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1950 items found

10 20 50

flat10MIP: an emissions-driven experiment to diagnose the climate response to positive, zero and negative CO₂ emissions

This study investigates how climate models warm in response to simplified carbon emissions trajectories, refining the understanding of climate reversibility and commitment. Metrics are defined for warming response to cumulative emissions and for the cessation of emissions or ramp-down to net-zero and net-negative levels. Results indicate that previous concentration-driven experiments may have overstated the Zero Emissions Commitment due to emissions rates exceeding historical levels.

Synoptic observation of a full mesoscale eddy lifetime and its secondary instabilities in the Gulf of Mexico

Ocean Science
DOI 10.5194/os-21-1933-2025
4 September 2025

Oceanic eddies are giant swirling currents that help transport heat, nutrients, and pollutants across the ocean. However, their life cycle has never been observed in detail. Using new satellite data, we tracked an intense eddy in the Gulf of Mexico, describing its life cycle from birth during a 6-month period. Our observations reveal small-scale turbulence surrounding it and interactions with other structures that shape its evolution, validating decades of numerical studies.

CYCLOPs: a Unified Framework for Surface Flux-Driven Cyclones Outside the Tropics

Storms strongly resembling hurricanes are sometimes observed to form well outside the tropics, even in polar latitudes. They behave capriciously, developing very rapidly and then dying just as quickly. We show that strong dynamical processes in the atmosphere can sometimes cause it to become much colder locally than the underlying ocean, creating the conditions for hurricanes to form but only over small areas and for short times. We call the resulting storms "CYCLOPs".

A climate suitability index for species distribution modelling applied to terrestrial arthropods in the Mediterranean region

Climate change threatens biodiversity, especially that of arthropods, by altering species' habitats and ecological roles. This study presents a proof of concept for a novel index that models species distributions based on climatic niches, using regional climate model data and focusing on Mediterranean arthropods. The index enables quick assessments of species' climate resilience and offers potential applications for projecting ecological impacts of future climate changes.

Calibration and performance evaluation of PM _2.5 and NO ₂ air quality sensors for environmental epidemiology

This study evaluates PM _2.5 and NO ₂ sensors for their use in health studies. Sensors were calibrated using data from reference instruments, and regression and machine learning models were evaluated, identifying opportunities and limitations in model transferability in both indoor and outdoor environments and showcasing the importance of integrating metadata such as activity logs and diffusive tubes to improve data validation and interpretation during deployment in the houses of the participants.

Turning regret into future disaster preparedness with no regrets

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-25-2929-2025
29 August 2025

What do we regret about our disaster preparedness? This paper explores the regrets of 438 citizens who were affected by flooding in Germany in 2021. It shows that regret can primarily be associated with inaction (instead of actions), which contrasts with psychological studies from fields other than disaster science. The findings of this study suggest that the no-regret approach could be a suitable framework for moving towards longer-term disaster preparedness to reduce future regrets.

Impact-based temporal clustering of multiple meteorological hazard types in southwestern Germany

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-25-2885-2025
27 August 2025

Using loss data, we assess when and how single and multiple types of meteorological extremes (river floods and heavy rainfall events, windstorms and convective gusts, and hail) are related. We find that the combination of several types of hazards clusters robustly on a seasonal scale, whereas only some single hazard types occur in clusters. This can be associated with higher losses compared to isolated events. We argue for the relevance of jointly considering multiple types of hazards.

A numerical model of microplastic erosion, transport, and deposition for fluvial systems

Rivers transport microplastic pollution from its source to its eventual marine sink. Rivers are not simple conveyor belts of this pollution. Microplastic will become entrained within the sediments, becoming part of the river catchment environment. We develop a reduced complexity model to capture the transport and deposition of microplastic. By comparing our model to observations from the Têt River, France, we find that large quantities of microplastic must be stored within the river sediments.

