Abstract. The Great Oxidation Event (GOE) was a 200 Myr transition circa 2.4 billion years ago that converted the Earth's anoxic atmosphere to one where molecular oxygen (O2) was abundant (volume mixing ratio >10-4). This significant rise in O2 is thought to have substantially throttled hydrogen (H) escape and the associated water (H2O) loss. Atmospheric estimations from the GOE onward place O2 concentrations ranging between 0.1 % to 150 % PAL, where PAL is the present atmospheric level of 21 % by volume. In this study we use WACCM6, a three-dimensional Earth System Model to simulate Earth's atmosphere and predict the diffusion-limited escape rate of hydrogen due to varying O2 post-GOE. We find that O2 indirectly acts as a control valve on the amount of hydrogen atoms reaching the homopause in the simulations: less O2 leads to decreased O3 densities that reduce local tropical tropopause temperatures by up to 17 K, which increases H2O freeze-drying and thus reduces the primary source of hydrogen in the considered scenarios. The maximum differences between all simulations in the total H mixing ratio at the homopause and the associated diffusion-limited escape rates are a factor of 3.2 and 4.7, respectively. The prescribed CH4 mixing ratio (0.8 ppmv) sets a minimum diffusion escape rate of ≈2×1010 mol H yr−1, effectively a negligible rate when compared to pre-GOE estimates (∼1012–1013 mol H yr−1). Because the changes in our predicted escape rates are comparatively minor, our numerical predictions support geological evidence that the majority of Earth's hydrogen escape occurred prior to the GOE. Our work demonstrates that estimations of how the tropical tropopause layer and the associated hydrogen escape rate evolved through Earth's history requires 3D chemistry-climate models which include a global treatment of water vapour microphysics.

Shifting carbonate burial between oceanic and continental crust across Earth history

Paul Tapponnier, deciphering the Earth's crust deformation history in the rocks and landscapes

Understanding strain rates in naturally deformed rocks is crucial for reconstructing the tectonic history of orogenic belts. This study focuses on the Chahzar Thrust Zone, located within the Sanandaj-Sirjan metamorphic zone of southwestern Iran, an ideal setting for investigating deformation dynamics through microstructural analysis. We employ fractal analysis of quartz grain boundaries to estimate strain rates and assess deformation conditions. Although quartz microstructures such as bulging (250-400°C), subgrain rotation (400-500°C), and grain boundary migration (500-750°C) have been historically linked to specific temperature ranges, recent studies emphasize that these features are also strongly influenced by strain rate, fluid content, and other variables (Law, 2014). In this context, we apply the box-counting method to quantify the fractal dimension (D) of recrystallized quartz grains, using it as a semi-quantitative proxy for combined deformation conditions. Our results yield estimated strain rates ranging from 10⁻1⁰.⁹ s⁻1 to 10⁻⁶.⁸ s⁻1, which are notably higher than previously reported typical natural strain rates (10⁻12-10⁻15s⁻1). These findings suggest a deformation regime with episodic or localized strain intensification, contributing to a better understanding of strain accommodation in mid-crustal rocks and offering insights into tectonic processes in similar orogenic systems worldwide.

The Piacenzian (-3.6 to -2.58 Ma) represents one of the last major phases of global warming in recent Earth history, preceding the onset of Pleistocene glacial-interglacial cycles. Under conditions of global mean temperatures 2-3 °C higher than present, atmospheric CO₂ concentrations comparable to modern values, and elevated sea level, Central Europe experienced the expansion of extensive deciduous forests that dominated late Pliocene landscapes. This paper synthesises palaeobotanical and palaeoenvironmental evidence for Central European deciduous forests during the Piacenzian, focusing on environmental context, taxonomic composition, and ecological functioning. The analysis highlights the combined influence of warm climatic conditions, Atlantic oceanic circulation, and relatively stable precipitation regimes on the development of dense temperate forests. Orbital forcing during the late Pliocene nevertheless introduced climatic variability that affected regional biome distribution. Palaeobotanical records indicate a high diversity of Fagaceae dominated by Quercus and Fagus. White oaks acted as major structural elements, while beech shows marked morphological continuity between fossil and extant forms. A trait-based functional approach suggests that forest persistence relied on deciduousness, phenotypic plasticity, and, in oaks, interspecific hybridisation, primarily reflecting acclimation processes rather than major taxonomic reorganisation. The Piacenzian thus provides a valuable reference for assessing functional responses and acclimation limits of temperate forests under sustained warming, while emphasising the need for caution in actualistic interpretations.

