Internal tides off the Amazon shelf in the western tropical Atlantic: analysis of SWOT Cal/Val mission data Ocean Science DOI 10.5194/os-21-325-2025 4 February 2025 This study focuses on the internal tides (ITs) off the Amazon shelf in the tropical Atlantic. It is based on 2 km horizontally gridded observations along the swaths of SWOT (Surface Water and Ocean Topography) track 20 during the calibration/validation phase (Cal/Val, 1 d orbit) from late March to early July 2023. We evaluate the amplitude of M2, N2, and S2 frequencies and use the M2 atlas as an internal tide correction model for SWOT observations. Internal tide amplitudes (models or atlases) are first derived by harmonic analysis of the SWOT sea level anomaly (SLA). The estimation is improved by performing a principal component analysis before the harmonic analysis. The results compare very well with the high-resolution empirical tide (HRET) internal tide model, the reference product for internal tide corrections in altimetry observations. The coherent mode 1 and mode 2 M2 can be distinguished in the internal tide model derived from SWOT, while the higher modes with their strong SLA signature are seen mostly in the incoherent part. In comparison to HRET, the correction of SWOT observations with SWOT-based atlases may be more relevant for this track. Read more
The alongshore tilt of mean dynamic topography and its implications for model validation and ocean monitoring Ocean Science DOI 10.5194/os-21-181-2025 31 January 2025 Mean dynamic topography (MDT) describes variations in the mean sea surface height above a reference surface called a geoid. We show that MDT predicted by a regional ocean model, including a significant tilt of several centimeters along the coast of Nova Scotia, is in good agreement with estimates based on sea level observations. We demonstrate that this alongshore tilt of MDT can provide a direct estimate of the average alongshore current and also of the area-integrated nearshore circulation. Read more
Assessment framework to predict sensitivity of marine calcifiers to ocean alkalinity enhancement – identification of biological thresholds and importance of precautionary principle Biogeosciences DOI 10.5194/bg-22-473-2025 31 January 2025 The environmental impacts of ocean alkalinity enhancement (OAE) are unknown. Our synthesis, based on 68 collected studies with 84 unique species, shows that 35 % of species respond positively, 26 % respond negatively, and 39 % show a neutral response to alkalinity addition. Biological thresholds were found from 50 to 500 µmol kg−1 NaOH addition. A precautionary approach is warranted to avoid potential risks, while current regulatory framework needs improvements to assure safe biological limits. Read more
Blending 2D topography images from the Surface Water and Ocean Topography (SWOT) mission into the altimeter constellation with the Level-3 multi-mission Data Unification and Altimeter Combination System (DUACS) Ocean Science DOI 10.5194/os-21-283-2025 31 January 2025 The Surface Water and Ocean Topography (SWOT) mission delivers unprecedented swath-altimetry products. In this paper, we describe how we extended the Level-3 algorithms to handle SWOT’s unique swath-altimeter data. We also illustrate and discuss the benefits, relevance, and limitations of Level-3 swath-altimeter products for various research domains. Read more
Modelling current and future forest fire susceptibility in north-eastern Germany Natural Hazards and Earth System Sciences DOI 10.5194/nhess-25-383-2025 30 January 2025 In this study we applied a random forest machine learning algorithm to model current and future forest fire susceptibility (FFS) in north-eastern Germany using anthropogenic, climatic, topographic, soil, and vegetation variables. Model accuracy ranged between 69 % and 71 %, showing moderately high model reliability for predicting FFS. The model results underline the importance of anthropogenic and vegetation parameters. This study will support regional forest fire prevention and management. Read more
Present-day mass loss rates are a precursor for West Antarctic Ice Sheet collapse The Cryosphere DOI 10.5194/tc-19-283-2025 29 January 2025 In this study, we present an improved way of representing ice thickness change rates in an ice sheet model. We apply this method using two ice sheet models of the Antarctic Ice Sheet. We found that the two largest outlet glaciers on the Antarctic Ice Sheet, Thwaites Glacier and Pine Island Glacier, will collapse without further warming on a timescale of centuries. This would cause a sea level rise of about 1.2 m globally. Read more
Opinion: Understanding the impacts of agriculture and food systems on atmospheric chemistry is instrumental to achieving multiple Sustainable Development Goals Atmospheric Chemistry and Physics DOI 10.5194/acp-25-923-2025 28 January 2025 We discuss our current understanding of and knowledge gaps in how agriculture and food systems affect air quality and how agricultural emissions can be mitigated. We argue that scientists need to address these gaps, especially as the importance of fossil fuel emissions is fading. This will help guide food-system transformation in economically viable, socially inclusive, and environmentally responsible ways and is essential to help society achieve sustainable development. Read more
A methodology to compile multi-hazard interrelationships in a data-scarce setting: an application to the Kathmandu Valley, Nepal Natural Hazards and Earth System Sciences DOI 10.5194/nhess-25-353-2025 27 January 2025 We present a methodology to compile single hazards and multi-hazard interrelationships in data-scarce urban settings, which we apply to the Kathmandu Valley, Nepal. Using blended sources, we collate evidence of 21 single natural hazard types and 83 multi-hazard interrelationships that could impact the Kathmandu Valley. We supplement these exemplars with multi-hazard scenarios developed by practitioner stakeholders, emphasising the need for inclusive disaster preparedness and response approaches. Read more
Spatial identification of regions exposed to multi-hazards at the pan-European level Natural Hazards and Earth System Sciences DOI 10.5194/nhess-25-287-2025 24 January 2025 This is the first study that uses spatial patterns (clusters/hotspots) and meta-analysis in order to identify the regions at a European level at risk of multi-hazards. The findings point out the socioeconomic dimension as a determining factor in the potential risk of multi-hazards. The outcome provides valuable input for the disaster risk management policy support and will assist national authorities on the implementation of a multi-hazard approach in national risk assessment preparation. Read more
Impacts from cascading multi-hazards using hypergraphs: a case study from the 2015 Gorkha earthquake in Nepal Natural Hazards and Earth System Sciences DOI 10.5194/nhess-25-267-2025 22 January 2025 Natural hazards like earthquakes often trigger other disasters, such as landslides, creating complex chains of impacts. We developed a risk model using a mathematical approach called hypergraphs to efficiently measure the impact of interconnected hazards. We showed that it can predict broad patterns of damage to buildings and roads from the 2015 Nepal earthquake. The model’s efficiency allows it to generate multiple disaster scenarios, even at a national scale, to support preparedness plans. Read more
