TY - JOUR
A1 - Ehrig, Lukas
A1 - Wagner, Ann-Christin
A1 - Wolter, Heike
A1 - Correll, Christoph U.
A1 - Geisel, Olga
A1 - Konigorski, Stefan
T1 - FASDetect as a machine learning-based screening app for FASD in youth with ADHD
JF - npj Digital Medicine
N2 - Fetal alcohol-spectrum disorder (FASD) is underdiagnosed and often misdiagnosed as attention-deficit/hyperactivity disorder (ADHD). Here, we develop a screening tool for FASD in youth with ADHD symptoms. To develop the prediction model, medical record data from a German University outpatient unit are assessed including 275 patients aged 0-19 years old with FASD with or without ADHD and 170 patients with ADHD without FASD aged 0-19 years old. We train 6 machine learning models based on 13 selected variables and evaluate their performance. Random forest models yield the best prediction models with a cross-validated AUC of 0.92 (95% confidence interval [0.84, 0.99]). Follow-up analyses indicate that a random forest model with 6 variables - body length and head circumference at birth, IQ, socially intrusive behaviour, poor memory and sleep disturbance - yields equivalent predictive accuracy. We implement the prediction model in a web-based app called FASDetect - a user-friendly, clinically scalable FASD risk calculator that is freely available at https://fasdetect.dhc-lab.hpi.de.
KW - Medical research
KW - Psychiatric disorders
Y1 - 2023
U6 - https://doi.org/10.1038/s41746-023-00864-1
SN - 2398-6352
VL - 6
IS - 1
PB - Macmillan Publishers Limited
CY - Basingstoke
ER -
TY - JOUR
A1 - Slosarek, Tamara
A1 - Ibing, Susanne
A1 - Schormair, Barbara
A1 - Heyne, Henrike
A1 - Böttinger, Erwin
A1 - Andlauer, Till
A1 - Schurmann, Claudia
T1 - Implementation and evaluation of personal genetic testing as part of genomics analysis courses in German universities
JF - BMC Medical Genomics
N2 - Purpose
Due to the increasing application of genome analysis and interpretation in medical disciplines, professionals require adequate education. Here, we present the implementation of personal genotyping as an educational tool in two genomics courses targeting Digital Health students at the Hasso Plattner Institute (HPI) and medical students at the Technical University of Munich (TUM).
Methods
We compared and evaluated the courses and the students ' perceptions on the course setup using questionnaires.
Results
During the course, students changed their attitudes towards genotyping (HPI: 79% [15 of 19], TUM: 47% [25 of 53]). Predominantly, students became more critical of personal genotyping (HPI: 73% [11 of 15], TUM: 72% [18 of 25]) and most students stated that genetic analyses should not be allowed without genetic counseling (HPI: 79% [15 of 19], TUM: 70% [37 of 53]). Students found the personal genotyping component useful (HPI: 89% [17 of 19], TUM: 92% [49 of 53]) and recommended its inclusion in future courses (HPI: 95% [18 of 19], TUM: 98% [52 of 53]).
Conclusion
Students perceived the personal genotyping component as valuable in the described genomics courses. The implementation described here can serve as an example for future courses in Europe.
KW - Genomics education
KW - Personal genotyping
KW - Personalized medicine
Y1 - 2023
U6 - https://doi.org/10.1186/s12920-023-01503-0
SN - 1755-8794
VL - 16
IS - 1
PB - BMC
CY - London
ER -
TY - CHAP
A1 - Rieskamp, Jonas
A1 - Mirbabaie, Milad
A1 - Hofeditz, Lennart
A1 - Vischedyk, Justin
T1 - Conversational agents and their influence on the well-being of cliniciansclinicians
T2 - ACIS 2023 proceedings
N2 - An increasing number of clinicians (i.e., nurses and physicians) suffer from mental health-related issues like depression and burnout. These, in turn, stress communication, collaboration, and decision- making—areas in which Conversational Agents (CAs) have shown to be useful. Thus, in this work, we followed a mixed-method approach and systematically analysed the literature on factors affecting the well-being of clinicians and CAs’ potential to improve said well-being by relieving support in communication, collaboration, and decision-making in hospitals. In this respect, we are guided by Brigham et al. (2018)’s model of factors influencing well-being. Based on an initial number of 840 articles, we further analysed 52 papers in more detail and identified the influences of CAs’ fields of application on external and individual factors affecting clinicians’ well-being. As our second method, we will conduct interviews with clinicians and experts on CAs to verify and extend these influencing factors.
