene. In terms of time and tectonism, the different mode witnessed different metamorphic/metasomatic events and structures. Shear deformation is more likely connected to the formation of cross-fibers in NW- and NE-trending asbestos veins and veinlets.

Abstract Meteorological drought is one of the major natural hazards that affects the ecosystem of the Central Indian state of Chhattisgarh. This study delves into the analysis, comparison, and prediction of drought trends spanning the period from 1993 to 2023 in the study area. Employing a comprehensive methodology, utilization of the Modified Mann–Kendall test to analyze drought trends, while assessing drought severity through the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) has been done. Further research entails assessing the link between SPI and SPEI utilizing the Pearson correlation coefficient and simple linear regression techniques. Additionally, the Support Vector Machine (SVM) and Random Forest (RF) methods were used for predictive modelling feasibility. The findings helped to deepen our understanding of drought dynamics in the region, providing important insights for drought mitigation and adaptation efforts. This study emphasizes the importance of using a variety of statistical techniques and machine learning algorithms to thoroughly analyze, compare, and forecast drought patterns, thereby informing evidence-based decision-making for sustainable water resource management and agricultural planning in Chhattisgarh, India.

Abstract The contemporary research article is central to understanding coal structure evaluation and the morphological development impacting its utilization in different applications. Through Mineral Liberation Analysis (MLA) designs high content phyllosilicates minerals and swelling clay minerals were rationalized to provides a novel insight into enhanced coal beneficiation and the benefits of coal by-product re-utilization progressions that encourage safer environments and economic sustainability. This work commences with collection of five (5) different coal samples from the central district region in Botswana, sample characterization deploying Thermogravimetric coal analysis (TGA), x-ray fluorescence spectroscopy (XRF), x-ray diffraction (XRD), scanning electron microscopy (SEM) and the Hardgrove Grindability Index (HGI) test that was directed to quantification of the coal hardness and fracture toughness during milling. The cumulative objective was to understand the correlation that exists between the natural composition of the coal sample and their adaptation and application in various carbonaceous products. A solid connection was thus identified in the sulfur and phosphorus weight percentage inclusions in all the coal materials hence higher significance in sphalerite mineral phases (Zn, Fe) S critically increased the fracture toughness and hardness properties. Moreover, mineral amalgams intrinsic to the coal maceral such as aluminum oxides (Al2O3), silicate (SiO2), calcites (CaO), Iron oxide (Fe2O3), potassium feldspars (K − AlSi3O8), albite (Na − AlSi3O8), and anorthite (Ca − Al2Si2O8) compounds in alkali feldspars were detected in larger quantities. The coal industry has attracted much industrial attention to manufacturing foundations producing cement, ceramic tiles, paving bricks, and material synthesis and will continue to supply other economic sectors in the conceivable future. Graphical Abstract

Abstract Granites are widely distributed, phaneritic igneous rocks renowned for their high compressive strength and durability, making them a premier choice for dimension stone applications. This study aims to detect and map granitic complexes using geospatial data and spectral algorithms within the arid and semi-arid environment of northwestern Parwan Province, northeastern Afghanistan. Also, to establish an effective and optimized supervised classification approach specifically tailored for identifying granitic complexes in similar terrains. This study utilizes FCC imagery to highlight lithology and employs various machine learning algorithms, including ML, MD, SVM, and SAM, for mapping granitic complexes within the study area. Training and test data were collected from field observations, Google Earth imagery, and geological maps. Our analysis identified two primary granitic complexes within the study area, measuring approximately 19 km × 13 km2 and 7 km × 3 km2, respectively. Ground truth data validation yielded an accuracy of 75%, indicating a positive correlation between the predicted and observed distributions. This enhanced understanding of granite distribution can serve as a valuable guide for future exploration endeavors targeting metallic and non-metallic resources, including aluminum, iron, manganese, rare earth elements, tungsten, etc.

