Atmospheric and Oceanic Sciences

Abstract Peritoneal metastases (PM) occur in 10% of patients with colorectal cancer (CRC) and are linked to poor outcomes. Although dysregulated innate lymphoid cells (ILC) have been described in CRC, their function in CRC-PM remains unclear. Here, we analyze tumor samples from CRC and CRC-PM patients using single-cell RNA sequencing (11 patients), flow cytometry (8 patients) and differentiation assays (24 patients). Healthy colon, primary CRC and CRC-PM tumors are infiltrated by heterogeneous populations of ILC3, ILC2, ILC1, tissue resident (tr)NK cells and conventional (c)NK cells. Compared to healthy colons, primary CRC and CRC-PM tumors are depleted of ILC3 but enriched for ILC1, trNK cells and cNK cells. CRC and CRC-PM tumors harbor two immature ILC populations, early NK and naïve (n)ILC, with nILCs being transcriptionally skewed toward ILC1 and trNK cells. Indeed, co-culture of isolated nILCs with OP9-DL1 cells induces intratumoral nILC differentiation into ILC1/trNK-like cells. These findings help understand the immune pathogenesis of CRC and CRC-PM and provide insights for future ILC1 and NK cell-based therapies.

Abstract Photoinduced transition metal catalysis offers innovative strategies for fostering novel chemical reactions and improving established ones. In this work, we present a highly efficient, photoinduced Mn(II)-bipyridine catalyzed C–N, C-O and C-S coupling reaction between aryl halides—particularly less reactive aryl chlorides—and nucleophiles containing nitrogen, oxygen, and sulfur. This protocol does not need an external photocatalyst, as the single Mn(II)–bipyridine complex simultaneously serves as both the light-harvester and the metal catalyst. This method exhibits excellent substrate scope, covering eight different nitrogen sources for C-N coupling, as well as C-O coupling with alcohols, C-S coupling with thiophenols, encompassing more than 150 examples, with yields reaching up to 94%. Mechanistic studies suggest that this reaction may be initiated and sustained by the Mn(I) species through the photoinduced homolysis of the catalyst precursor bipyridine-Mn(II)(OAc) 2 , likely proceeding via a Mn(I)/Mn(III) catalytic cycle.

Chlorine atoms (·Cl) exhibit high reactivity and exert a substantial influence on the atmospheric oxidation capacity and chlorine cycle in the troposphere. The photolysis of molecular chlorine (Cl2) is a crucial source of ·Cl. However, the daytime peaks of Cl2 concentration cannot be entirely accounted for by the currently known pathways. Here we show that the photolytic oxidation of ammonium chloride (NH4Cl), a ubiquitous component of atmospheric aerosol, serves as an important daytime source of Cl2. Laboratory experiments demonstrate that oxygen, water vapour, and acidity are indispensable for Cl2 generation and release, and that Cl2 production is enhanced in the presence of black carbon aerosol. Field observation combined with model simulation demonstrates that the mechanism explains 12-55% of daytime Cl2 concentration. These results reveal a photoactivation pathway for chlorine production that depends only on chlorine salts and solar radiation, with significant implications in regions with abundant chloride salts. Sunlight triggers ammonium chloride in aerosols to produce Cl2 gas, explaining 12-55% of daytime levels. This chlorine source, boosted by black carbon, impacts atmospheric oxidation.

Effective host defense against pathogens requires coordinated behavioral and immune responses, yet the mechanisms that couple epithelial sensing to these systemic defenses remain poorly understood. Here, we identify a proton-mediated gut-to-neuron signaling pathway that orchestrates host defense in C. elegans. Intestinal pathogens stimulate mechanosensitive Ca²⁺ influx into intestinal epithelial cells (IECs) through the TRP channel GON-2, activating the Na⁺/H⁺ exchanger NHX-6 via the calmodulin CMD-1 to drive basolateral proton release. These protons activate cholinergic motor neurons through the acid-sensing ion channel ASIC-1, enhancing cholinergic transmission to promote both pathogen avoidance and intestinal innate immunity. Notably, mouse NHE1 and ASIC1a can functionally substitute for their nematode counterparts. Together, these findings demonstrate a role for proton signaling in gut-to-neuron communication, revealing a potentially conserved mechanism that links epithelial sensing to neuroimmune defense.