Southern Hemisphere tree rings as proxies to reconstruct Southern Ocean upwelling

The Southern Ocean carbon sink is a balance between two opposing forces: CO₂absorption at mid-latitudes and CO₂ outgassing at high latitudes. Radiocarbon analysis can be used to constrain the latter, as upwelling waters outgas old CO₂, diluting atmospheric radiocarbon content. We present tree-ring radiocarbon measurements from Aotearoa / New Zealand and Chile. We show that low radiocarbon in Aotearoa / New Zealand’s Motu Ihupuku / Campbell Island is linked to outgassing in the critical Antarctic Southern Zone.

Groundwater recharge in Brandenburg is declining – but why?

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-25-2783-2025
19 August 2025

Brandenburg is among the driest federal states in Germany. The low groundwater recharge (GWR) is fundamental to both water supply and the support of natural ecosystems. In this study, we show that the decline of observed discharge and groundwater tables since 1980 can be explained by climate change in combination with an increasing leaf area index. Still, simulated GWR rates remain highly uncertain due to the uncertainty in precipitation trends.

Insights into supraglacial lake drainage dynamics: triangular fracture formation, reactivation and long-lasting englacial features

We study the evolution of a massive lake on the Greenland Ice Sheet using satellite and airborne data and some modelling. The lake is emptying rapidly. Water flows to the glacier’s base through cracks and triangular-shaped moulins that remain visible over the years. Some of them become reactivated. We find features inside the glacier that stem from drainage events with a width of even 1 km. These features are persistent over the years, although they are changing in shape.

Light scattering and microphysical properties of atmospheric bullet rosette ice crystals

Understanding the interaction between cirrus clouds and solar radiation is critical for modeling the Earth’s climate. A common crystal type found in cirrus clouds is the bullet rosette. Here, atmospheric bullet rosettes measured from jet aircraft are analyzed for their morphological and radiative properties. Atmospheric bullet rosettes are found to be more morphologically complex than previously assumed. This complexity has a significant impact on their radiative properties.

Warnings based on risk matrices: a coherent framework with consistent evaluation

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-25-2657-2025
13 August 2025

Our research presents a new method for determining warning levels for any hazard. Using risk matrices, our framework addresses issues found in other approaches. Illustrative examples demonstrate how the approach works. A powerful method for evaluating warning accuracy is given, allowing for a cycle of continuous improvement in warning services. This research is relevant to a broad audience, from those who develop forecast systems to practitioners who issue or communicate warnings.

Invited perspectives: Thunderstorm intensification from mountains to plains

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-25-2629-2025
8 August 2025

Strong thunderstorms have been studied mainly over flat terrain in the past. However, they are particularly frequent near European mountain ranges, so observations of such storms are needed. This article gives an overview of our existing knowledge on this topic and presents plans for a large European field campaign with the goals to fill the knowledge gaps, validate tools for thunderstorm warnings, and improve numerical weather prediction near mountains.

Consequences of the Aral Sea restoration for its present physical state: temperature, mixing, and oxygen regime

The Aral Sea is both an example of large-scale environmental degradation caused by human activity and a message of hope through its partial restoration. Our study shows that the restored part of the Aral Sea is now healthy in terms of vertical mixing and oxygenation. However, small perturbations of water level or transparency could significantly alter the entire ecosystem. The results contribute to understanding the consequences of large-scale lake management worldwide.

Subsurface manifestation of marine heat waves in the southwestern Indian Ocean

Marine heat waves (MHWs) are prolonged periods of extreme ocean temperatures with significant impacts on marine ecosystems. Much research has focused on surface MHWs, but less is known about their subsurface extent. This study uses satellite and in situ data to investigate MHWs in the southwestern Indian Ocean (SWIO). We find that MHWs in the SWIO are closely linked to mesoscale eddies and that strong temperature anomalies extend below surface-identified MHWs.

A Bayesian framework for inferring regional and global change from stratigraphic proxy records (StratMC v1.0)

The chemistry of sedimentary rocks is used to reconstruct past changes in Earth’s climate and biogeochemical cycles. Reconstructing global change requires merging stratigraphic proxy records from many locations, each of which may be incomplete, time-uncertain, and influenced by both global and local processes. StratMC uses Bayesian modeling to see through this complexity, building more accurate and testable reconstructions of global change from stratigraphic data.

