Socio-economic scenarios and resulting global warming levels structure the understanding of causal chains of greenhouse gas emissions, air pollution control, land-use changes, the response of the Earth system, climatic impact-drivers, exposure, vulnerability, adaptation responses, and climate-related risks. Following the French Academy of Sciences workshop on “The climate emergency, a turning point” (2024), this manuscript provides an overview of the concepts and methodologies underpinning the Sixth Assessment Report of the Intergovernmental panel on Climate Change (IPCC) regarding the development of scenarios and the assessment of risks from the perspective of the physical science basis of climate change, and selected recent updates and advances. It includes (i) a brief overview of the current state of the global and regional climate and impacts in France, (ii) an overview of future warming scenarios spanning socio-economic scenarios, (iii) constrained climate projections for global warming, and (iv) low-likelihood, high-impact outcomes which are relevant to inform robust decision-making and risk management.
Over the past thirty years, the silicon cycle at the scale of continental ecosystems has become an important topic within the scientific community. Since the 1990s, this research has been driven primarily by growing awareness of the need to quantify the impact of anthropogenic activities on the environment, as well as by advances in understanding the beneficial role of silicon in cultivated plants and its application in agricultural practices. This review highlights the major developments in the study of the silicon cycle at the soil-plant scale since the pioneering work of Bartoli, particularly his cycle model (Bartoli, F. Environ. Biogeochem. Ecol. Bull. 35 (1983), pp. 469–476). Phytoliths are now recognized as key players in the silicon cycle at both local and global scales. They represent a significant source of dissolved silicon (DSi), especially in highly weathered soils. Human activities such as deforestation, grazing, agriculture, and urban land use have been shown to disrupt the Si cycle. The concept of plant-available silicon indicator (PAS) has been developed and is now used alongside other routine soil parameters (e.g., pH and grain size) to identify the drivers of DSi. In the future, greater attention should be given to the determination and the dynamics of the available Si pools in plants, the quantification of the effects of biological factors other than plants, and the impact of atmospheric silicon inputs. The main factors influencing the terrestrial biogeochemical cycle of silicon should be integrated into models to predict the evolution of silicon in soils.
We examine the accumulation and provenance of non-ferrous metals in a shallow peat sequence (60 cm) collected in the Valley of Chassezac (Narcettes, Cevennes) in the French Massif Central (FMC), one of the oldest mining districts in Europe. The core is dated between the Modern period (<250 years old) and the 5th millennium BCE ( 14 C and pollens). Trace metal (Pb, As, Sb, Cu, Ni, Zn) enrichments generally increase from mid-core at 31 cm [70 CE–180 BCE] to the top, with maxima during the Modern period (0–18 cm, <250 yr). Statistical analyses (Principal Component Analysis and a source apportionment MixSIAR Bayesian model) applied to trace metals and stable Pb isotopes enable to discriminate the excess Pb imprint and its geographic provenance from Pb–Ag mining in France and surrounding countries within the first 31 cm. The most striking findings are the almost non-existent imprint from the numerous Spanish mines and the overwhelming French and Italian source imprints. Few Greek mines also contribute Pb enrichment, most particularly at depth, during the Roman period and late Iron Age. As expected from its proximity to the Narcettes core, the FMC (northern area and the mont Lozère) and mines from the Alps dominate the French contribution. The significant input from the mont Lozère extends its well-known medieval Ag–Pb exploitation into the Roman, and possibly, Gallic periods. Finally, a specific enrichment centered at 47–51 cm [3.2–4.1 ky BCE] is clearly discerned for Zn, Cu and Ni that may be associated with indigenous Cu smelting from nearby Cu mining districts in the Languedoc region (Cabrières and Roquemengarde). This finding would signify one of the oldest atmospheric metal contamination at a remote French site.
This paper synthesizes recent research conducted within the framework of the Human–Environment Observatory (OHM) Pyrenees Haut-Vicdessos, focusing on long-term environmental contamination in this Pyrenean mountain territory. Drawing on studies in biogeochemistry, paleoecology, and atmospheric sciences, it contrasts two persistent pollutants with distinct temporal trajectories: lead and atmospheric microplastics. Lead represents a legacy contaminant linked to centuries of mining and industrial activity, whereas microplastics, whose accumulation has sharply increased since the 1950s, exemplify an emerging and globally distributed form of pollution reaching even remote mountain environments. Together, these investigations illustrate how past and present human activities leave lasting chemical imprints in high-altitude ecosystems. They also open new questions about the persistence, mobility, and ecological consequences of emerging pollutants, underscoring the need for integrated monitoring and risk-assessment strategies in mountain environments.
