Herausforderung Klimawandel – Kommunikation und Wissenstransfer zwischen Fakten und gesellschaftlicher Handlungsnotwendigkeit

Renate Treffeisen und Klaus Grosfeld zeigen in ihren Beitrag, vor welchen Herausforderungen es beim Thema „Kimawandel“ aus dem Blickwinkel der Wissenschaftskommunikation geht. Sie appellieren zunächst dafür, statt von „Klimawandel" von „Klimakrise“ zu sprechen, damit der Blick auf Ursache, Dringlichkeit und den politischen Charakter des Problems in den Vordergrund tritt. Die Fridays4Future- und Scientists4Future-Bewegungen stünden dabei für ein Bottom-Up-Agenda-Setting, das Akteure zu Interaktion und Dialogbereitschaft auffordere. Treffeisen und Grosfeld erläutern daraufhin zwei Medienprojekte für erfolgreichen Wissenstransfer aus dem Forschungsverbund REKLIM

Paleo-ice sheet reconstructions constrained by GIA and geological data for use in climate models

Paleo-ice sheet reconstructions are complicated by large uncertainties, particularly since it is usually only possible to infer thickness from indirect means such as the response of glacial isostatic adjustment (GIA). GIA itself has large uncertainties with respect to the rheological structure of the Earth, and it is possible to get multiple possible best fitting ice sheet configurations using different Earth models. Usually the best geological constraints for paleo-ice sheets are ice margin location, via dating methods and geomorphological features. Using the program ICESHEET (Gowan et al 2016), it is possible to exploit this knowledge and create glaciologically consistent ice sheet reconstructions for use in GIA modeling. We demonstrate this by applying them to the North American Laurentide and Innuitian ice sheets, and show that it is possible to have an ice sheet that has a much lower profile than other GIA constrained reconstructions such as ICE-6G, GLAC-1 and ANU. A lower profile ice sheet has profound implications for past climate reconstructions, including radically different atmospheric and Atlantic Ocean circulation at the Last Glacial Maximum. Such a reconstruction is better able to fit geological constraints in the near field, but are at odds with global sea level reconstructions that require much larger ice volume. We discuss possible solutions to this issue. Another benefit of ICESHEET is that it does not require climatic information, since the ice thickness is adjusted by changing a spatially and temporarily variable basal shear stress parameter. Using these reconstructions in climate models do not face the circularity of dynamic ice sheet models that require a climatic input that was often derived from a-priori ice sheet reconstructions

DriftStories aus der zentralen Arktis - Ein Jahr, eine Scholle - Meereisforschung extrem

Einen Winter lang auf einer Eisscholle im Arktischen Ozean zu forschen, blieb für die meisten Meereisspezialisten bisher ein Traum. Zu aufwendig wäre die Expedition, zu unberechenbar das polare Wetter, hieß es immer. Im September 2019 aber begann, was vorher als unmöglich galt. Im Rahmen der internationalen MOSAiC-Expedition ließ sich der deutsche Forschungseisbrecher Polarstern für ein Jahr im Meereis der Arktis einfrieren und bot Polarforschenden aus 20 Nationen die Chance ihres Lebens. In einem Camp auf dem Eis in der zentralen Arktis untersuchten sie rund um die Uhr das Meereis, den Ozean, die Atmosphäre und das Leben im Meer. Sie wurden Zeugen einer gigantischen Transformation des Nordpolargebietes, deren erster Verlierer vermutlich das Meereis sein wird

Paleo-ice sheet reconstructions constrained by glacial isostatic adjustment and geological data

Paleo-ice sheet reconstructions are complicated by large uncertainties, particularly since it is usually only possible to infer thickness from indirect means such as the response of glacial isostatic adjustment (GIA). Recently, there has been increased attention to refining the chronology of ice sheet margins of paleo-ice sheets, and changes in relative sea level in formerly glaciated regions. Using this information, it is possible to infer the configuration of the ice sheets through time. Using the program ICESHEET (Gowan et al 2016), we reconstruct past ice sheets using a simple, though glaciologically plausible ice sheet model. The ice sheet volume is reconstructed by adjusting the basal shear stress at discrete time intervals in the region of interest until the modelled sea level is consistent with the sea level indicators. We demonstrate this technique by applying it to the Innuitian Ice Sheet. We also show the utility of the models for use in paleo-geographic reconstructions, as well as usage in paleo-climate simulations

September Arctic sea ice minimum prediction — a skillful new statistical approach

Sea ice in both polar regions is an important indicator of the expression of global climate change and its polar amplification. Consequently, broad interest exists on sea ice coverage, variability and long-term change. However, its predictability is complex and it depends strongly on different atmospheric and oceanic parameters. In order to provide insights into the potential development of a monthly/seasonal signal of sea ice evolution, we applied a robust statistical model based on different oceanic and atmospheric parameters to calculate an estimate of the September sea ice extent (SSIE) on a monthly timescale. Although previous statistical attempts of monthly/seasonal SSIE forecasts show a relatively reduced skill, when the trend is removed, we show here that the September sea ice extent has a high predictive skill, up to 4 months ahead, based on previous months’ oceanic and atmospheric conditions. Our statistical model skillfully captures the interannual variability of the SSIE and could provide a valuable tool for identifying relevant regions and oceanic and atmospheric parameters that are important for the sea ice development in the Arctic and for detecting sensitive/critical regions in global coupled climate models with a focus on sea ice formation

Oldest Ice in Antarctica – the 3d continental ice sheet modelling perspective.

The ongoing quest to find the oldest continuous ice core in Antarctica draws on the expertise of multiple disciplines. Here we present our efforts to inform on the location of potential future drilling sites by 3d continental ice sheet modelling. We present the results of an ensemble of ice sheet model simulations spanning the last 2 million years utilizing a variety of different model setups and boundary conditions including new radar derived bedrock elevation. In our analysis we focus on the physical properties and ice dynamics around the major drill sites such as Dome Fuji and Dome C and discuss the effects of the ice sheets history on the present day flow regime. By using a continental setup and applying a transient forcing created from paleo climate modelling studies and ice core data we are able to take a holistic view of Antarctic Ice Sheet dynamics and its impact on the vertical stratigraphy around the East Antarctic ice domes