Assessing changes in global fire regimes
Background The global human footprint has fundamentally altered wildfire regimes, creating serious consequences for human health, biodiversity, and climate. However, it remains difficult to project how long-term interactions among land use, management, and climate change will affect fire behavior, representing a key knowledge gap for sustainable management. We used expert assessment to combine opinions about past and future fire regimes from 99 wildfire researchers. We asked for quantitative and qualitative assessments of the frequency, type, and implications of fire regime change from the beginning of the Holocene through the year 2300. Results Respondents indicated some direct human influence on wildfire since at least ~ 12,000 years BP, though natural climate variability remained the dominant driver of fire regime change until around 5,000 years BP, for most study regions. Responses suggested a ten-fold increase in the frequency of fire regime change during the last 250 years compared with the rest of the Holocene, corresponding first with the intensification and extensification of land use and later with anthropogenic climate change. Looking to the future, fire regimes were predicted to intensify, with increases in frequency, severity, and size in all biomes except grassland ecosystems. Fire regimes showed different climate sensitivities across biomes, but the likelihood of fire regime change increased with higher warming scenarios for all biomes. Biodiversity, carbon storage, and other ecosystem services were predicted to decrease for most biomes under higher emission scenarios. We present recommendations for adaptation and mitigation under emerging fire regimes, while recognizing that management options are constrained under higher emission scenarios. Conclusion The influence of humans on wildfire regimes has increased over the last two centuries. The perspective gained from past fires should be considered in land and fire management strategies, but novel fire behavior is likely given the unprecedented human disruption of plant communities, climate, and other factors. Future fire regimes are likely to degrade key ecosystem services, unless climate change is aggressively mitigated. Expert assessment complements empirical data and modeling, providing a broader perspective of fire science to inform decision making and future research priorities.
(Fire Ecology. vol. 20, pp. 18, 10/04/2026)
BYU, UNIBE, LCE, CNRS, UFC, UBFC, MSHE, CNRS, UFC, UBFC, OCCR, UNIBE, IMBE, AU, AMU, CNRS, RHUL, PAN, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE, UdeM, UBB, UBC, UEF, UTAS, UNSW, ZRC SAZU, UQAT, UQAM, UMR ISEM, Cirad, EPHE, PSL, CNRS, UM, Unibas, PSI, Unipd, LEHNA P3E, LEHNA, UCBL, ENTPE, CNRS, EPHE, PSL, LEHNA, UCBL, ENTPE, CNRS, CAM, LANL, ULISBOA, UMR Eco&Sols, Cirad, IRD, INRAE, Institut Agro, ANU, WITS, UMass Amherst, UMASS, NM-AIST, CREAF, CSIC, AWI, UIB, UTAD, UiB, BoM, UCHILE, IEB, UNIANDES, WSU, NC State, UNC, MPI-SHH, OMU, IIT Madras, UVic-Genome BC Proteomics Centre, UVIC, ECOBIO, UR, INEE-CNRS, CNRS, CNRS, UWO, CSIC, SLU, INIA, UAM, UON, MSU, NMC, UniGe, GEO3BCN–CSIC, CSIC, BEES, UNSW, QUT, ULISBOA, WWU, CNR, JCU, UNIA, IPHES-CERCA, URV, LIEC, INSU - CNRS, UL, CNRS, NIOZ, IAE NAS RA, NAS RA, UZH, UNSAAC, AU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The marine biodiversity impact of the Late Miocene Mediterranean salinity crisis
Massive salt accumulations, or salt giants, have formed in highly restricted marine basins throughout geological history, but their impact on biodiversity has been only patchily studied. The salt giant in the Mediterranean Sea formed as a result of the restriction of its gateway to the Atlantic during the Messinian Salinity Crisis (MSC) 5.97 to 5.33 million years ago. Here, we quantify the biodiversity changes associated with the MSC based on a compilation of the Mediterranean fossil record. We conclude that 86 endemic species of the 2006 pre-MSC marine species survived the crisis, and that the present eastward-decreasing richness gradient in the Mediterranean was established after the MSC.
