Climate Research

Convective events, characterized by extreme precipitation, wind, lightning, and hail, consistently account for a significant portion of insured natural hazard damages, particularly affecting the agricultural, vehicle, and building sectors. In recent years, record-breaking hailstone sizes (up to 19 cm in Europe), substantial damage costs (e.g., 2021 in Switzerland), and prolonged, intense convective storms have been observed. The increase in temperatures due to global warming enhances the air's saturation vapor pressure, thereby intensifying convective processes through moisture supply and increased latent heat release. Many of the most intense convective events in Europe occur around the Alps, where large-scale atmospheric flow is significantly influenced by the complex topography of mountain ridges and valleys and interacts with regional to-local processes. Recent climatologies of hail and lightning indicate distinct hotspots of convective activity around the Alps. However, a comprehensive analysis of these hotspots, their spatio-temporal variability, and the underlying processes has not yet been conducted across multiple Alpine countries and convective hazards. The objective of CROSCEA is to systematically classify and characterize convective hotspots in the greater Alpine region. Subsequently, the regional-to-local processes driving increased convection will be analyzed in greater depth using high-resolution observational and model data. CROSCEA is associated with the European-scale TIM field campaign initiative (Thunderstorm Intensification from Mountains to Plains) spearheaded by the European Severe Storms Laboratory ESSL and is committed to contributing its findings to advance the overarching goals of TIM.

Schröer K, Jentsch H
Email: katharina.schroeer@geographie.uni-freiburg.de

Hail is one of the hazards associated with extreme convective events. It is one of the most expensive atmospheric hazards, and recent events have demonstrated this repeatedly with costly damage to vehicles, buildings, and agriculture. Hail is still one of the biggest challenges in forecasting, which is mainly due to the insufficient amount and quality of available data, together with the short spatio-temporal process scales. HAIPI aims to improve this situation integrating novel data sources to develop a product that estimates expected hail stone sizes through state-of-the-art machine learning algorithms. The focus is on crowd-sourced hail reports from the DWD WarnWetter-App as well as new dual-pol radar products, and existing products used in the DWD seamless forecast chain, e.g. KONRAD3D. As a first step, a routine for plausibility testing and quality control for the crowd-sourced data will be developed. The radar products will then be systematically evaluated, and uncertainties quantified. Using comparative machine learning analysis, an approach will be developed to predict expected hail stone sizes based on preprocessed input data. If proven skilful, a hail climatology for Germany will be derived from the resulting data product and the potential for impact assessments be evaluated. The outcomes will significantly advance the systematic observation and thus the prediction and warning of hail.

Schröer K
Email: katharina.schroeer@geographie.uni-freiburg.de

DWD EMF (extramurale Forschung)

The Upper Rhine region is particularly affected by the impacts of climate change. Heat waves and droughts, sultriness, tropical nights, but also floods and storms as well as poor air quality have an impact on people and the environment and especially also on small and medium-sized enterprises as well as the involved actors in their daily work. In the transnational research project Clim'Ability Care, several research institutions are working on how to deal with the challenges of climate change. Here it is possible to build on the findings of the previous projects Clim'Ability and Clim'Ability Design. In the new project phase Clim'Ability Care, the focus is on promoting and deriving a new climate-resilient corporate culture. The central question here is how to integrate the dimensions of warning, mitigation, adaptation and care. The specific objectives are to: (1) Selecting sites that are particularly sensitive to climate change due to their climatic and socioeconomic makeup (2) Updating and expanding the toolbox "Clim'Ability", in which climatic stressors and the resulting affectedness, but also adaptation strategies are available online (3) Promotion of a new corporate culture throughout the Upper Rhine region through "learning situations“ (4) Institutionalization through the creation of a new cross-border corporate and risk culture (5) Communication, dissemination and visibility of the project The collaboration between regional universities, public institutions and SMEs promotes synergies between different local, disciplinary and economic cultures. In parallel, the project explores the institutional and economic models and concepts with regard to the sustainability of territorial climate services in the Southern Upper Rhine region.