Opinion: The role of AerChemMIP in advancing climate and air quality research

The Aerosol Chemistry Model Intercomparison Project (AerChemMIP) aimed to quantify the climate and air quality impacts of aerosols and chemically reactive gases. We review its contribution to AR6 (Sixth Assessment Report of the Intergovernmental Panel on Climate Change) and the wider understanding of the role of these species in climate and climate change. We identify challenges and provide recommendations to improve the utility and uptake of climate model data, detailed summary tables of CMIP6 models, experiments, and emergent diagnostics.

Characterization of the 1966 Camp Century subglacial core: a multiscale analysis

The Camp Century subglacial core stores information about past climates and glacial and interglacial processes in northwestern Greenland. In this study, we investigated the core archive, making large-scale observations using computed tomography (CT) scans and micron-scale observations observing physical and chemical characteristics of individual grains. We find evidence of past ice-free conditions, weathering processes during warmer periods, and past glaciations.

Quantifying the soil sink of atmospheric hydrogen: a full year of field measurements from grassland and forest soils in the UK

We measured soil hydrogen (H₂) fluxes from two field sites, a managed grassland and a planted deciduous woodland, with flux measurements of H₂ covering full seasonal cycles. We estimate annual H₂ uptake of −3.1 ± 0.1 and −12.0 ± 0.4 kg H₂ ha⁻¹ yr⁻¹ for the grassland and woodland sites, respectively. Soil moisture was found to be the primary driver of H₂ uptake, with the silt/clay content of the soils providing a physical barrier which limited H₂ uptake.

Leveraging the satellite-based climate data record CLARA-A3 to understand the climatic trend regimes relevant for solar energy applications over Europe

By compositing trends in multiple climate variables, this study presents emerging regimes that are relevant for solar energy applications. It is shown that the favourable conditions for exploiting solar energy are emerging during spring and early summer. The study also underscores the increasingly important role of clouds in regulating surface solar radiation as the aerosol concentrations are decreasing over Europe and the societal value of satellite-based climate monitoring.

asQ: parallel-in-time finite element simulations using ParaDiag for geoscientific models and beyond

Effectively using modern supercomputers requires massively parallel algorithms. Time-parallel algorithms calculate the system state (e.g. the atmosphere) at multiple times simultaneously and have exciting potential but are tricky to implement and still require development. We have developed software to simplify implementing and testing the ParaDiag algorithm on supercomputers. We show that for some atmospheric problems it can enable faster or more accurate solutions than traditional techniques.

Thermal state of permafrost in the Central Andes (27–34° S)

This study presents the first regional compilation of borehole temperature data from high-altitude permafrost sites in the Andes, providing a baseline of ground thermal conditions. Data from 53 boreholes show thermal characteristics similar to other mountain permafrost areas, but uniquely shaped by Andean topo-climatic conditions. The study emphasizes the need for ongoing monitoring and is a notable collaboration between industry, academia, and regulators in advancing climate change research.

Marine snow morphology drives sinking and attenuation in the ocean interior

Key parameters representing the gravity flux in global models are sinking speed and vertical attenuation of exported material. We calculate, for the first time, these parameters in situ in the ocean for six intermittent blooms followed by export events using high-resolution (3 d) time series of 0–1000 m depth profiles from imaging sensors mounted on an Argo float. We show that sinking speed depends not only on size but also on the morphology of the particles, with density being an important property.

Occupancy history influences extinction risk of fossil marine microplankton groups

We examine how change in a species’ geographic range size over time influences that species’ extinction risk. We analyze instantaneous range size and range size change and how these terms relate to extinction risk in marine microplankton. We find that both the instantaneous range size and the change in range size are informative predictors of extinction. Using predictive models, we also assess extinction probability in four extant groups.

The value of hydroclimatic teleconnections for snow-based seasonal streamflow forecasting in central Asia

Seasonal streamflow forecasts for snowmelt-dominated catchments often rely on snowpack data, which are not always available and are prone to errors. Our study evaluates near-real-time global snow estimates and climate oscillation indices for predictions in the data-scarce mountains of central Asia. We show that climate indices can improve prediction accuracy at longer lead times, help offset snow data uncertainty, and enhance predictions where streamflow depends on in-season climate variability.