(Science. vol. 385, n° 0036-8075, pp. 986-991, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Juvenile downstream migration patterns of an anadromous fish, allis shad ( Alosa alosa ), before and after the population collapse in the Gironde system, France
Diadromous fish have exhibited a dramatic decline since the end of the 20th century. The allis shad ( Alosa alosa ) population in the Gironde‐Garonne‐Dordogne (GGD) system, once considered as a reference in Europe, remains low despite a fishing ban in 2008. One hypothesis to explain this decline is that the downstream migration and growth dynamics of young stages have changed due to environmental modifications in the rivers and estuary. We retrospectively analysed juvenile growth and migration patterns using otoliths from adults caught in the GGD system 30 years apart during their spawning migration, in 1987 and 2016. We coupled otolith daily growth increments and laser ablation inductively‐coupled plasma mass spectrometry measurements of Sr:Ca, Ba:Ca, and Mn:Ca ratios along the longest growth axis from hatching to an age of 100 days (i.e., during the juvenile stage). A back‐calculation allowed us to estimate the size of juveniles at the entrance into the brackish estuary. Based on the geochemistry data, we distinguished four different zones that juveniles encountered during their downstream migration: freshwater, fluvial estuary, brackish estuary, and lower estuary. We identified three migration patterns during the first 100 days of their life: (a) Individuals that reached the lower estuary zone, (b) individuals that reached the brackish estuary zone, and (c) individuals that reached the fluvial estuary zone. On average, juveniles from the 1987 subsample stayed slightly longer in freshwater than juveniles from the 2016 subsample. In addition, juveniles from the 2016 subsample entered the brackish estuary at a smaller size. This result suggests that juveniles from the 2016 subsample might have encountered more difficult conditions during their downstream migration, which we attribute to a longer exposure to the turbid maximum zone. This assumption is supported by the microchemical analyses of the otoliths, which suggests based on wider Mn:Ca peaks that juveniles in 2010s experienced a longer period of physiological stress during their downstream migration than juveniles in 1980s. Finally, juveniles from the 2016 subsample took longer than 100 days to exit the lower estuary than we would have expected from previous studies. Adding a new marker (i.e., Ba:Ca) helped us refine the interpretation of the downstream migration for each individual.
(Journal of Fish Biology. vol. 104, n° 0022-1112, pp. 1054-1066, 10/04/2026)
UR EABX, INRAE, USC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SUNY Plattsburgh, SUNY, IPREM, UPPA, INC-CNRS, CNRS, ECOBIOP, UPPA, INRAE
An ensemble-based approach for pumping optimization in an island aquifer considering parameter, observation and climate uncertainty
In coastal zones, a major objective of groundwater management is often to determine sustainable pumping rates which avoid well salinization. Understanding how model and climate uncertainties affect optimal management solutions is essential for providing groundwater managers with information about salinization risk and is facilitated by the use of optimization under uncertainty (OUU) methods. However, guidelines are missing for the widespread implementation of OUU in real-world coastal aquifers and for the incorporation of climate uncertainty into OUU approaches. An ensemble-based OUU approach was developed considering parameter, observation and climate uncertainty and was implemented in a real-world island aquifer in the Magdalen Islands (Quebec, Canada). A sharp-interface seawater intrusion model was developed using MODFLOW-SWI2 and a prior parameter ensemble was generated containing multiple equally plausible realizations. Ensemble-based history matching was conducted using an iterative ensemble smoother which yielded a posterior parameter ensemble conveying both parameter and observation uncertainty. Sea level and recharge ensembles were generated for the year 2050 and were then used to generate a predictive parameter ensemble conveying parameter, observation and climate uncertainty. Multi-objective OUU was then conducted, aiming to both maximize pumping rates and minimize the probability of well salinization. As a result, the optimal trade-off between pumping and the probability of salinization was quantified considering parameter, historical observation and future climate uncertainty simultaneously. The multi-objective, ensemble-based OUU led to optimal pumping rates that were very different from a previous deterministic OUU and close to the current and projected water demand for risk-averse stances. Incorporating climate uncertainty into the OUU was also critical since it reduced the maximum allowable pumping rates for users with a risk-averse stance. The workflow used tools adapted to very high-dimensional, nonlinear models and optimization problems to facilitate its implementation in a wide range of real-world settings.