Groundwater systems are components of the Critical Zone, in dynamic balance with the climate and human pressure. Water and heat fluxes control biogeochemical processes and regulate both resource potential and system vulnerability. Evaluating system responses to climate and land use changes requires an estimation of subsurface structure, flow dynamics, and the spatial distribution of recharge and discharge zones. Classical hydrological data, such as water levels and river discharge, are commonly coupled with unconventional methodologies, including heat tracing, electrical resistivity tomography, and surface wave analysis. Their coupling via time-lapse monitoring and inversion frameworks enables the characterization of thermal, electrical, and mechanical interactions, thus encouraging a transition from static structure description to transient representations of groundwater. We identify key challenges, including data limitations, model uncertainty propagation, and the integration of transient variables and parameters into inversion workflows. Petrophysical and geostatistical approaches help overcome these issues by coupling geophysical and groundwater models, quantifying spatio-temporal uncertainties, and addressing scale change. Finally, choices regarding experimental design, parameter reduction, dimensionality, model hypotheses, and inversion scale must be assessed to balance parsimony with model accuracy. These developments underscore the central role of hydrogeophysics in advancing Critical Zone science and sustainable groundwater management. Emphasizing transient processes is essential for capturing how subsurface systems evolve over time in response to environmental changes.
During an environmental survey performed in winter and spring 2022, living (Rose Bengal stained) benthic foraminiferal faunas were investigated at 13 stations sampled within the Cassidaigne Canyon (NW Mediterranean Sea) and surrounding area. These stations are located between 265–2300 m water depth. For many decades, industrial bauxite residues of red mud have been dumped into the canyon via a submarine pipe, causing physical disturbance and chemical contamination. In January 2016, solid waste underwater dispersal ceased and was replaced with the dumping of a low-density liquid effluent. Six years after the cessation of red mud dispersal, our observations at the 725 m-depth station closest to the Cassidaigne Canyon submarine outlet show a better ecological quality compared to the 2012 (during the red mud dumping) and 2016 (ten months after the cessation of dumping) sampling, suggesting a putative biotic recovery at the seafloor. That being said, this station still presents the highest abundance of opportunistic species, and a noticeably altered benthic diversity. At the other twelve stations, foraminiferal standing stocks and simple diversity decrease with decreasing food input to the seafloor and increasing water depth. There foraminiferal composition, with a minor contribution of opportunistic and stress-tolerant species, echoes (1) the overall meso-oligotrophic patterns of a relatively stable ecosystem, and (2) the putative trophic effect of phytodetritus exportation in spring 2022.
The Paris Basin, long regarded as a region of very low seismicity, shows new evidence of recent tectonic activity. Re-examination of the pedosedimentary sequence uncovered during the 1993 excavation of the Paleolithic site of Beauvais "La Justice" reveals a fault system cutting through deposits dating from the Upper Pleistocene (-.60 to 45 ka), as well as their underlying strata (Paleocene and Upper Cretaceous). These faults, with a total vertical offset up to 25 cm, were mapped across the excavation and interpreted as tectonic in origin, excluding periglacial, karstic, or anthropogenic causes. Their location and geometry suggest a link to deeper crustal structures, potentially associated with the Pays de Bray anticline and related fault. This discovery aligns with broader reassessments of intraplate seismic hazard in France, prompted by the 2019 M-.5 Le Teil earthquake which demonstrated that moderate events could produce surface ruptures. The BLJ reinterpretation challenges the level of our knowledge of the fault activity and of their contribution to seismic hazard in the Paris Basin, mirroring how Le Teil reshaped perception of seismic hazard in the Rh & ocirc;ne Valley. The Pays de Bray fold and fault-or a secondary structure-may have generated the observed deformations, raising questions about its potential for larger earthquakes. The study emphasizes the need for further investigations to refine hazard assessments. It also highlights the value of interdisciplinary collaboration, to uncover hidden tectonic activity and improve seismic hazard models in low-seismicity regions.