Gruner S

EU-INTERREG VI

Human influence has long interfered with natural floodplain evolution. While the indirect effects of deforestation on sediment transport and floodplain dynamics have been extensively researched, the socio-ecological processes and feedback mechanisms that determine how fluvial systems evolve along trajectories and path dependencies have only recently entered the scientific debate. We use the concept of a fluvio-social metabolism to illustrate these complex interdependencies between anthropogenic and natural processes that define how natural river systems transitioned into a fluvial anthroposphere. The aim of the project is to decipher the fluvio-social metabolism along path-dependencies and trajectories and to understand system dynamics of the fluvial anthroposphere in the Upper Rhine area. We focus on three specific aspects and their mutual interdependencies: socio-political systems, climate dynamics, and legacy sediments, integrating social and environmental archives as well as detailed laboratory and geostatistical analysis. By combining quantitative, semi-quantitative and qualitative methods we combine social and natural sciences. We seek to determine integrating indicators for the transition from natural floodplains to a fluvial anthroposphere on multiple spatio-temporal scales. Our research analyses the period from medieval times until the onset of the industrial revolution in the region around 1850 with focus on suspected transition periods. We hypothesise that in this fluvio-social system, specific socio-natural and political constellations, including territorial shifts, economical exploitation, institutions, conflicts, climatic variability and extremes, as well as riverine floods, determined path dependencies and trajectories of fluvial landscape evolution that found their expression in the floodplain record as legacy sediments. We follow a multidisciplinary approach that integrates the expertise from different disciplines, combining historic, climatic, and geomorphologic expertise. In three interlinking work packages, we investigate how 1) actors, socio-political constellations and institutions influenced floodplain development, 2) regional climate variability and extreme events impacted socio-ecological processes, and 3) natural and societal dynamics found their expression in the floodplain sedimentary record. Synthesising these various strands of social, climatic and geomorphologic results, we ultimately aim to integrate our insights into deciphering the fluvio-social metabolism. Finally, we evaluate to which degree our results can contribute to model this dynamic fluvio-social metabolism empirically, numerically and multivariate-statistically.

Blöthe J
Phone: 203-9224
Email: jan.bloethe@geographie.uni-freiburg.de

DFG

Socio-economic impacts of weather phenomena in a changing climate are a concern for government agencies, industry and the public, on time scales from hours (warnings) to decades (adaptation, long-term strategic planning). This project focuses on thunderstorm-related severe weather, in particular hail, one of the main weather-related damage drivers in Central Europe for agricultural crops and infrastructure, and related impacts today and in future. For further information see https://c2sm.ethz.ch/research/scclim.html.

SNF (Swiss National Science Foundation), Funding Scheme: Sinergia Grant

High-mountain environments are highly sensitive towards a warming climate, which is dramatically reflected by the shrinkage of alpine glaciers. With more and more glaciers disappearing, attention has moved towards the hydrological importance of ice stored in the periglacial environment, projected to exceed glacier ice volume in the European Alps by the mid-21st century. However, surprisingly little is known about the current state of the ice stored in the periglacial zones of alpine landscapes. Our project aims to disentangle the contribution of active layer and permafrost body to the summer runoff from the upper Kaiserberg catchment in the Austrian Alps. To achieve this goal, we combine repeated electrical resistivity tomography (ERT) surveys on the Kaiserberg rock glacier with continuous discharge measurements from two hydrological stations that we installed in the basin. We further collect water samples over the course of the summer that are analysed for δ18O and δ2H isotopes and the radio nuclide 129I , that allow us to differentiate thawing permafrost from active-layer or precipitation derived discharge.

Dr. Hohmann Förderung der Gesellschaft für Erdkunde zu Köln; Hanna Bremer Stiftung