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The influence of irradiance and interspecific differences on δ¹¹B, δ¹³C and elemental ratios in four coralline algae complexes from Aotearoa, New Zealand

We address the impact of light on four complexes of coralline red algae using boron and carbon isotopic signatures. We show that the four complexes up-regulated their δ¹¹B derived pH_CF relative to seawater by 0.6 to 0.8 pH unit but pH_CF was not directly impacted by light at the complex level. The differences in calcification between encrusting and branching complexes result from different photosynthetic regimes and carbon concentrating mechanisms, which would be inherent to morphologies.

The global importance of gas-phase peroxy radical accretion reactions for secondary organic aerosol loading

This work outlines an investigation into an understudied atmospheric chemical reaction pathway with the potential to form particulate pollution that has important impacts on air quality and climate. It suggests that this chemical pathway is responsible for a large fraction of the atmospheric particulate matter observed in tropical forested regions, but also highlights the need for further ambient and lab investigations to inform an accurate representation of this process in atmospheric models.

Clear-air turbulence derived from in situ aircraft observation – a weather feature-based typology using ERA5 reanalysis

Turbulence can occur in clear-air conditions at cruising altitude. From around 5000 clear-air turbulence events identified using aircraft measurements, nonlinear breaking of large-scale waves and rapidly ascending airstreams associated with cyclones are found concurrent with 40 % and 30 % of them respectively. The results further show that these weather systems may trigger turbulence by generating highly deformed flow or flow instability, improving our understanding of clear-air turbulence.

Conditions for instability in the climate–carbon cycle system

An increase in CO₂ in the atmosphere warms the climate through the greenhouse effect, but also leads to uptake of CO₂ by the land and ocean. However, the warming is also expected to suppress carbon uptake. If this suppression were strong enough, it could overwhelm the uptake of carbon, leading to a runaway feedback loop causing severe global warming. We find it is possible that this runaway could be relevant in complex climate models and even at the end of the last ice age.

Applications of Machine Learning and Artificial Intelligence in Tropospheric Ozone Research

Machine learning is being more widely used across environmental and climate science. This work reviews the use of machine learning in tropospheric ozone research, focusing on three main application areas in which significant progress has been made. Common challenges in using machine learning across the three areas are highlighted, and future directions for the field are indicated.

Including different mesozooplankton feeding strategies in a biogeochemical ocean model impacts global ocean biomass and carbon cycle

Mesozooplankton gather small current-drifting animals. They are very diverse and play key roles in the functioning of marine ecosystem and carbon cycle, especially through the production of rapidly sinking particles. Usually represented as one compartment, here we add three feeding strategies in an ocean biogeochemical model and investigate their impact on carbon cycle at global scale. We find distinct distributions between mesozooplankton types and diverse contributions to carbon export.

Uncovering the deep structure of the Koillismaa Layered Intrusion Complex, Finland using a novel 3D seismic survey

Solid Earth
DOI 10.5194/se-16-1437-2025
24 November 2025

We acquired and processed novel 3D seismic data to reveal the hidden structure of a deep rock formation in northeastern Finland. This study uncovered a complex, layered system rather than a simple magma channel, and identified a major fault that may influence mineral deposits. Our findings offer new tools and insights for exploring valuable underground resources in hard rock environments.

Conflict-induced ship traffic disruptions constrain cloud sensitivity to stricter marine pollution regulations

Militia attacks on ships in the Red Sea disrupted container ship traffic in 2024. We use these traffic changes to quantify how the cloud-altering properties of ship pollution decreased following sulfur regulations in 2020 with measurements of two types of ship pollution, one of which is sensitive to fuel composition and another which is not. Near Africa, cloud changes in 2024 were nearly as large as before the regulations, but only one-third as strong after accounting for increased traffic.

Novel oxalate-carbonate pathways identified in the tropical dry evergreen forest of Tamil Nadu, India

The oxalate-carbonate pathway, where trees and microbes store inorganic carbon as minerals, was studied on four tree species of the threatened tropical dry evergreen forest Indian forest. We used high-throughput sequencing of a gene to detect oxalate-degrading microbes. For all tree species, produced oxalate led to carbonate formation in soils and on wood. This carbon may be leached into water, suggesting a hidden source of inorganic carbon with implications for climate and conservation.