Energetic materials are central to propulsion and detonation technologies, yet their performance is often limited by poor control over energy release across multiple length and time scales. Integrating highly reactive composites with molecular explosives while maintaining structural precision remains challenging. Here we show a three dimensional printing strategy that enables programmable energetic composites by combining highly reactive metastable composite systems with a crystalline high explosive through acoustic-assisted assembly. Uniform coating and intimate interfacial contact produce dense architectures with enhanced thermal reactivity, accelerated pressurisation and increased energy output under confined conditions. Printed filamentary and core-shell structures further enable multistage and geometry-dependent energy release, including sustained combustion, secondary pressurisation and intense fireball formation. Laser-driven and combustion experiments reveal that the energy release characteristics can be systematically tuned by composition and architecture. This work establishes a general route to structure-performance control in energetic materials and highlights additive manufacturing as a powerful platform for designing next-generation reactive and explosive systems.

Accurate histopathological diagnosis typically relies on multiple chemical stains, a process that is labor-intensive, tissue-consuming, and environmentally taxing. While virtual staining offers a faster, tissue-conserving alternative, its clinical adoption is hindered by the requirement for perfectly aligned paired data, which is difficult to obtain due to tissue distortion during chemical processing. We present a robust virtual staining framework that mitigates spatial mismatches through a cascaded registration mechanism. By decoupling image generation from spatial alignment, our method enables high-fidelity staining even from imperfectly paired or misaligned datasets without altering existing model architectures. Our approach significantly outperforms state-of-the-art models across five datasets, showing a remarkable 23.8% improvement in image quality for highly misaligned samples. In blinded evaluations, experienced pathologists achieved 52% accuracy in distinguishing virtual from chemical stains, indicating that the two were indistinguishable. This framework simplifies data acquisition and provides a scalable pathway for integrating virtual staining into routine clinical workflows.

Lunar mare basalts are often rich in titanium, hosted predominantly within the mineral ilmenite (Fe2+Ti4+O3). Here, we examine ilmenite in a ~ 3.8 billion-year-old mare basalt (Apollo rock 75035) using high-resolution electron microscopy and electron energy loss spectroscopy. A key finding is that 75035 ilmenite is itself enriched in Ti, beyond the end member of the conventional solid solution series. Using energy loss near-edge spectroscopy, we determine that the excess Ti is trivalent, with Ti3+ accounting for 13% of the total Ti content. This discovery confirms the presence of trivalent Ti in lunar ilmenite, long hypothesized based on the Moon’s reducing environment. Accounting for the change in implied stoichiometry, a review of literature data suggests that Ti3+ may be present in ilmenite across a wide range of lunar samples. We extrapolate known relationships from the literature to connect Ti3+ to redox conditions, estimating the oxygen fugacity during crystallization of 75035 to be below the iron-wüstite buffer, ΔIW≤ − 1.6. Further quantifying the relationship between Ti valence state and oxygen fugacity would allow Ti3+-bearing ilmenite to serve as an oxybarometer able to access the reducing conditions found on many planetary bodies. Lunar rocks, not subject to complex crustal dynamics, reveal evolutionary aspects of the Earth-Moon system. The authors find that lunar ilmenite (age: 3.78 Ga) can host excess titanium in a trivalent state due to redox conditions not found on Earth.

• A three-dimensional clustering approach to identify drought events. • Coupling drought events with SIF enabled event-level assessment of vegetation photosynthetic sensitivity. • Vegetation photosynthesis exhibits heightened sensitivity under soil moisture deficits ≤ 30th percentile. Droughts exert profound impacts on the terrestrial carbon cycle, yet current understanding of vegetation carbon uptake remains largely constrained by the ways drought processes are characterized, particularly by the neglect of event-scale and process-level heterogeneity. In this study, we employed a three-dimensional clustering approach with daily soil moisture data (2000–2024) to identify 32 typical drought events across China, track their complete lifecycles, and link evolutionary characteristics to vegetation photosynthetic response thresholds. XGBoost model was further employed to disentangle the hierarchical influences of environmental drivers. Results show that summer constitutes the primary drought season nationwide, with events persisting significantly longer than those in other seasons. Droughts in the middle-lower Yangtze River Plain and Southwest China predominantly occurred in winter and spring, whereas those in the North China-Northeast Plain concentrated in early summer and frequently extended into late autumn. Regional dynamics varied markedly: North China-Northeast Plain droughts displayed longer migration pathways and faster propagation rates; Southwest China events were characterized by high intensity and prolonged stress, inflicting the greatest ecological impacts; Yangtze River Plain events were distinguished by extended duration. Vegetation photosynthetic responses differed by drought type: localized outbreak type droughts induced the highest sensitivity to soil moisture, yet displayed a declining interannual trend under low-threshold conditions (soil moisture percentile q ≤ 10). In contrast, under high-disturbance migratory type droughts, vegetation sensitivity weakened under highly correlated scenarios. Mechanistic analyses further revealed that topographic factors and vegetation functional traits amplified the effects of quasi-stationary type droughts on photosynthetic activity; net surface radiation and land-use type exerted greater influence during localized outbreak type droughts; whereas vegetation responses to high-disturbance migratory type droughts were predominantly governed by energy balance, with topographic modulation playing a relatively minor role.