Cerium is among the most important elements for understanding the redox state of the ocean throughout the Earth's history. Deep-sea ferromanganese crust is expected to be a major sink of Cerium in the oxygenated ocean, where Cerium enrichment from seawater is conventionally explained by inorganic oxidation on the surface of Mn oxide. As microbial colonization was demonstrated at the crust surface by recent studies, Cerium accumulation might result from microbial activities. Here we show microbe-like structures mineralized with Fe-Mn oxides at the deep-sea ferromanganese crust surface. Coordinated nanoscale solid analyses revealed that the microbe-like structures are enriched with Cerium and organic matter. The organic matter is enriched with aromatic and carboxylic functional groups rather than amide groups that are characteristic of living cells. The occurrence of Cerium (III) in the surface pit indicates the local establishment of conditions, under which Cerium (III) stably accumulated in the microbe-like structures. This new process found in the deep-sea environment with limited supply of photosynthetic organics could be relevant to ferromanganese oxides formed on ancient Earth and Mars. This article is part of the theme issue 'Planetary Protection for sustainable space exploration'.

The Late Triassic-Early Jurassic fissures of the Bristol Channel area (southwest England and south Wales) are renowned for their diverse vertebrate faunas. These assemblages have yielded an array of predominantly small-bodied forms that are crucial to our understanding of the early evolution of several major tetrapod clades. Although their dating remains contentious, these deposits provide a valuable insight into biodiversity at a key time in Earth history, given that they span the end-Triassic mass extinction. One of these fissure-fill taxa, Terrestrisuchus gracilis, represents one of the most completely preserved early-branching crocodylomorphs. This species currently occurs exclusively in Late Triassic deposits within the Pant-y-Ffynnon Quarry, whereas only generically indeterminate crocodylomorph remains have been recorded from other fissures in the Bristol Channel area to date. Here we present a detailed anatomical description of a specimen previously assigned to Terrestrisuchus sp. (NHMUK PV R 10002), which comprises the semi-articulated partial postcranial skeleton of a crocodylomorph from the Late Triassic fissure deposits of Cromhall Quarry in the Bristol Channel area. We incorporated NHMUK PV R 10002 into a pre-existing data matrix comprising 39 other operational taxonomic units scored for 138 morphological characters. Phylogenetic analysis under Maximum Parsimony recovers NHMUK PV R 10002 as the sister taxon to Terrestrisuchus, clustering in all cases with the contemporaneous German species Saltoposuchus connectens to form the non-crocodyliform crocodylomorph clade Saltoposuchidae. Under equal and extended implied weights, the Early Jurassic South African species Litargosuchus leptorhynchus and the Late Triassic US species Hesperosuchus agilis, respectively, are additional saltoposuchids. Although NHMUK PV R 10002 exhibits a high degree of morphological similarity to Terrestrisuchus, key differences are evident in the morphology of the dorsal vertebrae, fore- and hindlimb long bones, proximal carpals, metacarpals, and calcaneum. We therefore designate NHMUK PV R 10002 as the holotype of Galahadosuchus jonesi n. gen. n. sp. Several anatomical features indicate that Galahadosuchus was a highly gracile, cursorial terrestrial quadruped with an erect stance, including: elongate proximal carpals; long, slender, and tightly bunched metacarpals; development of a distinct, medially directed femoral head; and a classical crurotarsal ankle joint configuration. A similar stance is also reconstructed for Terrestrisuchus; however, some of the anatomical differences between these two taxa, including the relative proportions and morphology of limb and carpal bones, might correspond to differences in locomotory function, potentially reflecting varying specializations within early-branching crocodylomorphs.

The deposition of the sandstone sedimentary succession of the Beacon Supergroup lasted more than 200 Myr (Devonian to Early Jurassic) in Victoria Land and nearby territories in the so‐called Transantarctic Basin, recording crucial events in the history of the Earth. Sedimentation is synchronous with the convergence between the paleo‐Pacific plate and Gondwana, to form the large Gondwanide orogenic system. The composition of the Beacon Supergroup sandstones was found to be correlated with major tectonic processes in response to subduction dynamics, which ultimately conditioned the source‐to‐sink system and provenance imprints. Petrographic variability in sandstone composition is tracked through space and time by a quantitative analysis of all available published data and new updated ones, from the Transantarctic Mountains and Tasmania. The variability of grain composition detected by quantitative sandstone petrography reveals that the Victoria Land sector transitioned from an intracratonic basin in back‐bulge position to a foredeep basin setting.