Calibrated sea level contribution from the Amundsen Sea sector, West Antarctica, under RCP8.5 and Paris 2C scenarios

Glaciers in the Amundsen Sea region of Antarctica have been retreating and losing mass, but their future contribution to global sea level rise remains highly uncertain. We use an ice sheet model and uncertainty quantification methods to evaluate the probable range of mass loss from this region for two future climate scenarios. We find that the rate of ice loss until 2100 will likely remain similar to present-day observations, with little sensitivity to climate scenario over this short time frame.

Delineating the technosphere: definition, categorization, and characteristics

The technosphere – including buildings, infrastructure, and all other non-living human creations – is a major part of our planet, but it is not often considered as an integrated part of Earth system processes. Here we propose a refined definition of the technosphere, intended to help with integration. We also characterize the functional end uses, map the global distribution, and discuss the catalytic properties that underlie the exponential growth of the trillion tonne technosphere.

Distribution of alkylamines in surface waters around the Antarctic Peninsula and Weddell Sea

During the PolarChange expedition, volatile alkylamines, important players in nitrogen cycling and cloud formation, were measured in Antarctic waters using a high-sensitivity method. Trimethylamine was the dominant alkylamine in marine particles, associated with nanophytoplankton. Dissolved dimethylamine likely originated from trimethylamine degradation, while diethylamine sources remain unclear. These findings confirm the biological origin of alkylamines in polar marine microbial food webs.

Observational constraints suggest a smaller effective radiative forcing from aerosol–cloud interactions

This study addresses the long-standing challenge of quantifying the impact of aerosol–cloud interactions. Using satellite observations, reanalysis data, and a “perfect-model” cross-validation, we show that explicitly accounting for aerosol–cloud droplet activation rates is key to accurately estimating ERFaci (effective radiative forcing due to aerosol–cloud interactions). Our results indicate a smaller and less uncertain ERFaci than previously assessed, implying the reduced role of aerosol–cloud interactions in shaping climate sensitivity.

Simulating vertical phytoplankton dynamics in a stratified ocean using a two-layered ecosystem model

Phytoplankton contribute to half of Earth’s primary production, but not a lot is known about subsurface phytoplankton, living at the base of the sunlit ocean. We develop a two-layered box model to simulate phytoplankton seasonal and interannual variations in different depth layers of the ocean. Our model captures seasonal and long-term trends of the two layers, explaining how they respond to a warming ocean, furthering our understanding of how phytoplankton are responding to climate change.

Long-term observations of atmospheric CO₂ and CH₄ trends and comparison of two measurement systems at Pallas-Sammaltunturi station in Northern Finland

This paper presents long-term observations of atmospheric CO₂ and CH₄ mole fractions and a comparison of two permanent and two mobile measurement systems located in Northern Finland. Furthermore, the observed mole fractions are compared against the mean marine boundary layer product for the Northern Hemisphere. The comparisons of all the systems show good agreement in relation to the World Meteorological Organization/Global Atmosphere Watch network compatibility goal limits for CO₂ and CH₄.

Evidence for multi-rifting in the Variscan–Alpine cycle transition: insights from the European western Southern Alps

We address the transition between the Paleozoic Variscan and Alpine Mesozoic–Cenozoic cycles using tectono-stratigraphy and thermochronology. This transition unfolds through a multi-phase rifting history. An initial rifting stage occurred in the early Permian, followed in the early–middle Permian by a phase of transcurrent tectonics. This was succeeded by a period of erosion/non-deposition in the middle Permian. Crustal stretching in the Middle Triassic marked the onset of the Alpine cycle.

Local versus far-field control on South Pacific Subantarctic mode water variability

Subantarctic mode water in the South Pacific Ocean is important due to its role in the uptake and transport of anthropogenic heat and carbon. The Subantarctic mode water region can be split into two pools using mixed-layer-depth properties. Sensitivity experiments are used to understand the effects of heating and wind on each pool. It is found that the optimal conditions to form large amounts of Subantarctic mode water in the South Pacific are local cooling and upstream warming combined.