The frosty frontier: redefining the mid-latitude tropopause using the relative humidity over ice

We present a new technique to determine the tropopause based on the gradient of relative humidity over ice. This approach captures the character of the tropopause remarkably well, both in individual vertical profiles and in long-term averages, providing a consistent and physically meaningful representation of the transition between the troposphere and the stratosphere.

Recent history and future demise of Jostedalsbreen, the largest ice cap in mainland Europe

We model the historical and future evolution of the Jostedalsbreen ice cap in Norway, projecting substantial and largely irreversible mass loss for the 21st century, and that the ice cap will split into three parts. Further mass loss is in the pipeline, with a disappearance during the 22nd century under high emissions. Our study demonstrates an approach to model complex ice masses, highlights uncertainties due to precipitation, and calls for further research on long-term future glacier change.

An adaptable DTS-based parametric method to probe near-surface vertical temperature profiles at millimeter resolution

We present the the Fine Resolution Adaptable Distributed Temperature Sensing (FRADTS) method, which allows for mm-resolution probing of vertical temperature profiles, using coil-based distributed temperature sensing. The method is fully open source and parametric, such that unique field setups can be generated and reproduced. The method is extensively tested within a ~10cm grass canopy in a field campaign.

The TropoPause Composition TOwed Sensor Shuttle (TPC-TOSS): a new airborne dual platform approach for atmospheric composition measurements at the tropopause

Deployed on a Learjet as a tandem measurement platform during the TPEx I (TropoPause composition gradients and mixing Experiment) campaign in June 2024, the new TPC-TOSS (TropoPause Composition Towed Sensor Shuttle) system delivers high-resolution in situ data on ozone, aerosol, and key meteorological parameters. Laboratory and in-flight tests confirmed its precision and stability. Observed gradients near the tropopause reveal active mixing and transport processes in the tropopause region.

A statistical study of the O₂ atmospheric band aurora observed by the Swedish satellite MATS

This study uses images taken by the Swedish satellite MATS (Mesospheric Airglow Tomography and Spectroscopy) to conduct a statistical analysis of the molecular oxygen atmospheric band emissions in the aurora. This auroral emission can not be observed from the ground, making it one of the least understood auroral emissions. Our results provide a new dataset with information on the peak altitude, geomagnetic location, and auroral intensity of 378 events detected between February and April 2023.

IASI global radiometric uncertainty budget

This study establishes the global radiometric uncertainty budget of the Infrared Atmospheric Sounder Interferometer (IASI) instruments onboard Eumetsat first generation MetOp satellites. Major contributions to the budget arise from the correction of the analog non-linearity, the black body characterization, the scan mirror reflectivity and the background radiance instability. The estimated uncertainty remains relatively stable throughout the lifetime of the instruments.

The airborne chicago water isotope spectrometer: an integrated cavity output spectrometer for measurements of the HDO ∕ H₂O isotopic ratio in the Asian Summer Monsoon

The water molecule comes in several different varieties, which are nearly indistinguishable in daily life. However, slight differences between the water molecule types can be exploited to achieve better scientific understanding of parts of Earth's atmosphere. In this work we describe the design, construction, and operation of an instrument meant to measure these molecules aboard research aircraft up to altitudes of 20 km.

Progressive destabilization of a freestanding rock pillar in permafrost on the Matterhorn (Swiss Alps): Hydro-mechanical modeling and analysis

On 13 June 2023, a freestanding rock pillar on the Matterhorn collapsed after years of weakening. Our study examines this progressive destabilization by analyzing field data and integrating lab experiments into a hydro-mechanical model. We highlight the critical role of water infiltration into frozen rock, intensified by climate warming, as a widespread driver of the rising frequency of rockfalls in high mountain permafrost regions.