Polyphosphate (polyP), a condensed linear form of orthophosphate residues, is functionally versatile phosphorus (P) polymer that has persisted since prebiotic Earth. Long treated as a cellular biochemical curiosity, it remains systematically overlooked in global P budgets and Earth system models. In this review, we compile the first global-scale synthesis of environmental occurrence, biological regulation, and ecosystem functions of polyP across terrestrial, freshwater, marine, and engineered systems. Integrating 568 environmental observations and over 3000 microbial genomes, we unveil that polyP is a quantitatively significant and phylogenetically widespread component of global P cycling, often comprising 5-40% of total phosphorus in major ecosystems. We synthesize current understanding of how microbial taxa, including bacterial or archaeal polyP-accumulating organisms and arbuscular mycorrhizal fungi, mediate polyP turnover and interact with carbon/nitrogen cocycling under fluctuating redox, nutrient, and climatic conditions. Our quantitative assessment reveals that global polyP stocks in soils, sediments, and wastewater systems form a substantial, yet previously unaccounted, reservoir of recoverable and climate-sensitive P. The omission of polyP from existing models creates systematic blind spots in understanding P bioavailability, retention, cycling, and sustainability. Integrating polyP into the global P narrative is essential for advancing new frontiers in climate-smart biogeochemical forecasts, circular nutrient management, and long-term water-energy-food ecosystem security under global climate change.

The first billion years of Earth history witnessed the emergence of continental magmatism, oceans and life. Yet, the details of how continents formed remain unknown because of the absence of preserved rocks1-8. Two conflicting Hadean models predominate: early onset of subduction and plate tectonics2-4, compared with early stagnant-lidandplume processes with delayed (post-Hadean) plate tectonics5-7. Here we report trace-element ratios (including Nb-Sc-U-Yb) correlated with age and hafnium and oxygen isotope ratios for Hadean detrital zircons from the Jack Hills(JH), Western Australia, which record unprecedented insights into the timing and setting of early magmatism. More than 70% of Hadean JH detrital zircons have Sc/Yb > 0.1, and 47% have U/Nb > 20, fingerprints for continental-arc and subduction settings. The remainder are ocean-island-like with little evidence for ocean-ridge settings. Hadean JH zircons probably originated from distinct terranes with separate tectonic histories. Subduction-related magmatism in the Hadean, as documented by JH zircons, alternated with periods of magmatic quiescence. This contrasts with dominantly stagnant-lid-like signatures for most Barberton Hadean zircons. The diverse settings for Jack Hills and Barberton detrital zircons imply contemporaneous operation of different tectonic styles during the Hadean, as well as a broader diversity of early crustal origins than previously known.

Abstract The Dohat Faishakh sabkha in Qatar was among the first modern environments studied to understand low‐temperature dolomite formation in association with gypsum and other evaporites. Since the 1960s, research conducted in this sabkha has significantly influenced geological models that remain widely used today, helping in the interpretation of sedimentary sequences that dominated certain periods of Earth's history. Here, we present results of an investigation of the dolomite occurring in this sabkha using techniques more advanced than those available during the initial pioneering studies. By integrating our new results with previously published data, we establish an ‘identity card’ for this sabkha dolomite and the environment it forms. The dolomite exhibits a rhombohedral morphology, contains 50.8 mol% Mg, and has an ordering degree of 0.25 (poorly ordered). Isotopic values are approximately: δ 13 C = 5.0‰, δ 18 O = 4.1‰ and δ 26 Mg = −2.6‰ to −1.5‰ and Δ 47 = 0.611‰. Annual temperature data indicate an average of 32.2°C in the subsurface intervals with the highest dolomite content. The associated pore water has an Mg/Ca ratio of 156, a salinity roughly nine times that of sea water and a pH of 6.9. Sediment total organic carbon is ~2%. Microbial diversity in the dolomite‐bearing layers is dominated by Euryarchaeota—an extremophilic, opportunistic and metabolically versatile archaeal phylum. Together, these data provide a reference for identifying sabkha‐type dolomites in the geological record, calibrating paleoclimatic proxies and interpreting biomarker signals that may be recorded in ancient dolomites.