(Hydrology and Earth System Sciences. vol. 28, n° 1027-5606, pp. 303-319, 10/04/2026)
ULaval, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Antagonistic impacts of benthic bioturbator species: Interconnected effects on sedimentary properties, biogeochemical variables, and microbial dynamics
Macrofaunal species inhabiting intertidal mudflats and performing intense bioturbation are considered as ecosystem engineers, since they profoundly influence their physical, chemical, and biological environments. Nowadays, to complete our knowledge on the effect of bioturbation processes on the surrounding environment, interdisciplinary approach is essential to unravel their complex intertwined effects on intertidal mudflats. In this study, the effects of bioturbators on sediment properties, biogeochemical variables, and microbial dynamics (microphytobenthos, bacteria and archaea) were investigated. To this end, manipulation experiments were carried out in an intertidal mudflat of the Seine Estuary (France) by revamped the abundance of the two dominant bioturbators, Scrobicularia plana and Hediste diversicolor, in winter and late summer. Results showed that the presence of H. diversicolor in winter had a significant effect, with a significant increase in bed level accretion and microbial nitrate reduction rates. In contrast, the presence of S. plana showed no significant impact on sediment properties, most likely due to a reduced bioturbating activity at low temperature. In summer, both ecosystem engineers strongly influenced their surrounding environment but with opposite effects. The intense reworking of the sediment surface by S. plana limited microbial growth and enhanced erosion processes. Conversely, the presence of H. diversicolor favoured sediment accretion and enhanced microbial growth. Overall, this interdisciplinary study confirms the importance of these two ecosystem engineers in temperate estuarine mudflats by highlighting their simultaneous and intertwined effects on the sedimentary, physicochemical, and biological features. This confirms the importance of actively considering ecosystem engineers when restoring the natural habitats of tidal flats to cope with the different vulnerability risks related to global warming (sandification of estuarine sediments, disappearance of productive mudflats, sea level rise, vulnerability to storms and erosion).
(Journal of Experimental Marine Biology and Ecology. vol. 573, n° 0022-0981, pp. 152000-152000, 10/04/2026)
BOREA, UNICAEN, NU, MNHN, IRD, SU, CNRS, UA, METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ECOBIO, UR, INEE-CNRS, CNRS, CNRS, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité
Uncorrected satellite derived shoreline data assimilation in equilibrium modelling
(. vol. 32, pp. 821-828, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM
Foraminiferal test dissolution reveals severe sediment acidification in estuarine mudflats: new perspectives for present and historical assessment
Foraminiferal mudflat communities in the Auray estuary, located along the French Northwest Atlantic coast, were investigated in September 2020. Numerous living specimens of calcareous species showed marks of dissolution. The number of affected individuals, together with their dissolution degree, varied from one site to another. Moreover, pH profiles showed porewater acidification of the subsurface sediment at several stations. We propose two metrics quantifying the degree of dissolution: (i) the “Foraminiferal Test Dissolution” (FTD), based on binocular observations of the foraminiferal community, and (ii) the “Calcareous Test Preservation Ratio” (CTPR), surface ratio (0– 0.5 cm) of total living foraminiferal densities (0–1 cm). In stations showing sediment acidification, the O2-pH profiles show the typical biogeochemical signatures of cable bacteria activity (pH increase in the oxic zone followed by strong acidification in the suboxic zone). This suggests that bacterial activity could be responsible for the strong pH decrease leading to corrosive porewaters affecting calcareous tests, hence severe FTD in the first centimetre of sediment leading to high CTPR. Furthermore, observations of FTD in other estuaries on the French Atlantic coast indicate that the phenomenon has becomewidespread. Re-investigated foraminiferal tests sampled in 1995–1996 in the Auray estuary show no dissolution marks, suggesting that the dissolution process observed in 2020 appeared over the last thirty years. Therefore, the FTD and CTPR could be used as rapid tools to establish the occurrence of dissolution processes, pending geochemical confirmation. The FTD could also be used as sediment acidification proxy in historical records, where geochemical analyses are not possible.