The Sahel has long been plagued by drought, which along with human pressure has caused ecosystem degradation, biodiversity loss, and increased poverty of local populations. Thus, in 2005 African heads of state set up a project, named the “Great Green Wall” (GGW), to restore Sahelian ecosystems. Establishment of the GGW led to the founding in 2009 of the “International Human-Environment observatory Téssékéré (OHMi Téssékéré)”, between France’s National Center for Scientific Research and Cheikh Anta Diop University (Dakar, Senegal), to assist decision-making by providing scientific information. The OHMi’s research is conducted in the Ferlo, northern Senegal. This paper summarizes knowledge of the region’s biodiversity and how the GGW may affect it. Semi-natural grazed parklands dominated by grasses with scattered trees occupy over 90% of the surface. Eighty-two woody plant species, representing 55 genera and 26 families, have been recorded. Forbs (non-graminoid herbs) are more diverse but account for a small proportion of vegetation cover. The study of arthropod biodiversity is just beginning. A first study showed that 427 insect morpho-species visit the flowers of a single common tree species, Balanites aegyptiaca . Vertebrate biodiversity includes seven species of amphibians, eleven species of reptiles and 217 bird species, among them palearctic migratory species (including 60 waterbirds) some of which are classified at high protection levels on the IUCN’s Red List. Four species of micromammals (in order of decreasing abundance, Gerbillus nigeriae , Arvicanthis niloticus , Taterillus pygargus and Mastomys erythroleucus ) occur in the area. Nine species of large wild mammals occur, of which eight are nocturnal.
Iron is essential for the proper functioning of the entire production chain of marine biomass and of the ocean's food web. However, its biogeochemical behavior often makes it a limiting factor in ocean functioning. On a geological timescale, the initially reactive-iron reservoir is most often stored as iron sulfides in the sedimentary record. This study focuses on episodes occurring during the earliest stages of diagenesis. It shows that there is a cycle of reversible transformations of iron states before the situation becomes fixed by the formation of iron sulfides, the most emblematic of which is pyrite. The material studied here is an alternation of diagenetic limestone beds and marly interbeds of Tithonian age, observed along the cliffs of the Boulonnais region (Strait of Dover, France), and known as the Assise de Croy Formation. The early, authigenic carbonates of the limestone beds trapped iron-bearing, authigenic minerals, notably magnetite. This made visible the iron cycle, which can be described as cryptic because it goes unnoticed if nothing reveals it. This "fossilization" of the early stages of iron distribution, through the precipitation of diagenetic limestone, allows for a more refined understanding of the carbon cycle, particularly in its shallow marine compartment: indeed, the cryptic iron cycle actively participates in the remineralization of fragile (labile) organic matter.
The Lake Chambon area, located between the Col de la Croix-Morand and Murol (Massif Central, France), consists of a Hercynian crystalline basement partially overlain by Cenozoic formations, largely composed of volcanic products related to the Mont-Dore stratovolcano. The presentday topography, sedimentation patterns, and drainage network are strongly controlled by a complex fault system. A detailed morphostructural analysis identified more than 500 lineaments from a high-resolution digital elevation model (DEM), which were digitized and analyzed in a GIS environment using QGIS. A directional classification combining expert-based interpretation with a semi-supervised machine-learning approach (k-means clustering) revealed seven major fault families, grouped into clusters consistent with a regional dextral shear regime. An interpretive tectonic model is proposed, consistent with the current stress field (sigma 1 trending between N160 degrees E and N170 degrees E). Faults of the F1 family are interpreted as dextral shear zones related to the South Armorican Shear Zone-Cholet-Poitiers Fault-Southern Border Fault of the Limagne graben system, associated with secondary Riedel-type structures. The influence of the sinistral Sillon Houiller Fault is expressed by the F6 '' family (N20 degrees E) and by the F2 ' family, whose orientation is comparable to that of the Tauves-Aigueperse fault system (N50 degrees E). The F4 family corresponds to extensional faults, locally reactivated within this broader strike-slip tectonic framework. The proposed neotectonic framework allows for the interpretation of several key geomorphological features. The Lake Chambon Basin may correspond to a transtensional pull-apart structure. In contrast, the slow-moving landslide at Chambon-sur-Lac, located between the transtensional zones of the Rochers de Pousseterre to the west and Lake Chambon to the east, appears to be controlled by the structural inheritance and kinematics of faults F4, F6 '' and F2 ', which locally accommodate oblique deformation within a transpressive regime. Finally, the study suggests that deep hydrothermal activity at Chambon-sur-Lac may be linked to regional seismicity associated with the F1 fault system.