Reviews and syntheses: Artisanal and small-scale gold mining (ASGM)-derived mercury contamination in agricultural systems: what we know and need to know

Artisanal & Small-scale Gold Mining (ASGM) is rapidly expanding and mercury-use in the sector impacts agricultural systems near these spatially distributed activities. Mercury from ASGM is taken up by crops from both (1) air and (2) soil/water. Mercury in crops can also be passed to humans directly (eating crops) or via livestock/poultry after eating crops. Research in this area requires interdisciplinary, collaborative, and adaptable approaches to improve our comprehension of these impacts.

Drivers and impacts of westerly moisture transport events in East Africa

Anomalous westerly winds bring moisture into East Africa, increasing precipitation in the region. Using the first spatially unconstrained framework to detect this circulation and associated precipitation, we show westerlies contribute up to 60% of rainfall in Tanzania in January and February, and are more likely when the Madden Julian Oscillation and/or tropical cyclones are active over the Indian Ocean. This work highlights the complex interactions driving regional precipitation variability.

Automated mask generation in citizen science smartphone photos and their value for mapping plant species in drone imagery

We introduce an automated approach for generating segmentation masks for citizen science plant photos, making them applicable to computer vision models. This framework effectively transforms citizen science data into a data treasure for segmentation models for plant species identification in aerial imagery. Using automatically labeled photos, we train segmentation models for mapping tree species in drone imagery, showcasing their potential for forestry, agriculture, and biodiversity monitoring.

Observed and modeled Arctic airmass transformations during warm air intrusions and cold air outbreaks

Aircraft observations of air parcels moving into and out of the Arctic are reported. From the data, heating and cooling as well as drying and moistening of the air masses along their way into and out of the Arctic could be measured for the first time. These data are used to evaluate if weather prediction models are able to accurately represent these air mass transformations. This work helps to model the future Arctic climate changes, which may have an impact for mid-latitude weather as well.

Reviews and syntheses: Best practices for the application of marine GDGTs as proxy for paleotemperatures: sampling, processing, analyses, interpretation, and archiving protocols

Many academic laboratories worldwide process environmental samples for analysis of membrane lipid molecules of archaea, for the reconstruction of past environmental conditions. However, the sample workup scheme involves many steps, each of which has a risk of contamination or bias, affecting the results. This paper reviews steps involved in sampling, extraction and analysis of lipids, interpretation and archiving of the data. This ensures reproducible, reusable, comparable and consistent data.

Holocene land cover change in North America: continental trends, regional drivers, and implications for vegetation–atmosphere feedbacks

Holocene vegetation–atmosphere interactions provide insight into intensifying land use impacts and the Holocene Conundrum: a mismatch between data- and model-inferred temperature. Using pollen records and statistical modeling, we reconstruct Holocene land cover for North America. We determine patterns and magnitudes of land cover changes across scales. We attribute land cover changes to ecological, climatic, and human drivers. These reconstructions provide benchmarks for Earth system models.

Milankovitch theory “as an initial value problem”: Implications of the long memory of ice advection

We describe a so far unrecognized physical phenomenon of orbital forcing modifying the terrestrial physics in such a way that instead of erasing the memory of initial conditions this memory is extended and initial values become major governing parameters.

Estimates of Atlantic meridional heat transport from spatiotemporal fusion of Argo, altimetry, and gravimetry data

Understanding how heat moves through the ocean is crucial to predicting future climate change confidently. This requires accurate records of heat transport throughout the ocean, but these are challenging to obtain by direct ocean observation. Here, we combine in situ and satellite-based observations to generate estimates of meridional heat transport for the period 2004–2020 at 3-month resolution across the Atlantic Ocean with improved accuracy compared to existing indirectly inferred estimates.

Global and regional sea-surface temperature changes over the Marine Isotopic Stage 9e and Termination IV

To better understand climate change in past warm periods, we studied global ocean temperature during an interglacial period about 330,000 years ago. Combining 98 records on common timeline, we found regional differences in the timing and amplitude of changes, which smoothed the global signal. We also show that the deglacial warming rate was about three times lower than today's global warming rate.

