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Changes in Arctic sea ice thickness are the result of complex interactions of the dynamic and variable ice cover with atmosphere and ocean. The availability of satellite-based estimates of Arctic-wide sea ice thickness changes is limited to the winter months. However, in light of recent model predictions of a nearly ice-free Arctic in summer and to understand the role of sea ice for the causes and consequences of a warming climate, long-term and large-scale sea ice thickness and surface observations during the melt season are more important than ever. The AWI airborne sea ice survey program ‘IceBird Summer’ aims to close this gap by conducting regular measurements over sea ice in summer in key regions of the Arctic Ocean. The survey program comprises and continues all airborne ice thickness measurements obtained since 2001 in the central Arctic, Fram Strait and the last ice area. The objective is to ensure the long-term availability of a unique data record of direct sea ice thickness and surface state observations (deliverable of AWI research program POFIV, Topic 2.1: Warming Climates). Sea ice thickness measurements are obtained with a tethered electromagnetic sensor, the AEM-Bird. Jointly with the ice thickness measurements, optical and laser systems are operated to derive sea ice surface models and melt pond distribution.

Climate change has led to an increase in permafrost warming and thaw at global scale. Land surface change associated with permafrost thaw include the acceleration of Arctic coastal erosion, increased thaw slumping in hillslope regions, the drainage and formation of lakes, as well as an intensification of disturbances on land, such as forest fires and droughts. Thermo-erosion threatens infrastructure and leads to gullying, slumping, and even landslides. Arctic communities living on frozen ground are strongly affected by these processes and are increasingly forced to adapt their livelihoods. In some areas, the relocation of settlements has become the last resort and is already actively planned for several communities in Alaska. Remote sensing analyses can be applied to detect and map permafrost disturbances at high spatial resolution across large regions to quantify landscape change, hydrological dynamics, and permafrost vulnerability. In the ERC PETA-CARB, ESA CCI Permafrost, and NSF Permafrost Discovery Gateway projects, a pan-arctic time series covering twenty years was produced using Landsat TM, ETM+, and OLI imagery. Following good scientific practice, this data is published via a digital data library and also available through a cloud-based analysis platform to facilitate re-use by other scientists. However, the data is not readily designed and presented to be interpreted by non-scientists and non-experts. In order to make the scientific findings more easily accessible, within the EU Arctic PASSION project we designed a tailored web-based portal specifically targeting non-scientific user communities, stakeholders, and rightsholders as part of the projects Permafrost Pilot Service. With the new portal, the Arctic Landscape EXplorer (ALEX), we provide interactive maps for recent information on land surface changes, hot spots of disturbances, and potential areas of active permafrost thaw and erosion. While focusing on the local to regional scale relevant for private users, as well as local, regional, and state-level decision makers, exploring the data up to the pan-arctic scale may open new avenues for understanding permafrost change for the general public. Recent consultations with local representatives and stakeholders from Alaska aimed to ensure that their actual information needs are met. Having received positive feedback and strong interest in the tool encouraged us to continue our work.

Calving of iceberg at ice shelves and floating glacier tongues is a poorly understood process, hence a physically motivated calving law is not yet existing. The demands on developing appropriate models for calving is large, as calving rates are needed for large scale ice sheet models that simulate the evolution of ice sheets. Here, we present a new approach for simulating fracture in ice. Our model is based on a finite strain theory for a viscoelastic Maxwell material, as the large simulation time leads to high strains. The fracturing process is simulated using a fracture phase field model that takes into account the elastic strain energy. We conduct simulations for a typical calving front geometry, with ice rises governing the formation of cracks. To represent the stress state adequately, we first conduct a spin-up to allow the viscous contribution to develop before the fracture phase field is computed. The analysis comprises the assessment of the crack path in comparison to observations, the influence of the spin-up, as well as elastic versus viscous strain contributions based on Hencky strain. Additionally, an estimate of released energy based on high resolution optical imagery of a Greenlandic calving front is presented.

In Sibirien wüteten in den letzten Jahren große Waldbrände. Neben der Bedrohung, die sie für menschliche Aktivitäten und Infrastruktur darstellen, könnten sie bei zunehmender Intensität und Frequenz auch eine einzigartige, von Permafrost geprägte Landschaft nachhaltig destabilisieren. Um mögliche Wechselwirkungen zwischen zunehmender Waldbrandaktivität und Waldstruktur auf langen Zeitskalen zu verstehen, werfen paläoökologisch Forschende einen Blick unter Wasser: In über lange Zeit abgelagerten Seesedimenten geben Verbrennungsprodukte Einblick in Waldbrandaktivitäten längst vergangener Zeiten.