This study evaluates the potential of machine learning approaches to forecast the daily volcano-tectonic seismicity and GNSS deformation data that are used to monitor the active Piton de la Fournaise volcano (La R & eacute;union Island, France). We tested six different methods to forecast the next five days of the geophysical signals: a naive baseline method, a linear regression model, and four different artificial neural network models including feed-forward, 1D convolutional, LSTM and Transformer architectures. All machine learning models performed better than the baseline. Auto-regressive Transformer models performed best for seismicity, while Linear models proved to be quite effective for GNSS data. Combining seismicity and GNSS datasets was not key to achieving better results. We also tested the GARCH model, a statistical econometric method. It shows no advantage in handling volatility and, like ML models, fails to anticipate sharp pre-eruptive accelerations. Results underscore the challenges of forecasting low-signal, non-cyclic volatile volcanic time series. The data we used may not contain all the necessary information for their own forecasting. Future developments may explore the addition of other data types, feature engineering, data generation, hybrid models and transfer learning. Those developments are important because machine learning models remain promising as complementary tools to existing volcano monitoring strategies.
In this study, we present and discuss changes in carbon storage in French forests from 1990 to 2022, derived from CITEPA statistics on forest carbon accounting. These statistics are primarily informed by National Forest Inventory (NFI) data collected from systematic samples of forest plots across Metropolitan France, as well as additional sources related to forest removals, soils or wood products. As NFI is designed to provide statistical estimations of forest growing stock, gains and losses only at the national or subnational levels but not to deliver detailed spatial outlooks on disturbances carbon losses from fires, droughts and insect attacks, we also outline a prospect for future improvements enabled by remote sensing and the development of multi-source inventories. At a national level, a continuing removal of CO2 from the atmosphere occurred from 1990 to 2022, as harvest and mortality-induced CO2 losses remained smaller than CO2 removals by forest growth and the increase in forest area (ca. 80 000 ha per year since 2005 but insignificant in terms of increased carbon stocks at present). The CO2 removal by forests was 49.3 MtCO2 & centerdot;yr-1 in 1990, increased to reach a peak of 74.1 MtCO2 & centerdot;yr-1 in 2008 and then quickly decreased down to 37.8 Mton CO2 & centerdot;yr-1 in 2022. The changes in CO2 removal by forests can be separated into three phases. From 1990 to 2013, the CO2 removal increased alongside the increasing growth of living trees. A spike in carbon loss was caused by the passage of the Lothar and Martin extra-tropical cyclones but forests recovered rapidly within a few years. In contrast, from 2013 to 2017, the CO2 removal by forests quickly decreased due to increasing CO2 losses from harvest and natural mortality and a trend of decreasing productivity (Hertzog L. R. et al., Sci. Total Environ. 967 (2025), article no. 178843), each process contributing almost equally. After 2017, the sink remained low and mortality rates stayed larger than during any of the previous years. The recent period is marked by climate shocks such as summer droughts and heatwaves in 2015, 2018, 2022, 2023. The full impacts of the droughts in 2022 and 2023 are not yet covered with full precision, as some of the sites measured by the national inventory before those droughts are still pending a second visit. Delayed tree mortality can also manifest years after a drought has occurred. At a regional level, contrasted trajectories were identified. Southern Mediterranean regions where forests have a low harvest rate have also experienced a lower increase in mortality and a sustained CO2 uptake. Despite high harvest intensities, the Landes plantations also show an increasing CO2 sink. In contrast, all northern regions and Corsica have seen a strong decline in their CO2 removal rates, except in the Ile-de-France region (larger Paris area), where the CO2 sink was constant during the last 30 years, possibly because many forests are used for recreation and are subjected to low harvest pressure. Two regions, the Hauts-de-France and Grand Est forests, stand out as becoming net emitters of CO2 to the atmosphere. Other regions where the CO2 sink declined and is now close to zero are Normandy, Corsica, and Bourgogne-Franche-Comt & eacute;. A detailed analysis was conducted to identify where trees are dying in France, the regions with increased mortality, and which species and tree sizes are most affected. We conclude with a perspective on how traditional sample-based statistical estimation of forest carbon changes, as implemented in classical NFI approaches, can be complemented by high-resolution satellite and LiDAR data, together with denser monitoring of mortality processes. Progress in remote sensing technologies supports both model-based approaches aimed at mapping the carbon budget and enhanced inventory techniques for accurate estimation at finer spatial scales. Given the limited continuity of some long-term forest flux estimates, we finally outline potential pathways to strengthen carbon sink quantification in the near future.