First observations of continuum emission in dayside aurora

We studied the first broad band emissions, called continuum, in the dayside aurora. They are similar to Strong Thermal Emission Velocity Enhancement (STEVE) with white-, pale-pink-, or mauve-coloured light. But unlike STEVE, they follow the dayside aurora forming rays and other dynamic shapes. We used ground optical and radar observations and found evidence of heating and upwelling of both plasma and neutral air. This study provides new information on conditions for continuum emission, but its understanding will require further work.

Is drought protection possible without compromising flood protection? Estimating the potential dual-use benefit of small flood reservoirs in southern Germany

In this paper, we use models to demonstrate that even small flood reservoirs – which capture water to avoid floods downstream – can be repurposed to release water in drier conditions without affecting their ability to protect against floods. By capturing water and releasing it once levels are low, we show that reservoirs can greatly increase the water available in drought. Having more water available to the reservoir, however, is not necessarily better for drought protection.

Qualitative risk assessment of sensitive infrastructures at the local level: flooding and heavy rainfall

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-25-2097-2025
4 July 2025

In post-disaster reconstruction, emphasis should be placed on critical and sensitive infrastructures. In Germany, as in other countries, sensitive infrastructures have not yet been focused on; therefore, we developed a method for determining the risk that sensitive infrastructures are facing in the context of riverine and pluvial flooding. The easy-to-use assessment framework can be applied to various sensitive infrastructures, e.g., to qualify and accelerate decisions in the reconstruction process.

Phylogeochemistry: exploring evolutionary constraints on belemnite rostrum element composition

Belemnite rostrum geochemistry is used as a proxy in palaeoceanography. Evolutionary patterns in element ratios (Mg/Ca, Sr/Ca, Mn/Ca, and Fe/Ca) from belemnite rostra based on a literature dataset are assessed. These proxy data reflect a complex interplay between evolutionary, ontogenetic, environmental, kinetic, and diagenetic effects. We coin the new term “phylogeochemistry” for this interdisciplinary research field.

The satellite chlorophyll signature of Lagrangian eddy trapping varies regionally and seasonally within a subtropical gyre

Eddies are rotating ocean vortices up to hundreds of kilometers in diameter that stimulate phytoplankton blooms. We used satellite data and simulations of currents to examine the effect of eddy trapping strength on phytoplankton concentration in the open North Pacific Ocean. Coherent eddies trap phytoplankton, while “leaky” ones have lower concentrations because they mix with surrounding waters. However, contrary to previous theory, eddy-trapped blooms are more prominent in southern latitudes.

Long-term prediction of the Gulf Stream meander using OceanNet: a principled neural-operator-based digital twin

The Gulf Stream is a prominent oceanic feature in the northwestern Atlantic Ocean that influences weather patterns in the Northern Hemisphere and is notoriously difficult to predict. We present a machine learning model, OceanNet, to predict the position of the Gulf Stream months in advance. OceanNet is able to perform a 120 d prediction 4 000 000 times faster than traditional methods of ocean modeling with great accuracy.

Using 3D observations with high spatio-temporal resolution to calibrate and evaluate a process-focused cellular automaton model of soil erosion by water

SOIL
DOI 10.5194/soil-11-413-2025
16 June 2025

This study develops a new method to improve the calibration and evaluation of models that predict soil erosion by water. By using advanced imaging techniques, we can capture detailed changes in the soil surface over time. This helps improve models that forecast erosion, especially as climate change creates new and unpredictable conditions. Our findings highlight the need for more precise tools to better model erosion of our land and environment in the future.

The potential of observing atmospheric rivers with Global Navigation Satellite System (GNSS) radio occultation

The study investigates using Global Navigation Satellite System Radio Occultation (GNSS-RO) to analyze the vertical structure of humidity in atmospheric rivers (ARs). Specific humidity and integrated water vapor from the COSMIC Data Analysis and Archive Center (CDAAC) and the Wegener Center (WEGC) are compared with the Special Sensor Microwave Imager/Sounder (SSMIS), showing that GNSS-RO adds vertically resolved data. Despite a slight low bias, combining GNSS-RO and SSMIS improves AR analysis.