KW - conversational agents
KW - well-being
KW - mental health
KW - hospitals
KW - clinicians
Y1 - 2023
UR - https://aisel.aisnet.org/acis2023/66
PB - Australasian Association for Information Systems
CY - Wellington
ER -
TY - JOUR
A1 - Seroussi, Helene
A1 - Nowicki, Sophie
A1 - Simon, Erika
A1 - Abe-Ouchi, Ayako
A1 - Albrecht, Torsten
A1 - Brondex, Julien
A1 - Cornford, Stephen
A1 - Dumas, Christophe
A1 - Gillet-Chaulet, Fabien
A1 - Goelzer, Heiko
A1 - Golledge, Nicholas R.
A1 - Gregory, Jonathan M.
A1 - Greve, Ralf
A1 - Hoffman, Matthew J.
A1 - Humbert, Angelika
A1 - Huybrechts, Philippe
A1 - Kleiner, Thomas
A1 - Larourl, Eric
A1 - Leguy, Gunter
A1 - Lipscomb, William H.
A1 - Lowry, Daniel
A1 - Mengel, Matthias
A1 - Morlighem, Mathieu
A1 - Pattyn, Frank
A1 - Payne, Anthony J.
A1 - Pollard, David
A1 - Price, Stephen F.
A1 - Quiquet, Aurelien
A1 - Reerink, Thomas J.
A1 - Reese, Ronja
A1 - Rodehacke, Christian B.
A1 - Schlegel, Nicole-Jeanne
A1 - Shepherd, Andrew
A1 - Sun, Sainan
A1 - Sutter, Johannes
A1 - Van Breedam, Jonas
A1 - van de Wal, Roderik S. W.
A1 - Winkelmann, Ricarda
A1 - Zhang, Tong
T1 - initMIP-Antarctica
BT - an ice sheet model initialization experiment of ISMIP6
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - Ice sheet numerical modeling is an important tool to estimate the dynamic contribution of the Antarctic ice sheet to sea level rise over the coming centuries. The influence of initial conditions on ice sheet model simulations, however, is still unclear. To better understand this influence, an initial state intercomparison exercise (initMIP) has been developed to compare, evaluate, and improve initialization procedures and estimate their impact on century-scale simulations. initMlP is the first set of experiments of the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6), which is the primary Coupled Model Intercomparison Project Phase 6 (CMIP6) activity focusing on the Greenland and Antarctic ice sheets. Following initMlP-Greenland, initMlP-Antarctica has been designed to explore uncertainties associated with model initialization and spin-up and to evaluate the impact of changes in external forcings. Starting from the state of the Antarctic ice sheet at the end of the initialization procedure, three forward experiments are each run for 100 years: a control run, a run with a surface mass balance anomaly, and a run with a basal melting anomaly beneath floating ice. This study presents the results of initMlP-Antarctica from 25 simulations performed by 16 international modeling groups. The submitted results use different initial conditions and initialization methods, as well as ice flow model parameters and reference external forcings. We find a good agreement among model responses to the surface mass balance anomaly but large variations in responses to the basal melting anomaly. These variations can be attributed to differences in the extent of ice shelves and their upstream tributaries, the numerical treatment of grounding line, and the initial ocean conditions applied, suggesting that ongoing efforts to better represent ice shelves in continental-scale models should continue.
Y1 - 2019
U6 - https://doi.org/10.5194/tc-13-1441-2019
SN - 1994-0416
SN - 1994-0424
VL - 13
IS - 5
SP - 1441
EP - 1471
PB - Copernicus
CY - Göttingen
ER -
TY - JOUR
A1 - Reese, Ronja
A1 - Albrecht, Torsten
A1 - Mengel, Matthias
A1 - Asay-Davis, Xylar
A1 - Winkelmann, Ricarda
T1 - Antarctic sub-shelf melt rates via PICO
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - Ocean-induced melting below ice shelves is one of the dominant drivers for mass loss from the Antarctic Ice Sheet at present. An appropriate representation of sub-shelf melt rates is therefore essential for model simulations of marine-based ice sheet evolution. Continental-scale ice sheet models often rely on simple melt-parameterizations, in particular for long-term simulations, when fully coupled ice-ocean interaction becomes computationally too expensive. Such parameterizations can account for the influence of the local depth of the ice-shelf draft or its slope on melting. However, they do not capture the effect of ocean circulation underneath the ice shelf. Here we present the Potsdam Ice-shelf Cavity mOdel (PICO), which simulates the vertical overturning circulation in ice-shelf cavities and thus enables the computation of sub-shelf melt rates consistent with this circulation. PICO is based on an ocean box model that coarsely resolves ice shelf cavities and uses a boundary layer melt formulation. We implement it as a module of the Parallel Ice Sheet Model (PISM) and evaluate its performance under present-day conditions of the Southern Ocean. We identify a set of parameters that yield two-dimensional melt rate fields that qualitatively reproduce the typical pattern of comparably high melting near the grounding line and lower melting or refreezing towards the calving front. PICO captures the wide range of melt rates observed for Antarctic ice shelves, with an average of about 0.1 ma(-1) for cold sub-shelf cavities, for example, underneath Ross or Ronne ice shelves, to 16 ma(-1) for warm cavities such as in the Amundsen Sea region. This makes PICO a computationally feasible and more physical alternative to melt parameterizations purely based on ice draft geometry.