Humanity is confronted with unprecedented challenges related to climate change, water scarcity, and food security, as underscored by the United Nations Sustainable Development Goals (SDGs). Overpopulated megacities, such as S & atilde;o Paulo, are particularly susceptible to these issues, which are anticipated to have significant environmental and social consequences. Tackling these emerging challenges necessitates a holistic approach to comprehending the increasing human influence on physical, biological, and social environments. This paper emphasizes the Critical Zone Observatory (CZO) initiative in a crucial area of S & atilde;o Paulo, a megacity that has undergone various urban transformations over the years. The S & atilde;o Paulo CZO seed site aims to address vital questions concerning the anthropogenic impacts on groundwater, soil, and vegetation. We present environmental magnetism techniques and geochemical analyses carried out to enhance our understanding of the structure and dynamics of the critical zone. The findings reveal notable discrepancies between soil analyses obtained through geochemical and environmental magnetic methods. Magnetic parameters have pinpointed a significant interface in the saturated zone, revealing transformations in mineral phases and grain sizes of iron-bearing minerals. At greater depths, magnetic properties distinguished samples closer to the Tiet & ecirc; River, which is heavily affected by sewage, potentially indicating geochemical changes caused by interactions with polluted waters. Environmental magnetism offers insights into the transformations occurring within both biotic and abiotic processes. These dynamic processes are frequently influenced by anthropogenic factors (e.g., soil contamination) and climatic events (e.g., droughts and floods). Therefore, environmental magnetism serves as a valuable tool for monitoring and understanding the resilience of the critical zone.
The critical zone is a dynamic and heterogenous environment where a broad spectrum of processes take place ranging from hydrological, chemical and biochemical and interactions of rocks, fluids, soils and biota. The use of non-invasive geophysical tools, such as ground penetrating radar (GPR), to investigate the soil-plant continuum of agricultural crops within the critical zone has become increasingly popular. The continuum's complexity poses challenges, as the different components dynamically influence each other and the interactions and processes are not fully understood. Furthermore, establishing a direct link to geophysical information remains challenging. This study quantifies the impact of root distributions on GPR signals and soil water content (SWC) estimation. We investigated the influence of root volume fraction (RVF) on SWC calculation in a synthetic feasibility study before we performed numerical forward modeling using gprMax. Here, we analyzed GPR traces for different scenarios containing soil, roots and above-ground shoots. Thereby, we included two root distributions related to contrasting soil types based on field root counts. We observed that roots had a higher impact than above-ground shoot. Additionally, not considering roots in the calculation of SWC led to an SWC underestimation, depending on the soil permittivity and root volume fraction.
Juxtaposing incremental solutions can no longer respond to the climate emergency. This requires integrated approaches that take into account the interdependencies between actors and combine the levers of transformation-technological, behavioral, regulatory, and financial. The European Commission has created five Missions under Horizon Europe, reinforcing the coherence of objectives and means in support of the Green Deal. Notably, the "Smart and climate-neutral cities" and "Adaptation to climate change" Missions support cities, metropolitan areas, communities and regions that are aiming for decarbonization and climate resilience by 2030. In this paper, we discuss some structuring projects for these Missions, and other systemic innovation initiatives anchored in specific places, in particular Deep Demonstration programs led by Climate KIC in support of national and regional governments.