Abstract We propose a new reaction device for the microdiffusion analysis of CO2 in fluid samples from volcanic areas to improve the conventional analysis procedure, which requires a fixative and good handling skills. To accomplish this, a small resin reaction cell for the sample solution and acid (initiator for CO2 liberation) was devised and placed in a commercially available air-tight glass container with a Petri dish to form a microdiffusion analysis unit. The analysis was based on the principles of the conventional manual titration method that uses Ba(OH)2 as the CO2 absorbent. Using the new device, 99.5% recovery, with a relative standard deviation of 4.5% (n = 8), was achieved in a test analysis for 0.03 mmol of CO2 liberated from a Na2CO3 solution as a simulated sample. The analytical performance of the new device was almost comparable to that of conventional units under the experimental conditions of this study. Applying this new device for analyzing fluid samples from volcanic areas will contribute to enhancing the performance by reducing the possibility of CO2 contamination and by simplifying the process by eliminating the need for preparatory cleaning for fixative application. Graphical Abstract

Abstract This study aimed to investigate co-seismic stress and aftershock distribution along the Sumatra–Andaman subduction zone (SASZ). The fault parameters of six major earthquakes with an M ≥ 7 that occurred during 2010–2022 along the SASZ, were utilized to determine the Coulomb stress change using numerical modeling techniques calculated on the receiver faults with similar focal mechanisms of the mainshock, strike-slip, thrust, and normal faulting, respectively. The earthquake events were then classified to analyze the aftershocks of major earthquakes in the area. These aftershocks were mapped in order to determine the relationship between the aftershock distribution and the areas of increased or decreased stress. The relationship between the co-seismic stress and distribution of aftershocks in the SASZ was found to mainly depend on the focal mechanism of major earthquakes and the type of receiver fault used for calculation. After a major earthquake in the SASZ, there are two possible patterns that most aftershocks will be generated from in the areas of increased stress. First, a major earthquake is a type of thrust fault calculated on the receiver fault using the focal mechanism of the mainshock. Second, a major earthquake is a type of strike-slip fault calculated on the receiver fault with an optimum-oriented strike-slip fault. This relationship is likely to represent the specific pattern of the seismotectonic stress in the SASZ that can be used to evaluate the risk areas of aftershocks after a major earthquake has occurred. Furthermore, two earthquake events with large magnitudes were generated following the respective major earthquake in the SASZ that were located around the areas of increased stress, indicating that these two earthquake events were likely triggered in areas of increased stress following the respective major earthquake. Therefore, this study concluded that after a major earthquake occurrence in the SASZ, the areas of increased stress have a higher risk of generating both a large number of aftershocks and a new large-magnitude mainshock event. The investigation of co-seismic stress is very important to estimate areas of increased stress after a major earthquake, as this can be useful for monitoring both earthquake and tsunami hazards in the area.

Abstract Core LC42, retrieved from the Central Basin of the northwestern Ross Sea, contains three distinct sediment facies (IRD (ice-rafted debris)-poor bioturbated sandy mud, IRD-rich massive sandy mud, and laminated mud) that are interleaved with each other and deposited over the last 1 Ma. The biogenic components (biogenic opal, total organic carbon, and total nitrogen) of the laminated mud layers are consistently higher than the other two facies throughout the core. Based on the depositional succession of sediment facies and IRD-related depositional processes in the Antarctic continental margin, the laminated mud layers without IRD have been deposited during the glacial periods, but the enhanced paleoproductivity in terms of biogenic components during the mud deposition is unexpected. Backscattered electron imagery substantiates distinctly different componentry of the alternating light and dark laminae in the laminated mud. In particular, the light laminae contain scattered diatom fragments and eroded sand-sized lumps of fossil-bearing mud, whereas the dark laminae are clayey and diatomaceous. Both laminae thus are characterized by the high biogenic components, but they are interpreted to have been principally recycled from older deposits because diatom fragments are mostly reworked and old and their archives are poorly preserved. During the glacial periods, these laminated muds were deposited downward by milky plumes of meltwater discharged underneath the advancing glaciers that scoured the earlier-deposited and semi-consolidated diatom-rich sediments. Our study thus highlights that the recycling of biogenic particles should be precautious to avoid the fallacy of paleoclimatic interpretation in formulating climate-productivity models in the Antarctic continental margin.

Abstract High-velocity lower crust (HVLC) near the continent–ocean transition zone is significant for recording magmatic activity and early rifting history and is likely to be sourced from various types of magma supplies, including passive decompression melting, hot mantle plume, active small-scale mantle convection, and fertile source mantle. In the northern margin of the South China Sea (composed of the Dongsha Passive margin to the west and the SW Taiwan active margin to the east), a large amount of geophysical data, including refraction seismic data, enable us to prepare a map of the thickness distribution of the HVLC and estimate its volume. After revisiting published data, the volume of the HVLC in the northern margin of the South China Sea is found to be comparable but slightly less than that in continental large igneous provinces such as the Deccan Trap of west-central India or oceanic plateaus such as the Shatsky Rise in the northwest Pacific Ocean, probably indicating that they may have similar active source origins. Based on a more feature-based analysis (h–v p diagram; a scatter plot showing mean velocity of lower crust versus corresponding crustal thickness) to identify the source of the underplating material in a magma-involved margin, we tentatively suggest that the HVLC along the Dongsha passive margin showing no h–v p correlation is most likely dominated by small-scale mantle convection of the Peikang–Dongsha mantle convection cell, and the HVLC along the SW Taiwan active margin showing a negative h–v p correlation is more likely to be dominated by the pre-existing distal domain of the continental margin. We propose that rather than being dominated by a hot mantle plume, small-scale mantle convection may be more likely to be responsible for the opening of the South China Sea, and suggest that a more inclusive geodynamic model to reconcile geophysical and geochemical observations should be further investigated.