Y1 - 2018
U6 - https://doi.org/10.5194/tc-12-1969-2018
SN - 1994-0416
SN - 1994-0424
VL - 12
IS - 6
SP - 1969
EP - 1985
PB - Copernicus
CY - Göttingen
ER -
TY - JOUR
A1 - Reese, Ronja
A1 - Winkelmann, Ricarda
A1 - Gudmundsson, Gudmundur Hilmar
T1 - Grounding-line flux formula applied as a flux condition in numerical simulations fails for buttressed Antarctic ice streams
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - Currently, several large-scale ice-flow models impose a condition on ice flux across grounding lines using an analytically motivated parameterisation of grounding-line flux. It has been suggested that employing this analytical expression alleviates the need for highly resolved computational domains around grounding lines of marine ice sheets. While the analytical flux formula is expected to be accurate in an unbuttressed flow-line setting, its validity has hitherto not been assessed for complex and realistic geometries such as those of the Antarctic Ice Sheet. Here the accuracy of this analytical flux formula is tested against an optimised ice flow model that uses a highly resolved computational mesh around the Antarctic grounding lines. We find that when applied to the Antarctic Ice Sheet the analytical expression provides inaccurate estimates of ice fluxes for almost all grounding lines. Furthermore, in many instances direct application of the analytical formula gives rise to unphysical complex-valued ice fluxes. We conclude that grounding lines of the Antarctic Ice Sheet are, in general, too highly buttressed for the analytical parameterisation to be of practical value for the calculation of grounding-line fluxes.
Y1 - 2018
U6 - https://doi.org/10.5194/tc-12-3229-2018
SN - 1994-0416
SN - 1994-0424
VL - 12
IS - 10
SP - 3229
EP - 3242
PB - Copernicus
CY - Göttingen
ER -
TY - JOUR
A1 - Ciemer, Catrin
A1 - Rehm, Lars
A1 - Kurths, Jürgen
A1 - Donner, Reik Volker
A1 - Winkelmann, Ricarda
A1 - Boers, Niklas
T1 - An early-warning indicator for Amazon droughts exclusively based on tropical Atlantic sea surface temperatures
JF - Environmental Research Letters
N2 - Droughts in tropical South America have an imminent and severe impact on the Amazon rainforest and affect the livelihoods of millions of people. Extremely dry conditions in Amazonia have been previously linked to sea surface temperature (SST) anomalies in the adjacent tropical oceans. Although the sources and impacts of such droughts have been widely studied, establishing reliable multi-year lead statistical forecasts of their occurrence is still an ongoing challenge. Here, we further investigate the relationship between SST and rainfall anomalies using a complex network approach. We identify four ocean regions which exhibit the strongest overall SST correlations with central Amazon rainfall, including two particularly prominent regions in the northern and southern tropical Atlantic. Based on the time-dependent correlation between SST anomalies in these two regions alone, we establish a new early-warning method for droughts in the central Amazon basin and demonstrate its robustness in hindcasting past major drought events with lead-times up to 18 months.
KW - complex networks
KW - droughts
KW - prediction
KW - Amazon rainforest
Y1 - 2019
VL - 15
IS - 9
PB - IOP - Institute of Physics Publishing
CY - Bristol
ER -
TY - JOUR
A1 - Seroussi, Helene
A1 - Nowicki, Sophie
A1 - Payne, Antony J.
A1 - Goelzer, Heiko
A1 - Lipscomb, William H.
A1 - Abe-Ouchi, Ayako
A1 - Agosta, Cecile
A1 - Albrecht, Torsten
A1 - Asay-Davis, Xylar
A1 - Barthel, Alice
A1 - Calov, Reinhard
A1 - Cullather, Richard
A1 - Dumas, Christophe
A1 - Galton-Fenzi, Benjamin K.
A1 - Gladstone, Rupert
A1 - Golledge, Nicholas R.
A1 - Gregory, Jonathan M.
A1 - Greve, Ralf
A1 - Hattermann, Tore
A1 - Hoffman, Matthew J.
A1 - Humbert, Angelika
A1 - Huybrechts, Philippe
A1 - Jourdain, Nicolas C.
A1 - Kleiner, Thomas
A1 - Larour, Eric
A1 - Leguy, Gunter R.
A1 - Lowry, Daniel P.
A1 - Little, Chistopher M.