• How geospatial foundation models (GFMs) perform in agriculture remains unclear. • We propose a workflow to benchmark Google’s AlphaEarth GFM for agriculture. • AlphaEarth is tested for yield prediction, tillage mapping, and cover crop mapping. • AlphaEarth rivals local models but lacks transferability, interpretability, and stability. • The benchmarking workflow and datasets can readily support future GFM evaluation. Geospatial foundation models (GFMs), pretrained on massive Earth observations (EO), have emerged as a promising approach to overcoming the limitations in existing featurization methods. Although most studies on GFMs have released the source codes and pre-trained weights, their deployment still demands extensive configuration, environment setup, inference EO preparation, and model fine-tuning. More recently, Google DeepMind has introduced AlphaEarth Foundation (AEF), a GFM pre-trained using multi-source EOs across continuous time. An annual and global embedding dataset is produced using AEF that is ready for analysis and modeling. The internal experiments show that AEF embeddings have outperformed operational models in 15 EO tasks without re-training. However, those experiments are mostly about land cover and land use classification. Applying AEF and other GFMs to agricultural monitoring requires an in-depth evaluation in critical agricultural downstream tasks. There is also a lack of comprehensive comparison between the AEF-based models and traditional remote sensing (RS)-based models under different scenarios, which could offer valuable guidance for researchers and practitioners. This study addresses some of these gaps by evaluating AEF embeddings in three agricultural downstream tasks in the U.S., including crop yield prediction, tillage mapping, and cover crop mapping. Datasets are compiled from both public and private sources to comprehensively evaluate AEF embeddings across tasks at different scales and locations, and RS-based models are trained as comparison models. AEF-based models generally exhibit strong performance on all tasks and are competitive with purpose-built RS-based models in yield prediction and county-level tillage mapping when trained on local data. However, we also find several limitations in current AEF embeddings, such as limited spatial transferability compared to RS-based models, low interpretability, and limited time sensitivity. These limitations suggest exercising caution when applying AEF embeddings in agriculture, where time sensitivity, generalizability, and interpretability is important. To our knowledge, this is the first study that systematically implements and evaluates embeddings from GFMs in agricultural downstream tasks across space, time, and spatial resolutions. The evaluation results and analyses can inform the design of future AEF versions and other GFMs and support their applications in agriculture and Earth science domains. Moreover, the proposed benchmarking workflow and datasets can be readily applied to evaluate future GFMs and facilitate their use in agricultural downstream applications.

• A radar coherence-based method enables individual-building damage mapping. • The method achieves 86% accuracy and outperforms existing rapid damage products. • An XGBoost model predicts building damage density under data-limited conditions. • Extends medium-resolution radar from area-based to building-level damage mapping. On 6 February 2023, two major earthquakes (Mw 7.8 and Mw 7.5) struck southern Türkiye, causing extensive building damage and substantial human casualties. Rapid post-earthquake response requires reliable information on damaged buildings at the individual-building level, yet most existing rapid damage products remain aggregated or area-based. This study presents an integrated framework that enables large-scale individual-building-level damage identification using medium-resolution Sentinel-1 SAR data and complements regional-scale damage prediction under data-limited conditions. In the first stage, a temporal coherence-based approach incorporating homogeneous pixel selection, non-local filtering, and multi-indicator fusion was developed to identify earthquake-damaged buildings across dense urban areas. The resulting Building Damage Proxy Map (BDPM) captures damage patterns at the scale of individual structures and achieves an average identification accuracy of 86%, outperforming existing rapid damage products by over 9%. Comparative analyses with independent SAR- and optical-based datasets demonstrate that the proposed method more reliably detects damaged buildings, including structures missed by optical imagery due to cloud cover, acquisition timing, or visually inconspicuous damage. In the second stage, an XGBoost-based model is applied to predict building damage density using seismic, topographic, geological, and building-related factors, providing regional-scale situational awareness when post-event observations are unavailable or delayed. Overall, this study advances the operational use of medium-resolution SAR data for building-level earthquake damage identification and offers a scale-aware framework for rapid damage assessment to support emergency response and recovery planning.