Abstract Lutao is an islet off the eastern coast of the main island of Taiwan and is composed of pyroclastic agglomerates, volcanic breccias, lava flows, and dykes. There have been no reports of SIMS zircon oxygen isotopic data from Lutao Island so far, which has significantly hampered further understanding of its magmatic processes, such as crystallization, evolution, and generation of magma. In this study, we use zircon U–Pb dating, Lu–Hf and O isotopic analysis to constrain the age, origin, and magmatic processes of the volcanic rocks from Lutao Island. Integration of our new U–Pb and Hf–O isotope data with available published data allows us to better assess the timing and magmatic processes of Lutao Island in the context of the northern Luzon arc system. This work is the first report of SIMS zircon oxygen isotopic data of volcanic rocks from Lutao island. This study shows that the volcanic rocks from Lutao Island were generated by mantle-derived magma associated with high-T° hydrothermal alteration by seawater-derived fluids.

Abstract Carbon Dioxide Removal is essential for achieving net zero emissions, as it is required to neutralize any residual CO2 emissions. The scientifically recognized definition of Carbon Dioxide Removal requires removed atmospheric CO2 to be stored “durably”; however, it remains unclear what is meant by durably, and interpretations have varied from decades to millennia. Using a reduced-complexity climate model, here we examined the effect of Carbon Dioxide Removal with varying CO2 storage durations. We found that storage duration substantially affects whether net zero emissions achieve the desired temperature outcomes. With a typical 100-year storage duration, net zero CO2 emissions with 6 GtCO2 per year residual emissions result in an additional warming of 1.1 °C by 2500 compared to permanent storage, thus putting the internationally agreed temperature limits at risk. Our findings suggest that a CO2 storage period of less than 1000 years is insufficient for neutralizing remaining fossil CO2 emissions under net zero emissions. These results reinforce the principle that credible neutralization claims using Carbon Dioxide Removal in a net zero framework require balancing emissions with removals of similar atmospheric residence time and storage reservoir, e.g., geological or biogenic.

Abstract Deep-sea coral frameworks are understudied in the Red Sea, where conditions in the deep are conspicuously warm and saline compared to other basins. Habitat suitability models can be used to predict the distribution pattern of species or assemblages where direct observation is difficult. Here we show how coral frameworks, built by species within the families Caryophylliidae and Dendrophylliidae, are distributed between water depths of 150 m and 700 m in the northern Red Sea and Gulf of Aqaba. To extrapolate the known (ground-truthed) positions of these deep frameworks, we use environmental and geomorphometric variables to inform well-performing maximum entropy models. Over 250 km2 of seafloor in our study area are identified as suitable for such frameworks, equivalent to at least 35% of the area of photic-zone coral reefs in the same region. We hence contend that deep-water coral frameworks are an important and underappreciated repository of Red Sea biodiversity.

Abstract Volcanic heating is predicted by theory to affect the velocity of nearby glaciers. However, conclusive studies on a large scale are lacking. Here, we conduct a global comparison of the velocities of glaciers near active volcanoes (i.e. within 5 km) and those located elsewhere ( > 5 km from an active volcano). Our findings show that, when considered over an annual scale (e.g. 2017-2018) and controlling for other factors, glaciers near volcanoes flow 46% faster than those located elsewhere (based on median values). This finding strongly suggests that volcanic heating impacts glacier velocity at a global scale, and supports the idea that glacier velocity monitoring could be a valuable indirect tool to help volcano monitoring and eruption prediction, particularly where volcanic heating (and therefore subglacial melt) intensifies months or years prior to eruptions.