Formation of mega-scale glacial lineations far inland beneath the onset of the Northeast Greenland Ice Stream

The subglacial landforms beneath actively fast-flowing ice in Greenland have not been explored in detail, as digital elevation models have not had a high enough resolution to see these features. We use swath radar imaging to visualise landforms at the onset of an ice stream, revealing mega-scale glacial lineations, that would usually be assumed to be indicative of faster ice flow than the current velocities. Interpretation of the landscape also gives an indication of the properties of the bed.

Properties of large-amplitude kilometer-scale field-aligned currents at auroral latitudes, as derived from Swarm satellites

By using magnetic field recordings sampled at 50 Hz by Swarm A and C satellites around the quasi-coplanar orbit configuration, near 1 October 2021, we investigate the properties of kilometer-scale field-aligned currents (FACs) at auroral latitudes. The kilometer-scale (0.2-5 km) FACs exhibit short-lived (<1 s) randomly appearing large current density spikes (partly exceeding 100 µA m-2). Preferred occurrences are the noon to prenoon (nightside to dusk) sector around 80° (70°) MLat, respectively.

Thwaites Eastern Ice Shelf cavity observations reveal multiyear sea ice dynamics and deepwater warming in Pine Island Bay, West Antarctica

Thwaites Glacier is retreating due to warm ocean water melting it from below, but its thick ice shelf makes this heat hard to monitor. Using hot-water drilling, we placed sensors beneath the floating ice, revealing how surface freezing in Pine Island Bay influences heat at depth. Alongside gradual warming, we found bursts of heat that could speed up melting at the grounding zone, which may become more common as sea ice declines.

Review of interactive open-access publishing with community-based open peer review for improved scientific discourse and quality assurance

Over 25 years, the European Geosciences Union (EGU) has demonstrated the success, viability and benefits of interactive open-access (OA) publishing with public peer review in its journals, its publishing platform EGUsphere and virtual compilations. The article summarizes the evolution of the EGU/Copernicus publications and of OA publishing with interactive public peer review at large by placing the EGU/Copernicus publications in the context of current and future global open science.

The role of the tropical carbon balance in determining the large atmospheric CO₂ growth rate in 2023

The year 2023 saw unexpectedly large global atmospheric CO₂ growth. Satellite data reveal a role for increased tropical emissions. Larger emissions over eastern Brazil can be explained by warmer temperatures, which has led to exceptional drought, while hydrological changes play more of a role in emission increases elsewhere in the tropics. Broadly, we find that this situation continues into 2024.

Effects of geomagnetic mirror force and pitch angles of precipitating electrons on ionization of the polar upper atmosphere

The magnetic mirror force bends the orbits of electrons precipitating into the atmosphere. It has been suggested that relativistic electrons make much less ionization due to the force than if it did not exist, but the actual effectivity in the atmospheric electron density has not been revealed. We used conjugated observational data from the ELFIN (Electron Losses and Fields INvestigation) satellite and the EISCAT (European Incoherent SCATter scientific radar system) Tromsø radar to find that the electron density decreased by about 40 % at 80 km altitude because of the force.

nextGEMS: entering the era of kilometer-scale Earth system modeling

The Next Generation of Earth Modeling Systems project (nextGEMS) developed two Earth system models that use horizontal grid spacing of 10 km and finer, giving more fidelity to the representation of local phenomena, globally. In its fourth cycle, nextGEMS simulated the Earth System climate over the 2020–2049 period under the SSP3-7.0 scenario. Here, we provide an overview of nextGEMS, insights into the model development, and the realism of multi-decadal, kilometer-scale simulations.

Experiences and Lessons Learned from Designing and Testing of an Air System and a Drilling Fluid Circulation System Adapted for Subglacial Bedrock Sampling in Antarctica

Geoscientific Instrumentation, Methods and Data Systems
DOI 10.5194/gi-14-277-2025
23 October 2025

A multi-process drilling system (MPDS), comprising an air system and a drilling-fluid circulation system (DFCS) was developed in China for subglacial bedrock sampling. The air system and DFCS were highly integrated in 20 ft container for easy transportation and assembly. Both systems were tested in China and Antarctica. The experiences and lessons learned in designing and testing would be helpful to promote the development of subglacial bedrock drilling technology.

