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 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 present-day 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 ( σ 1 trending between N160°E and N170°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°E) and by the F2′ family, whose orientation is comparable to that of the Tauves–Aigueperse fault system (N50°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.

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 Croï 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 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.

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 ∝ β 4 / 3 , where β 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 ∝ β . 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).

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 CO 2 from the atmosphere occurred from 1990 to 2022, as harvest and mortality-induced CO 2 losses remained smaller than CO 2 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 CO 2 removal by forests was 49.3 MtCO 2 ·yr −1 in 1990, increased to reach a peak of 74.1 MtCO 2 ·yr −1 in 2008 and then quickly decreased down to 37.8 Mton CO 2 ·yr −1 in 2022. The changes in CO 2 removal by forests can be separated into three phases. From 1990 to 2013, the CO 2 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 CO 2 removal by forests quickly decreased due to increasing CO 2 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 CO 2 uptake. Despite high harvest intensities, the Landes plantations also show an increasing CO 2 sink. In contrast, all northern regions and Corsica have seen a strong decline in their CO 2 removal rates, except in the Ile-de-France region (larger Paris area), where the CO 2 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 CO 2 to the atmosphere. Other regions where the CO 2 sink declined and is now close to zero are Normandy, Corsica, and Bourgogne-Franche-Comté. 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.

The Francevillian Basin of Gabon (2.1 Ga) hosts one of the earliest known macroscopic organisms preserved within the fossiliferous FB2b subunit. Understanding the depositional conditions of this interval is critical for reconstructing the paleoenvironmental context of early complex life. In this study, multiple geochemical proxies (S/TOC, B/Ga, Sr/Ba, and Y/Ho ratios) are applied to evaluate paleosalinity across key stratigraphic units of the basin. Results indicate pronounced values variability. The FB2b interval is characterized by consistently low salinity, reflecting a freshwater-influenced depositional setting, while the FC and FB1c units show more marine-like signatures, in agreement with evidence of hydrothermal inputs. The FB2a and FB1b subunits display intermediate values, pointing to fluctuating freshwater–brackish conditions. These paleosalinity trends are consistent with previously recognized sea-level fluctuations, facies, and oxygenation patterns in the basin. The findings highlight the heterogeneity of hydrological conditions in the Paleoproterozoic Francevillian Basin and identify FB2b as a unique freshwater influenced setting that may have favored the development and preservation of early macroscopic life.

Available archives of past environments and climates in Senegal are relatively limited in number and concentrated in “Niayes” coastal area. The review of available data for the 6 ka–2 ka period presented here provides a major contribution, revealing that the end of AHP occurred in two successive stages. A first dry event was dated at 4.5 ka. However, its impact was considerably attenuated in this region due to specific conditions on the Atlantic coast, compared to other areas of the Sahel. Depending on the site, gallery forests were either minimally affected or, conversely, replaced by wooded grasslands. After a brief return to humid conditions, the Niayes region experienced dessication at 2.5 ka, with the drying up of water bodies and dramatic disruption of the gallery forests.