Abstract Anthropogenic climate change is altering patterns of extreme weather events across the planet, with far-ranging consequences for biodiversity. Increases in the frequency, duration, and severity of droughts are anticipated to substantially impact natural ecosystems. Here, we predicted the extent to which 1221 terrestrial vertebrates in the contiguous United States will be increasingly exposed to annual (12-month) and prolonged (36-month) drought, under three global climate models and two representative concentration pathways. On average, a 377% increase in annual drought exposure and a 579% increase in prolonged drought exposure are anticipated for the study area by 2050–2080, compared to 1950–2005. Species in the southwestern USA could see the largest increases in drought exposure, while this area also has the highest vertebrate diversity and an abundance of drought-threatened species. Our results aid in identifying vertebrates and ecoregions anticipated to see large increases in drought exposure, which can inform conservation strategies aimed at mitigating vertebrate extinction risks.

Abstract The widespread retreat of Svalbard glaciers has been frequently interrupted by short-lived surge advances. In the case of marine-terminating glaciers this is often expressed in the remodelling of coastal zones. Here, we analyzed the coastal zone changes in front of the recently surging Recherchebreen. The glacier advanced ca 1200 m since 2018 and suddenly stopped in June 2020 followed by the rapid formation of a delta system in front of its subglacial meltwater outlet. The delta advanced by ca 450 m with probably the fastest progradation rate ever detected in the Arctic region (ca 7 m/day). The synchroneity of the final slow-down of the glacier with the delta building indicates that this event records the release of stored water and sediments from beneath the glacier and thus provides direct evidence of drainage reorganisation at the termination of a surge. Such behaviour is likely common among Svalbard surging glaciers, but it only rarely leaves any direct geomorphic evidence.

Abstract Achieving sustainable rural land systems, including farms and forestry, is essential to achieve the European Union’s goal of fair and healthy food systems while becoming climate-neutral and halting biodiversity loss. Here we quantitatively assess the environmental and socioeconomic sustainability of rural land systems in Europe using spatial hotspot analyses based on 15 environmental and 9 social sustainability indicators from the European Sustainable Development Goals and the Common Agricultural Policy. We find high subsidy support for under-performing sustainability areas and low sustainability performance in areas producing the most calories. However, we identified two brightspots with good environmental and socioeconomic performance (Nordics and Central Europe), and five dragspots hindering sustainability: the Balkans, the Lowlands, Northern Italy, Southern Italy and Malta, and Southern Spain. Redirecting support to reward social and environmental benefits from land use can help achieve sustainability goals.

Abstract Global warming has led to a notable increase in heatwaves globally and regionally. In spring 2022, South Asia witnessed an unprecedented heatwave with temperatures breaking historical records and exceeding 5° C from climatological mean at several locations in the northern Indian subcontinent. Here, using 3D tracking, this heatwave ranked the most severe in the past 64 years, characterized by its protracted duration and wide spatial extent. The excess atmospheric heat, represented by temperature anomalies, during the mega-heatwave triggered rapid snowmelt across the snow-covered areas in the region, leading to an average loss of 42% in snow cover and 57% in snow depth of the regional snowpack. This rapid melting resulted in the complete disappearance of low-level snowpack in the western Himalayas, Pir Panjal, and Afghanistan highlands, leading to the lowest snowpack observed in the last six decades. Moreover, during the heatwave, the amount of snowfall received was only 29% of the long-term average. This combination of excessive melting and reduced snowfall culminated in a severe regional snow drought in spring 2022. The heatwave genesis lay a persistent high-pressure system over Northwest South Asia, reinforced by a quasi-stationary Rossby wave packet over Europe during the initial spell. Continuous heat from high-pressure ridges associated with circumglobal Rossby waves combined with the physical barrier of the Himalayas, lent staying power to this system during the second phase.

Abstract Slow-slip events at global subduction zones relieve tectonic stress over days to years. Through slow-slip cycles, high fluid pressures observed at the top of subducting plates are thought to fluctuate, potentially due to the valving action of an impermeable layer near the plate interface. We model teleseismic scattering data at the Manawatu deep slow-slip patch at the Hikurangi margin in New Zealand and find high seismic P-to-S wave velocity ratios, V P /V S , in the upper ~5 km of the subducting Pacific Plate, reflecting sustained elevated fluid pressures that decrease during slow-slip and increase during inter-slow-slip periods. Within a ~ 3 km thick lower crustal layer of the overriding Australian Plate, decreasing V P /V S during inter-slow-slip periods reflects permeability reduction due to mineral precipitation. Increasing V P /V S during slow-slip reflects increasing permeability and crack density, facilitating upward fluid transfer through this layer. Our results suggest it acts as a valve to relieve high fluid pressures in the subducting slab.