Water is a vital resource that requires long-term legal protection to ensure both ecological values and societal benefits. The European Union’s Water Framework Directive (2000/60/EC) is central to this aim, establishing binding requirements for good ecological and chemical status in all water bodies and legally binding environmental quality standards. Sweden has implemented the Directive into national law; however, its application has been characterized by legal ambiguities, particularly regarding the possibility of considering disproportionate costs in environmental measures. This study examines the scope and application of the disproportionate cost criterion within the context of environmental law and hydropower regulation in Sweden. A comparative overview of the criterion’s application in other EU/EEA countries is also provided. Based on a legal approach, the analysis focuses on how these rules affect hydropower, where the goal of renewable energy production often needs to be weighed against the requirement for ecological recovery. The study concludes that applying the disproportionate costs criterion requires transparency and legal certainty to ensure a fair balance between the social benefits of hydropower and the need for long-term protection of the aquatic environments. To avoid differences in how the criterion is applied in different EU Member States, harmonized guidelines are needed.

The development of renewable energy and the increasing demand for electricity underscore the importance of pumped storage for grid stability. Under low-flow pump operating conditions, pump-turbines frequently exhibit hump characteristics, causing severe hydraulic instability and strong pressure pulsations. This study investigates the formation of a hump using full-channel numerical simulations based on the Scale-Adaptive Simulation turbulence model. The numerical flow–head characteristics were validated against the available experimental H–Q data, while the pressure pulsation results were used for qualitative mechanism analysis. The results reveal three major mechanisms: pre-swirl and spiral backflow in the draft tube, non-uniform runner inflow, and vortex flow-induced separation in the wicket gates. An analysis of entropy production reveals that vortex dissipation is responsible for as much as 71% of hydraulic losses in the hump region. In order to mitigate these effects, four stabilizing fins were installed inside the draft tube. The simulations indicate that the fins possess the capability to inhibit swirl and backflow, confine the vortices within the fin–runner interface, improve inflow uniformity and reduce overall hydraulic losses. As a result, the structural modification significantly attenuates the pressure pulsation amplitudes at key monitoring points and visibly shortens the recovery periods. The region of the hump and positive slope of the performance curve are considerably reduced while the head near the region of the hump is increased. Although the intrinsic hump characteristic is still present, the fin-based flow-control strategy can effectively improve the performance and stability of the pump-turbine, which can guide the design and optimization of high-efficiency pumped-storage plants.

Transboundary river basins face water stress exacerbated by data scarcity and political instability, and most allocation models require ideal conditions that ordinarily do not exist. This study operationalizes Water Diplomacy Theory (WDT) for data-scarce, conflict-prone basins through quantifiable allocation rules—a critical gap as 310 transboundary basins worldwide face similar challenges. We address: (1) How can a four-stage allocation framework reduce basin-wide water stress under varying Institutional Capacity (IC), Data Transparency (DT), and Stakeholder Inclusion (SI)? (2) What treaty provisions achieve bindingness under upstream-downstream power asymmetries? (3) How does this framework advance beyond existing models in equity, efficiency, and adaptive capacity? We synthesize Water Diplomacy Theory with Hydro-political Security Complex Theory to construct a novel four-stage framework: initial allocation with ecological floors, conditional reallocation triggers, interannual water banking, and satellite-verified compliance. Drawing on 14 treaty precedents and 30-year hydrological data for the Salween River, we embed these rules in an open-source water banking model. Results demonstrate that increasing IC from low to high reduces basin-wide water stress by 34% (±7%, 95% IC) under drought conditions. Stakeholder Inclusion decreases allocation conflicts by 52%. Water banking outperforms priority rules by 23% across climate scenarios. Cooperation becomes self-enforcing when IC exceeds 0.55. The novelty and contribution to existing literature our study provides are: (1) first operationalization of hybrid commons-to-treaty transition with 85.7% empirically grounded clauses; (2) evidence that binding cooperative treaty design is achievable in weak-state contexts through institutional design; and (3) a portable template for data-scarce conflict-affected basins.