Implications of reduced-complexity aerosol thermodynamics on organic aerosol mass concentration and composition over North America

We implemented the BAT-VBS (Binary Activity Thermodynamics volatility basis set) aerosol thermodynamics model in the GEOS-Chem chemical transport model to efficiently account for organic aerosol water uptake, nonideal mixing, and impacts on the gas–particle partitioning of semi-volatile organics. Compared to GEOS-Chem’s complex (dry) scheme, we show that the BAT-VBS model can predict substantial enhancements in organic aerosol mass concentration at moderate-to-high relative humidity.

GC Insights: Consistency in pyrocartography starts with color

Fire progression maps (FPMs) provide information regarding wildland fire spread (progress) through time to broad audiences. However, information regarding the best use of color to denote fire progression via maps is limited. This can potentially limit a map’s ability to effectively communicate information by creating inconsistent messaging and accessibility challenges. Here, I provide color map recommendations to open a discussion towards consistent and accessible fire progression mapping.

Leaping and vortex motion of the shock aurora toward the late evening sector observed on 26 February 2023

Our research explores the shock aurora, which is typically observed on the dayside due to the rapid compression of the Earth’s magnetic field. We observed this rare aurora on the nightside, a region where such events are difficult to detect. Using ground-based cameras, we identified new features, including leaping and vortex-like patterns. These findings offer a fresh insight into the interactions between the solar wind and the magnetosphere, enhancing our understanding of space weather and its effects.

Sedimentary ancient DNA insights into foraminiferal diversity near the grounding line in the western Ross Sea, Antarctica

Ancient foraminiferal DNA is studied in five Antarctic cores with sediments up to 25 kyr old. We use a standard and a new, more effective marker, which may become the next standard for paleoenvironmental studies. Much less diverse foraminifera occur on slopes of submarine moraines than in open-marine settings. Soft-walled foraminifera, not found in the fossil record, are especially abundant. There is no foraminiferal DNA in tills, suggesting its destruction during glacial redeposition.

Explaining the period fluctuation of the quasi-biennial oscillation

The paper addresses a fundamental but unresolved question about the tropical stratospheric wind oscillation: why does the period of the oscillation fluctuate irregularly? We use global reanalysis data to provide evidence that the oscillation period is primarily modulated by seasonal variations in small-scale atmospheric wave activity. The findings have implications for seasonal and climate predictions.

Mean ocean temperature change and decomposition of the benthic δ¹⁸O record over the past 4.5 million years

We reconstruct changes in mean ocean temperature (ΔMOT) over the last 4.5 Myr. We find that the ratio of ΔMOT to changes in global mean sea surface temperature was around 0.5 before the Middle Pleistocene transition but was 1 thereafter. We subtract our ΔMOT reconstruction from the global δ18O record to derive the δ18O of seawater. Finally, we develop a theoretical understanding of why the ratio of ΔMOT / ΔGMSST changed over the Plio-Pleistocene.

Quantified ice-nucleating ability of AgI-containing seeding particles in natural clouds

We analyzed the ability of silver iodide particles (a commonly used cloud-seeding agent) to form ice crystals in naturally occurring liquid clouds at −5 to −8 °C and found that only ≈ 0.1 %−1 % of particles nucleate ice, with a negative dependence on temperature. By contextualizing our results with previous laboratory studies, we help to bridge the gap between laboratory and field experiments, which also helps to inform future cloud-seeding projects.

Calcium is associated with specific soil organic carbon decomposition products

SOIL
DOI 10.5194/soil-11-381-2025
20 May 2025

This study shows that calcium (Ca) preserves soil organic carbon (SOC) in acidic soils, challenging beliefs that their interactions were limited to near-neutral or alkaline soils. Using spectromicroscopy, we found that Ca was co-located with a specific fraction of carbon, rich in aromatic and phenolic groups. This association was disrupted when Ca was removed but was reformed during decomposition with added Ca. Overall, this suggests that Ca amendments could enhance SOC stability.