Abstract Tropical cyclones have a big impact on flood risk, and understanding how their activity interacts with population exposure under climate change is critical. Here we investigate spatiotemporal changes in flood risk using numerical models together with historical observations and future projections of tropical cyclone tracks. We find that tropical cyclone-related flood risk shifts from the Mekong Delta to the eastern lower Mekong Basin, driven by the interaction between tropical cyclones and population exposure. Historically, extreme precipitation from tropical cyclones increased flood risk in about 14% and decreased in 7% of the basin. Future tropical cyclones may increase flood risk in about 7% and reduce in nearly 18% of the basin. Moreover, population exposure growth has historically increased flood risk in 3% of the basin and is projected to result in a 1% increase. These findings highlight the complex interactions of tropical cyclone hazards and socioeconomic factors influencing flood risk.

Abstract The response of European precipitation variability to climate change is still poorly understood. Here we present a high-resolution speleothem record of Eastern Central European (ECE) autumn/winter precipitation to study decadal to centennial hydroclimatic variations in the European-Atlantic sector since the Last Glacial Maximum. The Cloşani Cave δ18O record shows that the reorganization of the North Atlantic jet following the demise of the Northern Hemispheric ice sheets lasted until c. 6000 to 5000 years before present. Trace element-derived semi-quantitative autumn/winter precipitation amount reveals that the late Glacial and the early to mid-Holocene experienced about 20–30% higher precipitation than present. During the deglaciation, we detect an increased decadal to centennial precipitation variability decoupled from millennial-scale North Atlantic temperature changes. The findings suggest that dynamic (rather than thermodynamic) processes determine regional precipitation variability and the probability of extreme precipitation events in ECE, highlighting the importance of understanding such dynamics for future predictions.

Abstract The alignment of clay minerals in sediments is of high importance for their mechanical and physical properties. The development of this alignment starts with the deposition of clay, its strength is measured by the crystallographic preferred orientation. So far, the early stages of sedimentation have been restricted to post-mortem observations. Here we present particle settling experiments in four dimensions (time and orientation, as a function of overburden and composition) observed in situ using synchrotron diffraction, in which kaolinite and kaolinite-illite mixtures were sedimented in water columns. The alignment strength in freshly settled sediments increases with overburden, but is higher in deionized water than in seawater. Alignment strength increases within the first few millimetres of overburden and stagnates afterwards. With illite added, the resulting alignment strength is substantially decreased. Our results demonstrate that electrostatic interactions between particles are overcome by gravitational forces already within the upper millimetres of sediment.

Abstract The conversion of tropical forests in the Amazon region for agriculture and other land uses is associated with health risks linked, for example, to air and water pollution from forest fires and agrochemical use. Several conservation policies introduced in the 2000s aimed at reducing deforestation in the Brazilian Amazon. Here we exploit variations in the regional targeting of these policies to measure human health externalities of conservation policy enforcement using a double-difference approach at close distance to the Amazon biome border. We find that the change in deforestation pressure reduces forest fire incidence. As a consequence, fine particulate matter concentrations in the air—a main vector for adverse health effects of fire smoke—also decrease. This leads to a reduction in the hospitalization and death prevalence rate due to respiratory health problems and other health benefits for the local population.

Abstract Ecological disturbance can affect carbon storage and stability and is a key consideration for managing lands to preserve or increase ecosystem carbon to ameliorate the global greenhouse gas problem. Dryland soils are massive carbon reservoirs that are increasingly impacted by species invasions and altered fire regimes, including the exotic-grass-fire cycle in the extensive sagebrush steppe of North America. Direct measurement of total carbon in 1174 samples from landscapes of this region that differed in invasion and wildfire history revealed that their impacts depleted soil carbon by 42–49%, primarily in deep horizons, which could amount to 17.1–20.0 Tg carbon lost across the ~400,000 ha affected annually. Disturbance effects on soil carbon stocks were not synergistic, suggesting that soil carbon was lowered to a floor—i.e. a resistant base-level—beneath which further loss was unlikely. Restoration and maintenance of resilient dryland shrublands/rangelands could stabilize soil carbon at magnitudes relevant to the global carbon cycle.