The Fengjiaping Landslide, located at the transitional zone between the western Qinling Mountains and the southwestern margin of the Loess Plateau in China, is a reactivated loess-mudstone interface landslide. Its complex evolution is influenced by geological, hydrological and climatic factors, as well as human activities. The critical zone regulates precipitation infiltration, which, in turn, controls soil moisture and groundwater dynamics. Although excessive water infiltration is recognized as the primary trigger, the landslide exhibits heterogeneous deformation, with recurrent events not always correlated with rainfall, making its reactivation mechanisms difficult to understand and predict. Potential sliding zones in moisture-induced landslides are typically characterized by high soil moisture and elevated water fluxes, manifesting as low electrical resistivity and enhanced streaming current densities. In this study, we applied an integrated geophysical approach, combining direct-current electrical resistivity tomography (ERT) and self-potential (SP) measurements, to infer subsurface water pathways and identify zones potentially contributing to slope instability. The joint interpretation of SP and ERT data suggests preferential flow channels and groundwater activity beneath scarps and cracks, highlighting their potential role as conduits for infiltration and slope weakening. Despite these insights, uncertainties remain due to limitations in data coverage, boundary effects, and simplified assumptions in the inversion framework. Future work should focus on continuous and time-lapse SP and ERT monitoring, complemented by methods such as induced polarization and borehole investigations, to better constrain subsurface hydrogeological properties and improve the understanding of the processes governing slope instability.
Obtaining accurate chronostratigraphic constraints on continental deposits is challenging, necessitating innovative dating approaches. Here, we investigate the feasibility of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) U–Pb dating of dinosaur eggshell fragments from the Late Cretaceous of Provence, France. Preliminary optical, Scanning Electron Microscopy (SEM), and cathodoluminescence (CL) analyses were critical for identifying zones of optimal preservation and mitigating potential diagenetic contamination. Results from two samples attributed to Megaloolithus mamillare and Cairanoolithus dughii yielded ages of 67.4 ± 4.4 Ma (2s, n = 60 ) and 69.5 ± 9.9 (2s, n = 50 ), respectively, broadly consistent with regional stratigraphic markers. Element mapping reveals significant spatial variation in U and Pb concentrations within individual eggshells, with zones of high contamination contrasting with well-preserved cores. The data highlight the crucial role of diagenesis and organic matter in influencing U–Pb system behavior, although it appears to be limited to early diagenesis. While LA-ICP-MS U–Pb dating of dinosaur eggshells presents substantial challenges, this study demonstrates its potential with careful sample selection and nuanced interpretation, paving the way for further refinement and broader application.
Geological data show that, early in its history, the Earth had a large-scale magnetic field with an amplitude comparable to the one of the present geomagnetic field. However, its origin remains enigmatic and various mechanisms have been proposed to explain the Earth's field over geological time scales. Here, we critically evaluate whether tidal forcing could explain the ancient geodynamo, by combining constraints from geophysical models of the Earth-Moon system and predictions from turbulence studies. Our analysis shows that lunar tidal forcing could have been sufficiently strong before-3.25 Gy to trigger turbulence within the Earth's core, and potentially to sustain dynamo action during that interval. Then, we propose new scaling laws for the magnetic field amplitude B. We expect the latter to scale as B proportional to /34/3, where /3 is the equatorial ellipticity of the liquid core, if the turbulence involves weak interactions of three-dimensional inertial waves. Alternatively, in the regime of strong tidal forcing, the expected scaling becomes B proportional to /3. When extrapolated to the Earth's core, it suggests that tidal forcing alone was too weak to possibly explain the ancient geomagnetic field. Therefore, our study indirectly favours another origin for the early Earth's dynamo on long time scales (e.g. exsolution of light elements atop the core, or thermal convection due to secular cooling).
The absolute entropy of seawater is defined as an improved version of the relationship defined by Millero in 1976 and 1983. The first improvements concern the complex non-linear dependence of entropy on pressure, temperature and salinity, with the use of the standard TEOS10 formulation based on a fit of the oceanic Gibbs function to more recent observations. On the other hand, more recent thermodynamic tables have been used to increase the accuracy of the Millero's salinity increment to this standard formulation, to deduce the absolute version of entropy with new values for the pure-water and sea-salts absolute reference entropies. The differences between the values of the seawater entropy calculated with the Millero and TEOS10 formulations (standard and absolute) are documented, before a more complete study shown in the second part of the paper of the absolute seawater entropy computed from observed vertical profiles and analysed surface datasets.
The aim of this second part of the article is to study the absolute definition of the seawater entropy described in Part I with several concrete cases. Observed vertical profiles and polar transects, as well as analysed surface data, show that very different temperatures and salinity values can organise to create new isentropic regions. This can only be revealed by the absolute formulation of the entropy of seawater (Arctic Ocean; Bay of Bengal; Mediterranean, Black, and Caspian Seas). Existing hypotheses to explain these results include the possible impact of turbulent processes that must be applied to the entropies of the atmosphere and oceans.