The hydropower plant, together with its reservoir, makes it possible to modify the natural flow regime. These changes can affect sediment transport dynamics and cause morphological changes in the river. If the river is also used as a waterway, the operational scenario of the hydropower plant can have a significant impact on sediment deposition, thereby reducing its navigable depths and increasing the risk of vessel–riverbed collisions. In this study, a 2D hydrodynamic model of the Danube River downstream of the Gabčíkovo Hydropower Plant (GHP) in Slovakia was developed to evaluate the influence of operational scenarios on maintaining the required navigable depths and to determine the most suitable scenario in terms of fairway maintenance costs. The operational scenario of the GHP influences the amount of sediment deposited downstream of the plant. The volume of deposition in the critical ford was approximately 50% smaller under hydropeaking than under run-of-river operation. The increase in riverbed elevation during hydropeaking was 33% to 64% lower than under run-of-river operation. The study results indicate that this reach of the Danube can remain navigable for a longer period without intervention (dredging), thanks to sufficient navigable depth maintained by erosion caused by hydropeaking, compared to run-of-river operation.

Promoting irrigation efficiency is a central pillar of global water sustainability strategies but empirical evidence shows a counterintuitive outcome named the irrigation efficiency paradox or rebound effect. This occurs when on-farm water savings do not translate into basin-scale conservation and may even intensify water scarcity. This paper critically re-examines the rebound effect, moving beyond conventional hydrological and economic explanations toward an integrated socio-hydrological perspective. We argue that the paradox is not merely a technical accounting issue or a form of the Jevons Paradox, but a systemic problem arising from interactions among behavior, institutions, and political economy. The review traces the concept’s evolution and synthesizes global evidence on its main drivers and controversies. It critically evaluates dominant research paradigms, emphasizing the need for greater methodological pluralism. Significant gaps remain, particularly regarding behavioral economics, political economy, and social and environmental externalities. We conclude that overcoming the efficiency paradox requires a policy shift from technological fixes to transformative governance.

The integration of Geographic Information Systems (GISs) with hydrologic science has evolved over seven decades from manual catchment delineation and output visualization to AI-native spatial water intelligence, reshaping how the water cycle is observed, modeled, and managed. This review explores that evolution, from the progressively tightening coupling between GIS software and hydrologic models to an AI-assisted future in which the line between these two fields blurs and eventually dissolves completely. The evolution of GISs in hydrology is traced through four eras, stratified as: (1) the formalization of governing equations and digital terrain representations (1950–1985); (2) the initial GIS–model coupling era and the rise in watershed simulation (1985–2000); (3) open source and the start of the open data deluge (2000–2015); and (4) machine learning and cloud-native computing (2015–present). A four-level vision for the role of artificial intelligence in the next generation of spatial hydrology is then articulated, from AI-assisted GIS operation to spatially aware AI water intelligence that reasons directly over geospatial data without requiring a traditional GIS or simulation software as an intermediary. Broader limitations and challenges are also discussed.

The enhancement of startup and performance in a Tetradesmus obliquus-polyurethane sponge biofilm system was investigated via the regulation of the phytohormone Indole-3-acetic acid (IAA). IAA supplementation at 1 and 5 mg/L increased biofilm biomass and chlorophyll a content, with the maximum biofilm biomass reaching 48.2 mg/g, and improved nutrient removal performance under shock-loading conditions, particularly for total nitrogen (TN) and total phosphorus (TP). IAA treatment was associated with EPS remodeling, including an increase in the protein/polysaccharide ratio to 0.68 and a 16% enrichment in tryptophan-like protein components. These EPS-related changes coincided with a decrease in the absolute zeta potential to −2.49 mV, which may be relevant to enhanced initial biofilm development. The corresponding EPS-related changes were characterized by three-dimensional excitation–emission matrix (3D-EEM) and Fourier transform infrared (FTIR) analyses using representative concentrations. Furthermore, the IAA-treated biofilm showed improved resilience under low, medium, and high loading conditions, with the most favorable TN removal reaching 87% at 1 mg/L IAA. These results suggest that IAA supplementation at 1 and 5 mg/L can promote microalgal biofilm start-up and improve nutrient-removal resilience under the tested conditions, with 5 mg/L showing the strongest response in biofilm growth and structural characterization.