Insights into mesoscale eddy dynamics: a three-dimensional perspective on potential density anomalies

Mesoscale eddies, characterized by rotating currents, are ubiquitous in the ocean. However, their three-dimensional structure remains poorly observed and analyzed, with transport estimates often relying on approximations. To better quantify their shape, we propose a new theoretical framework based on geophysical fluid dynamics and apply it to field observations.

Representing soil landscapes from digital soil mapping products – helping the map to speak for itself

SOIL
DOI 10.5194/soil-11-849-2025
21 October 2025

Soil maps are useful for many applications, e.g., hydrology, agriculture, ecology, and civil engineering. The dominant mapping method is Digital Soil Mapping (DSM), which uses training observations and machine-learning to predict per-pixel. Accuracy is assessed by statistical evaluation at known points, but soils occur in spatial patterns. We present methods for helping the map to "speak for itself" to reveal patterns of the soil landscape.

MOSAiC studies of long-lasting mixed-phase cloud events and analysis of the liquid-phase properties of Arctic clouds

We studied the water and ice phases of Arctic mixed-phase clouds (MPCs) using dual FOV polarization lidar and Doppler radar on board Polarstern during the MOSAiC expedition. Two long-lasting Arctic MPCs and year-round statistics show persistent droplet activation and dominant immersion freezing, indicating well-filled cloud condensation nuclei and ice-nucleating particle reservoirs. These findings help explain MPC longevity and may improve cloud life cycle representation in weather and climate models.

Estimating return periods for extreme events in climate models through Ensemble Boosting

Weather extremes have become more frequent due to climate change. It is therefore crucial to understand them, but since they are rarer than average weather, they are challenging to study. Ensemble Boosting (EB) is a tool that generates extreme climate model events efficiently, but without directly estimating their probability. Here, we present a method to recover these probabilities for a global climate model. EB can thus now be used to find extremes with meaningful statistical information.

Mercury contamination in staple crops impacted by artisanal and small-scale gold mining (ASGM): stable Hg isotopes demonstrate dominance of atmospheric uptake pathway for Hg in crops

Air, soil, and three common staple crops were assessed at an artisanal and small-scale gold mining (ASGM) processing site, and mercury (Hg) contamination was observed at a farm ≈ 500 m from the processing site. Of the crop tissues examined, foliage had the highest concentrations. Mercury stable isotopes indicate uptake of mercury from the air to the foliage as the dominant uptake pathway. Using typical dietary data for Nigerians, Hg intake from these crops was below reference dose levels and generally safe for consumption.

AR6 updates to RF by GHGs and aerosols lowers the probability of accomplishing the Paris Agreement compared to AR5 formulations

We show that recent assessed updates to the future abundance and radiative forcing (RF) of greenhouse gases (GHGs) and tropospheric aerosols result in a 0.2 to 0.4 ⁰C rise in global mean surface temperature by the end of the century, relative to prior projections. For society to have confidence in achieving the 2 ⁰C warming limit of the Paris Agreement, the RF due to GHGs and aerosols must be placed close to the primary 2.6 W m⁻² Shared Socioeconomic Pathway scenario (SSP1−2.6) over the coming decades.

TICOI: an operational Python package to generate regular glacier velocity time series

While global annual glacier velocities are openly accessible, sub-annual velocity time series are still lacking. This hinders our ability to understand flow processes and the integration of these observations in numerical models. We introduce an open source Python package called TICOI (Temporal Inversion using linear Combinations of Observations, and Interpolation) to fuse multi-temporal and multi-sensor image-pair velocities produced by different processing chains to produce standardized sub-annual velocity products.

A dilatant visco-elasto-viscoplasticity model with globally continuous tensile cap: stable two-field mixed formulation

We present a simple plasticity model that can be used for robust modeling of strain localization in both shear and tensile failure regimes. The new model overcomes the difficulty related to combining these regimes and enables for particularly simple and reliable numerical implementation, which delivers regularized solutions that are insensitive to mesh resolution. We describe algorithmic details and demonstrate the applications to a number of relevant strain localization problems.