Phanerozoic marine bioevents: A review with applications to stratigraphy and earth history

Seawater circulation through oceanic crust acts as an essential sink for CO2 and affects the alkalinity budget of the ocean. Seafloor weathering and ridge flank hydrothermal activity contribute to modern carbon sequestration by taking up carbon at a rate < 0.5 Tmol y−1. In addition, these processes release < 1 Tmol y−1 alkalinity to the ocean. During warmer eras in Earth history, the carbon uptake rates were considerably higher. Estimates range between 2.1 and 3.4 Tmol y−1 during the Cretaceous and Jurassic. The more intense carbonation of the seafloor in the Mesozoic is due to higher temperatures and less pelagic sedimentation in the deep ocean. Accelerated rates of reaction between seawater and basalt and prolonged durations of exposure of igneous crust to seawater led to more intense basalt alteration and carbonate formation within the crust. The interactions between oceanic crust and seawater hence profoundly influence global carbon cycling on long time scales.

The articles in this Elements issue describe outstanding questions about the dynamics of Earth’s carbon cycle. Study of the carbon cycle is extraordinarily interdisciplinary, with experts using a wide variety of tools—observational, analytical, and numerical. Here we focus on the final category and discuss how numerical (or computational) models of Earth’s carbon cycle help investigate carbon cycle conundrums throughout Earth history and into the present day.

The preservation of organic carbon (OC) in marine sediments is a fundamental control on Earth’s long-term carbon cycle and climate. Globally, less than 2% of carbon fixed by primary producers is ultimately buried, yet specific environments and geological intervals exhibit markedly enhanced preservation. These variations reflect changes in organic matter composition, mineral associations, microbial activity, geochemical conditions, temperature, and sediment transport. Planetary-scale changes in climate, tectonics, continental configuration, biological evolution, and ocean circulation have repeatedly altered these controls, promoting enhanced OC burial during key periods of Earth history. OC preservation has thus acted as an important stabilizing feedback following major carbon-cycle perturbations. Here, we examine these mechanisms and their significance through time.

Abstract While most near-Earth asteroids (NEAs) are thought to originate from the main belt, recent discoveries have suggested the existence of a lunar-derived NEA population, such as the asteroids Kamo‘alewa and 2024 PT5. These objects may hold key clues to the dynamical evolution of NEAs and the recent impact history of the Earth–Moon system. However, the population, distribution, and dynamical characteristics of these lunar-origin asteroids (LOAs) remain poorly constrained. By combining the lunar ejecta production with N -body orbital simulations of the ejecta, we investigate their orbital evolution in the past millions of years and the current LOA population, revealing their significant potential for detection by future surveys. Specifically for the Vera C. Rubin Observatory’s upcoming Legacy Survey of Space and Time, we predict an average detection rate of about six LOAs (with D > 5 m) per year. Additionally, we find that the LOAs tend to approach from sunward and antisunward directions, with encounter velocities significantly lower than those of typical NEAs. These findings offer valuable insights in guiding targeted ground-based surveys and planetary defense efforts for LOAs in the future.

Abstract. Stable nitrogen isotope records preserved in marine sediments provide critical insights into Earth's climate history and biospheric evolution. Although numerous studies have documented nitrogen isotope (δ15N) records for various geological systems (Archean to Recent) and paleogeographic settings, the scientific community remains constrained by the absence of a standardized database to systematically investigate their spatiotemporal evolution. Here, we present the database of Deep-time Sediment Nitrogen Isotopes in Marine Systems (DSMS-NI), a comprehensive global compilation of δ15N data and associated geochemical parameters, spanning a vast collection of sediment samples dating from the Recent to the Archean. This database encompasses 70 854 δ15N records derived from 417 publications, systematically organized with 31 metadata fields categories (e.g., chronostratigraphic ages, coordinates, lithology, metamorphic grade, sedimentary facies, references) encompassing 1 999 226 metadata. This repository further incorporates 130 proxy data fields, including 281 215 geochemical data spanning total organic carbon (TOC), total nitrogen (TN), and organic carbon isotopes (δ13Corg), major and trace elements and iron species. These integrated parameters enable evaluation of sample fidelity and factors influencing δ15N signatures. The DSMS-NI database will facilitate research for key geological intervals such as the Permian/Triassic boundary and the Cretaceous oceanic anoxic events (OAEs). Researchers can leverage temporal and paleogeographic information, alongside geochemical data, to conduct spatiotemporal analyses, thereby uncovering changes in deep-time marine nitrogen cycles and paleoenvironmental conditions. The database is open-access via the Geobiology portal (https://geobiologydata.cug.edu.cn/, last access: 30 April 2025), allowing users to access data and submit new entries to ensure continuous updates and expansion. This resource represents a vital foundation for studies in paleoclimate, paleoenvironment, and geochemistry, offering essential data for understanding long-term Earth-system processes. The data files described in this paper are available at https://doi.org/10.5281/zenodo.15117375 (Du et al., 2025a).