Ground subsidence and shaft lining deformation caused by compressed dewatered bottom aquifers in deep unconsolidated strata mining areas are critical engineering challenges, making the study of the seepage–soil deformation coupling mechanism during groundwater injection remediation vital. This study built a visual cylindrical model (1025 mm × 150 mm); formulated well-graded analogous materials based on the D20 principle to simulate sandy gravel layers; embedded FBG sensors at 200/400/600 mm depths, combined with a dial indicator on the model top; and conducted two water injection–dewatering cycles. Results indicate: water injection generates excess pore water pressure, placing the entire model in a tensile stress state with top rebound; post-injection vertical stress redistributes (tension above the injection point, compression below, and an interlaced transitional band), validating the necessity of full-section injection; during the second injection–dewatering cycle, tensile strain at the upper monitoring point reaches 597.77 με, while compressive strain at lower depths reaches −253.90 με, internal deformation stabilizes within 6.5–10.0 days, injection improves the in situ stress state by reducing effective stress, and the deformation of the field strata remains in a stabilization period, with the stabilization time decreasing as the depth of the strata increases. This study clarifies the temporal evolution and representative spatial variation in internal strain at monitored depths during injection, providing theoretical and design references for optimizing water injection schemes to mitigate coal mine shaft damage.

Arsenic (As) is a ubiquitous and highly toxic metalloid with well-established carcinogenicity. Its accumulation and secondary release from lake sediments pose potential risks to lake ecosystem integrity and human health. Meanwhile, the ongoing intensification of lake eutrophication at the global scale has altered the sources, composition, and environmental behavior of internally derived dissolved organic matter (DOM). These changes have profoundly influenced As mobilization and transformation at the sediment-water interface (SWI). To advance understanding of the regulatory roles and underlying mechanisms of algal dissolved organic matter (ADOM) and submerged macrophyte dissolved organic matter (SMDOM) in As biogeochemical cycling under lake ecosystem regime shifts, extensive findings from the international literature were synthesized. The characteristic properties and environmental behaviors of ADOM and SMDOM were systematically compared, and their distinct regulatory pathways in lacustrine systems were further summarized. Results indicate that ADOM is typically characterized by low molecular weight, weak aromaticity, and high bioavailability. It can enhance As dissolution and mobilization from sediments through direct complexation, competition for adsorption sites, and stimulation of microbial metabolism and Fe(III) reduction. In contrast, SMDOM exhibits higher molecular weight, greater aromaticity, and a higher degree of humification. It tends to form stable complexes with mineral phases. Under the influence of radial oxygen loss (ROL) from submerged macrophyte roots during the growth phase, its capacity to promote mineral reduction is relatively limited. This process favors stable As retention in sediments. The regulatory effects of ADOM and SMDOM on As behavior are strongly modulated by environmental factors such as pH, redox potential (Eh), temperature, and light conditions, as well as by microbial communities. ADOM is more sensitive to reducing environments and photochemical processes. SMDOM, in contrast, exerts more persistent control under oxidizing conditions and at mineral-water interfaces. In addition, ADOM more readily drives microbial community shifts toward assemblages with enhanced capacities for Fe(III) reduction and As reduction or methylation. SMDOM is less likely to trigger strongly reducing processes. Based on these mechanisms, the outbreak and decay phases in algal-dominated lakes often correspond to critical periods of enhanced As mobilization and elevated ecological risk. In submerged macrophyte-dominated lakes, the decay phase may represent an important window for sedimentary As release. Finally, a conceptual framework describing the differential regulation of As biogeochemical cycling by ADOM and SMDOM is proposed. This framework provides a theoretical basis for As risk identification, the determination of critical risk periods, and the development of management strategies across lakes with different trophic states.

The FAO Irrigation and Drainage Paper 56, which was first published in 1998, has been widely recognized as a comprehensive guidebook for estimating crop evapotranspiration and calculating crop water requirements under various conditions, supporting the efficient management of water resources in agriculture. Over the past twenty-eight years, science and technology have significantly evolved in agricultural productivity and water resource mobilization, use, and management, as well as in research advances, data availability and management, and modeling capabilities and uses. However, these improvements have come against a backdrop of increasingly pressing challenges, especially those posed by climate change and water scarcity. Thus, considering all recent advances in knowledge, an updated version (FAO56 Rev.1) of that guidebook was recently released. The current article summarizes and highlights the main features and innovations that the revision has incorporated.