A tracer study for the development of in-water monitoring, reporting, and verification (MRV) of ship-based ocean alkalinity enhancement

Ocean alkalinity enhancement (OAE) is a carbon removal approach in which alkaline materials are added to the marine environment, increasing the ocean's ability to store carbon dioxide. We conducted an open-water experiment releasing and tracking a fluorescent water tracer. Under the right conditions, in-water monitoring of OAE does appear to be possible. We conclude with a series of practical recommendations for open-water OAE monitoring.

Mapping the safe operating space of marine ecosystems under contrasting emission pathways

Anthropogenic greenhouse gas emissions significantly impact ocean ecosystems through climate change and acidification, leading to either progressive or abrupt changes. This study maps the crossing of physical and ecological limits for various ocean impact metrics under three emission scenarios. Using Earth system models, we identify when these limits are exceeded, highlighting the urgent need for ambitious climate action to safeguard the world's oceans and ecosystems.

Tipping points in ocean and atmosphere circulations

In this work, we draw on palaeo-records, observations, and modelling studies to review tipping points in the ocean overturning circulations, monsoon systems, and global atmospheric circulations. We find indications for tipping in the ocean overturning circulations and the West African monsoon, with potentially severe impacts on the Earth system and humans. Tipping in the other considered systems is regarded as conceivable but is currently not sufficiently supported by evidence.

Place-based science from Okinawa: 18th-century climate and geology recorded in Ryukyuan classical music

Indigenous Ryukyuan music records the 18th-century climate and geology of the Ryukyu Kingdom (21st-century Okinawa Prefecture, Japan). By collaborating with Ryukyuan cultural practitioners, we find that two seafaring songs detail the winds, ocean currents, and volcanoes that historical voyagers faced during envoys to Kyushu, Japan. Educators can use such observations in place-based learning to increase environmental science engagement in 21st-century Okinawa and the Okinawan diaspora worldwide.

Extensive fire-driven degradation in 2024 marks worst Amazon forest disturbance in over 2 decades

The Amazon forest faces increasing wildfires due to extreme drought and human activity. In 2024, disturbances surged by 152 %, hitting a 20-year high. Forest degradation from fires grew by over 400 %, exceeding that from deforestation. Brazil and Bolivia were hit hardest. These fires released huge amounts of CO₂, 7 times more than in recent years, pushing the Amazon towards a dangerous tipping point. Urgent action is needed to prevent irreversible harm.

Increased future ocean heat uptake constrained by Antarctic sea ice extent

Future projections of global ocean heat uptake (OHU) strongly differ between climate models. Here, we reveal an observational constraint on future OHU based on historical Antarctic sea ice extent observations. This emergent constraint is based on a coupling between sea ice, deep- and surface ocean temperatures, and cloud feedback. It implies an upward correction of 2024–2100 global OHU projections by up to 14 % and suggests that previous constraints have underestimated future warming.

The coupled oxygen and carbon dynamics in the subsurface waters of the Gulf and Lower St. Lawrence Estuary and implications for artificial oxygenation

We combine two decades of oxygen data with new carbon observations and a tracer-informed model to quantify oxygen loss and carbon buildup in the deep waters of the Gulf and Lower St. Lawrence Estuary. We then test a novel idea: reoxygenating these waters with the oxygen produced as a by-product from green-hydrogen production. Our results suggest this could significantly reduce hypoxia, though full recovery would require larger inputs.

Insights from hailstorm track analysis in European climate change simulations

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-25-3693-2025
1 October 2025

Hailstorms can cause severe damage to homes, crops, and infrastructure. Using high-resolution climate simulations, we tracked thousands of hailstorms across Europe to study future changes. Large hail will become more frequent, hail-covered areas will expand, and instances of extreme hail combined with heavy rain will double. These shifts could increase risks for communities and businesses, highlighting the need for better preparedness and adaptation.