The transition from anaerobic to aerobic life was a pivotal adaptation in Earth's history, yet the timing and genomic drivers remain poorly resolved. Traditional approaches relying on oxygen-utilizing genes need improvement for obligate anaerobes and fragmentary environmental genomes, where gene absence may reflect poor assembly rather than phenotype. We developed a machine learning model (GBDT40-LR) to predict microbial oxygen requirements using 40 broadly conserved genes, 35 without direct oxygen roles. This approach overcomes incompleteness biases in environmental genomes. Applied to 80,787 bacterial genomes [including metagenome-derived assemblies (MAGs)], the model classified 42,014 aerobes and 38,775 anaerobes, enabling large-scale ancestral reconstruction. Molecular clock dating indicates an emergence of aerobic bacterium prior to the Great Oxidation Event (GOE, 2.5 to 2.3 Ga), likely around ~2.7 Ga. Aerobic lineages subsequently diversified during the GOE and Neoproterozoic Oxygenation Event (NOE, 0.8 to 0.55 Ga), with persistent anaerobe diversity across Earth's oxygenation. This establishes that aerobic bacteria originated planetary oxygenation, potentially by 200 to 400 My, providing insights into phenotypic evolution and prolonged anaerobe-aerobe coexistence.

Understanding the factors that have influenced the intensity and selectivity of extinction throughout Earth's history is important for explaining past biodiversity change and forecasting biotic responses to environmental change. Here, we investigated the role of coastline geometry and paleogeographic boundary conditions in shaping extinction risk for shallow-marine taxa over the past 540 million years. We show that interactions between the geographic distributions of taxa and the geometric configurations of continental margins consistently predict relative extinction risk: Taxa with potential dispersal pathways that are long relative to the range of latitude traversed-such as those that occur along east-west-oriented coastlines, islands, or inland seaways-consistently exhibit higher extinction risk than taxa with potential dispersal pathways that provide more direct latitude-traversing paths. This dispersal distance selectivity is amplified during mass extinction events and hyperthermal intervals, suggesting that geographic constraints become more important during periods of rapid climate change. Our results provide another mechanism that potentially contributes to the generally elevated extinction rates during the Paleozoic, an interval characterized by complex inland seas and a preponderance of east-west coastlines. These insights underscore the importance of considering paleogeographic context when interpreting past extinction patterns and provide empirical support for assumptions that underlie extinction risk assessments of extant species.

The great phytoplanktonic shift from green to red plastid lineage dominance in the early Mesozoic marks a primary producer revolution in marine ecosystems, facilitating the rise of modern ecosystems and impacting global carbon cycling and energy flows. The causes driving this evolutionary transition have been attributed to the changes in essential nutrients and the environmental crises of the Permian-Triassic mass extinction. Nonetheless, the underlying mechanisms driving this transition remain poorly understood. Here, we integrated culture experiments, molecular and physiological analyses, big data analysis, and phylogenomic dating analyses to uncover how environmental stresses influence algal physiology, thereby altering their evolutionary trajectories. We find that environmental and endogenous reactive oxygen species (ROS) collaboratively shape phytoplanktonic responses. The structural characteristics of red lineage phytoplankton enhance resistance to environmental ROS, facilitating physiological strategies that minimize endogenous ROS accumulation, thereby driving more adaptive evolutionary trajectories under environmental stresses in the early Mesozoic. The alignment of the turnover in diversification dynamics between the two lineages with paleoenvironmental shifts that triggered increased ROS production supports the role of ROS in driving this evolutionary transition. Our findings highlight ROS as a key underlying factor driving phytoplankton evolution, providing predictive insights into major biota-environment coevolutions throughout Earth's history.