Abstract Many phytoplankton produce methane, a potent greenhouse gas. However, little is known about the relationship between their methane production and photosynthesis, which drives carbon sequestration in the oceans. Here, by ruling out the possibility of classical methanogenesis, we show that the bloom-forming marine microalga Emiliania huxleyi released methane during photosynthesis (did not generate it in darkness) while grown under different light levels, the amount of methane released correlated positively with photosynthetic electron transfer and carbon fixation. Under growth-saturating light, E. huxleyi produces methane at a maximal rate of about 6.6 ×10−11 μg cell−1 d−1 or 3.9 μg g−1 particulate organic carbon d−1. The microalga released up to 7 moles methane while fixing about 105 moles of carbon dioxide. Considering the higher global warming potential of methane than that of carbon dioxide and complicated processes involved in methane air-sea fluxes, the warming potential of phytoplankton methane production should be broadly evaluated.

Abstract Northern forests are an important carbon sink, but our understanding of the driving factors is limited due to discrepancies between dynamic global vegetation models (DGVMs) and atmospheric inversions. We show that DGVMs simulate a 50% lower sink (1.1 ± 0.5 PgC yr−1 over 2001–2021) across North America, Europe, Russia, and China compared to atmospheric inversions (2.2 ± 0.6 PgC yr−1). We explain why DGVMs underestimate the carbon sink by considering how they represent disturbance processes, specifically the overestimation of fire emissions, and the lack of robust forest demography resulting in lower forest regrowth rates than observed. We reconcile net sink estimates by using alternative disturbance-related fluxes. We estimate carbon uptake through forest regrowth by combining satellite-derived forest age and biomass maps. We calculate a regrowth flux of 1.1 ± 0.1 PgC yr−1, and combine this with satellite-derived estimates of fire emissions (0.4 ± 0.1 PgC yr−1), land-use change emissions from bookkeeping models (0.9 ± 0.2 PgC yr−1), and the DGVM-estimated sink from CO2 fertilisation, nitrogen deposition, and climate change (2.2 ± 0.9 PgC yr−1). The resulting ‘bottom-up’ net flux of 2.1 ± 0.9 PgC yr−1 agrees with atmospheric inversions. The reconciliation holds at regional scales, increasing confidence in our results.

Abstract Aerosols from South Asia directly enhance glacier melt over the Tibetan Plateau. While the transboundary transport of aerosols from South Asia towards the Tibetan Plateau has been extensively investigated from a tropospheric perspective, less focus has been given to the stratospheric dimension. Here we examined the impact of the sudden stratospheric warming in January 2021 on aerosol transport from South Asia towards the Tibetan Plateau via numerical simulation. The results revealed that the aerosol transport from South Asia to the Tibetan Plateau reduced by 30%–40% following the January 2021 sudden stratospheric warming event. The eastward-propagating wave train stimulated by the stratospheric sudden warming induced an anticyclonic anomaly from the Persian Gulf to northern China, south of which easterly anomalies hindered the aerosol transport from South Asia to the Plateau. This study provides valuable insights for predicting air quality over the Tibetan Plateau.

Abstract The success of coral restoration for the critically endangered Acropora palmata is understudied. Here, we examined how habitat and coral microbiomes influenced survivorship in four genets of A. palmata outplanted in three reefs. A. palmata microbiomes were correlated to reef and habitat and minimally to coral genet. Carysfort Reef exhibited the lowest survivorship which correlated to lower current velocity and a higher relative abundance of Rhodobacterales in A. palmata. Higher survivorship was present at Pickles Reef which correlated to the highest current velocity, and at North Dry Rocks with the shallowest outplant depth. Habitat factors driven by time of year such as higher levels of nitrate, nitrite, and temperature also correlated with a relative increase in a putative pathogen, Alteromonadales, and a decrease in an uncharacterized core bacteria. We suggest outplanting at sites with high currents, lower depths, and at lower concentrations of nitrate/nitrite to increase A. palmata survivorship.

Abstract The subsurface oceans of Enceladus and Europa are thought to be some of the best candidate environments for finding life beyond Earth. Realistically, the first missions aimed at searching for life on these worlds will likely be restricted to the shallow subsurface. Here, we investigated whether indicators of life, or biosignatures, deposited near the surface could persist long enough to be detected, given that the extremely harsh conditions there would tend to degrade them. We exposed Bacillus subtilis spores to Ocean World surface conditions and used electron microscopy combined with spectroscopic approaches to assess the preservation potential of structural and morphological biosignatures derived from spores. Our results show that spore structure is highly resilient in the face of extreme conditions long after they have been inactivated, suggesting that methods targeting cell morphology would be valuable components in a suite of life detection strategies used in future missions to Ocean Worlds.