(Comptes Rendus. Géoscience. vol. 356, n° 1631-0713, pp. 83-96, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPG-ANGERS, LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST, LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST, Nantes Univ
SOMLIT (Service d'Observation en Milieu Littoral) time series (French Research Infrastructure ILICO): long-term core parameter monitoring of French coasts
SOMLIT (Service d'Observation en Milieur Littoral) : a French Coastal Monitoring Network Coastal zones are where land, ocean and atmosphere interact. They are important for the exchange of matter and energy, and play a key role in (biogeo)chemical cycles at global scale. These environments are characterised by significant spatial and temporal variability of their physico-chemical and biological parameters due to local and seasonal meteorological drivers which are exacerbated by large-scale climate drivers (e.g. global warming, modification of the wind regime) and local-scale anthropogenic drivers (e.g. nutrient cycle changes linked to the use of fertilisers or the construction of large installations such as dams). These driving mechanisms are often interconnected. In the context of global warming (due to climate and human-induced changes), the identification and understanding of their impact on coastal marine and littoral ecosystems is essential. The scientific objective of SOMLIT is to 1) characterise the multi-decadal evolution of coastal marine and littoral ecosystems, and 2) determine the climatic and anthropogenic drivers. In order to meet this objective, a nationally coordinated multi-site monitoring system was set up in the mid-1990s. The observation strategy is the same for each of the 12 monitored ecosystems with fortnightly sampling and/or measurements, at high tide (for sites subject to tides): 1) in surface-water for a range of 15 parameters (temperature, salinity, dissolved oxygen, pH, nitrate, nitrite, ammonium, phosphate, silicate, suspended particulate matter, chlorophyll a, particulate organic carbon and nitrogen and stable isotopes of particulate organic carbon and nitrogen), 2) in surface-water for a range of 26 parameters of numbering and optical characteristics of pico- and nanoplankton), and 3) along the water column for temperature, salinity, fluorescence and PAR (vertical profiles of multi-parameter probes). SOMLIT’s activities are carried out under a quality assurance / quality control process based on the ISO 17025 standard. SOMLIT’s service provision objectives are to provide data and logistical support for research and other observation activities. SOMLIT has been officially accredited since 1996 as one of the CNRS (French National Centre for Scientific Research) National Observation Services (SNO). SOMLIT’s coordination is hosted by the Observatoire Aquitain des Sciences de l'Univers (University of Bordeaux / CNRS) and the service relies on strong partnerships with nine other institutions (University of Lille, University of the Littoral Opal Coast, University of Caen Normandy, Sorbonne University, University of Western Brittany, La Rochelle University, University of Montpellier, Aix Marseille University, National Museum of Natural History). SOMLIT is one of the nine networks that compose France’s Coastal Research Infrastructure (ILICO). SOMLIT has strong ties with ILICO’s other networks such as the SNOs MOOSE (Mediterranean Ocean Observing System on Environment), PHYTOBS (microphytoplankton monitoring) and COAST-HF (Coastal Ocean Observing System - High Frequency).
(SEANOE = Sea scientific open data publication, n° 2491-1836, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, OASU, UB, INSU - CNRS, ULR, CNRS, INRAE, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], ULCO, BOREA, UNICAEN, NU, MNHN, IRD, SU, CNRS, UA, CRESCO, MNHN, IFREMER, STAMAR, INSU - CNRS, SU, CNRS, AD2M, SU, CNRS, SBR, SU, CNRS, IUEM, IRD, INSU - CNRS, UBO EPE, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS, LIENSs, INSU - CNRS, ULR, CNRS, LOMIC, INSU - CNRS, SU, CNRS, OOB, SU, CNRS, OSU OREME, INSU - CNRS, CNRS, INRAE, UM, UMR MARBEC, IRD, IFREMER, CNRS, UM, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, OSU PYTHEAS, IRD, AMU, INSU - CNRS, CNRS, INRAE, LOV, INSU - CNRS, SU, CNRS, IMEV, INSU - CNRS, SU, CNRS, UMS POREA, INSU - CNRS, CNRS, INRAE
Vegetation response in NW Mediterranean borderlands to the millennial-scale climate variability of the last glacial period
Deep-sea pollen records from the Western European margin show that during the Last Glacial period (115-27 ka), regional vegetation oscillated between steppe and open forest in response to the millennial scale climate variability, Dansgaard-Oeschger (D-O) cycles and Heinrich events (HE), and that the magnitude of the forest expansions during D-O warming events was modulated by orbital parameters. However, little is known about the vegetation response in the northwestern Mediterranean region. Here, we present a new well-chronologically constrained high-resolution marine pollen record from the Gulf of Lion documenting the NW Mediterranean vegetation response during Marine Isotope Stages (MIS) 4 and 3. The pollen record highlights the strongest forest expansions during D-O 17-16 and D-O 8 in NW Mediterranean borderlands, likely driven by minima in precession. In this region, Heinrich Stadials (HS) 5 and 4 are marked by steppe landscapes while temperate forest surprisingly characterized HS 6. We hypothesize that the combination of minima in precession and local atmospheric and marine processes allows the development of the temperate forest in NW Mediterranean while the expansion of open environments occurred in other areas of Western Europe. In addition, our results support the hypothesis of Picea survival in NW Mediterranean during MIS 4 to 3.
(Quaternary Science Reviews. vol. 334, n° 0277-3791, 10/04/2026)
UB, UBM, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LCE, CNRS, UFC, UBFC, LMJL, CNRS, Nantes univ - UFR ST, Nantes Univ
Caractérisation in situ du comportement spectral des vagues en zone de surf
(10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LIENSs, INSU - CNRS, ULR, CNRS