In 2017, researchers retrieved an eleven-metre-long sediment core from Lake Vangsvatnet in Voss. The core reveals 8,000 years of flood history in the community, west in Norway.

Abstract Glacial inception is commonly interpreted as a response to declining summer insolation, which reduces ablation and allows perennial snow to accumulate. How the controls on ice-sheet growth evolve after this initial phase, however, is less well understood. Here, we analyze a transient simulation of the last glacial inception from 127 to 65 ka using the AWI Earth System Model (AWI-ESM) coupled to the Parallel Ice Sheet Model (PISM) for the Northern Hemisphere domain. Our results show two stages of Laurentide Ice Sheet (LIS) growth. During the early phase (127–115 ka), glaciation is mainly associated with reduced summer melt and follows the southward migration of the summer 0 °C isotherm. After approximately 115 ka, this relationship changes and the ice sheet margin continues to advance into regions with negative surface mass balance. A decomposition of changes in local ice thickness indicates that dynamic mass redistribution from the interior to the margin supports this advance. Changes in LIS surface elevation are associated with changes in regional moisture transport and an increasing fraction of precipitation falling as snow over parts of the ice sheet help maintain a positive surface mass balance in the interior. Our simulation indicates a transition from early, climate-limited glaciation to dynamically supported growth, in which local climate conditions no longer determine ice-sheet advance. Although the timing and magnitude of this transition depend on the experimental setup, our results show how an evolving ice sheet can shift the relative roles of melt, accumulation, and ice dynamics during glacial inception. Speaker information Lars Ackermann is a postdoctoral researcher in the Paleoclimate Dynamics section at the Alfred Wegener Institute (AWI). He received his PhD from the University of Bremen in 2023 and has been part of the PalMod project (Paleo Modelling) since 2020. His research focuses on long-term climate–ice sheet interactions, particularly the role of the Greenland Ice Sheet and icebergs in past and future climate change. Using coupled climate–ice sheet modelling, he investigates ice sheet evolution and its impacts on ocean circulation and the wider climate system over centennial to millennial timescales. Join Zoom Meeting https://uib.zoom.us/j/68304284910?pwd=2IgsDMWHuJlQw3XFHSTo3OoGBsRrhz.1 Meeting ID: 683 0428 4910 Password: 7pwZK4mG

Abstract Moist convection is organized across a wide range of scales, yet many of the processes that modulate it are difficult to quantify from an Eulerian perspective. In this talk, I will show how the coupling between a cloud-resolving model and a Lagrangian particle model can be used to address this limitation. Lagrangian particles are particularly useful because they can encode the history of air parcels. I will first discuss what this approach reveals about the dynamics of precipitation-driven downdrafts and cold pools--arguably one of the least understood components of moist convection--and about the mechanisms by which cold pools can trigger and organize new convective cells. I will then show how this framework can be extended to stable water isotopes. Because each particle carries its own isotopic composition, changes along its trajectory can be attributed to individual processes, such as rain evaporation, equilibration, mixing, and surface fluxes. This reveals, for example, that surface latent heat fluxes, rather than entrainment, control the isotopic composition of cold pools, and it provides a process-based foundation for interpreting isotope observations of convection. Finally, I will briefly discuss how this framework might be applied to marine cold-air outbreaks over the North Atlantic and Nordic Seas. Speaker information Giuseppe Torri is an Associate Professor of Atmospheric Sciences at the University of Hawaiʻi at Mānoa. His research focuses on the dynamics and organization of moist convection, with particular interests in precipitating convection, its interaction with larger-scale circulations and, more recently, the dynamics of extreme weather. Much of this work relies on the application of Lagrangian particle models and water isotopes to obtain a process-based understanding of atmospheric phenomena that are otherwise hard to quantify. He also studies island hydroclimates across a range of spatial and temporal scales. He trained as a theoretical physicist, receiving his PhD from Imperial College London, before moving into atmospheric science as a postdoctoral fellow at Harvard University.