A1 - Morlighem, Mathieu
A1 - Pattyn, Frank
A1 - Pelle, Tyler
A1 - Price, Stephen F.
A1 - Quiquet, Aurelien
A1 - Reese, Ronja
A1 - Schlegel, Nicole-Jeanne
A1 - Shepherd, Andrew
A1 - Simon, Erika
A1 - Smith, Robin S.
A1 - Straneo, Fiammetta
A1 - Sun, Sainan
A1 - Trusel, Luke D.
A1 - Van Breedam, Jonas
A1 - van de Wal, Roderik S. W.
A1 - Winkelmann, Ricarda
A1 - Zhao, Chen
A1 - Zhang, Tong
A1 - Zwinger, Thomas
T1 - ISMIP6 Antarctica
BT - a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - Ice flow models of the Antarctic ice sheet are commonly used to simulate its future evolution in response to different climate scenarios and assess the mass loss that would contribute to future sea level rise. However, there is currently no consensus on estimates of the future mass balance of the ice sheet, primarily because of differences in the representation of physical processes, forcings employed and initial states of ice sheet models. This study presents results from ice flow model simulations from 13 international groups focusing on the evolution of the Antarctic ice sheet during the period 2015-2100 as part of the Ice Sheet Model Intercomparison for CMIP6 (ISMIP6). They are forced with outputs from a subset of models from the Coupled Model Intercomparison Project Phase 5 (CMIP5), representative of the spread in climate model results. Simulations of the Antarctic ice sheet contribution to sea level rise in response to increased warming during this period varies between 7:8 and 30.0 cm of sea level equivalent (SLE) under Representative Concentration Pathway (RCP) 8.5 scenario forcing. These numbers are relative to a control experiment with constant climate conditions and should therefore be added to the mass loss contribution under climate conditions similar to present-day conditions over the same period. The simulated evolution of the West Antarctic ice sheet varies widely among models, with an overall mass loss, up to 18.0 cm SLE, in response to changes in oceanic conditions. East Antarctica mass change varies between 6 :1 and 8.3 cm SLE in the simulations, with a significant increase in surface mass balance outweighing the increased ice discharge under most RCP 8.5 scenario forcings. The inclusion of ice shelf collapse, here assumed to be caused by large amounts of liquid water ponding at the surface of ice shelves, yields an additional simulated mass loss of 28mm compared to simulations without ice shelf collapse. The largest sources of uncertainty come from the climate forcing, the ocean-induced melt rates, the calibration of these melt rates based on oceanic conditions taken outside of ice shelf cavities and the ice sheet dynamic response to these oceanic changes. Results under RCP 2.6 scenario based on two CMIP5 climate models show an additional mass loss of 0 and 3 cm of SLE on average compared to simulations done under present-day conditions for the two CMIP5 forcings used and display limited mass gain in East Antarctica.
Y1 - 2020
U6 - https://doi.org/10.5194/tc-14-3033-2020
SN - 1994-0416
SN - 1994-0424
VL - 14
IS - 9
SP - 3033
EP - 3070
PB - Copernicus
CY - Göttingen
ER -
TY - JOUR
A1 - Reese, Ronja
A1 - Levermann, Anders
A1 - Albrecht, Torsten
A1 - Seroussi, Helene
A1 - Winkelmann, Ricarda
T1 - The role of history and strength of the oceanic forcing in sea level projections from Antarctica with the Parallel Ice Sheet Model
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - Mass loss from the Antarctic Ice Sheet constitutes the largest uncertainty in projections of future sea level rise. Ocean-driven melting underneath the floating ice shelves and subsequent acceleration of the inland ice streams are the major reasons for currently observed mass loss from Antarctica and are expected to become more important in the future. Here we show that for projections of future mass loss from the Antarctic Ice Sheet, it is essential (1) to better constrain the sensitivity of sub-shelf melt rates to ocean warming and (2) to include the historic trajectory of the ice sheet. In particular, we find that while the ice sheet response in simulations using the Parallel Ice Sheet Model is comparable to the median response of models in three Antarctic Ice Sheet Intercomparison projects - initMIP, LARMIP-2 and ISMIP6 - conducted with a range of ice sheet models, the projected 21st century sea level contribution differs significantly depending on these two factors. For the highest emission scenario RCP8.5, this leads to projected ice loss ranging from 1:4 to 4:0 cm of sea level equivalent in simulations in which ISMIP6 ocean forcing drives the PICO ocean box model where parameter tuning leads to a comparably low sub-shelf melt sensitivity and in which no surface forcing is applied. This is opposed to a likely range of 9:1 to 35:8 cm using the exact same initial setup, but emulated from the LARMIP-2 experiments with a higher melt sensitivity, even though both projects use forcing from climate models and melt rates are calibrated with previous oceanographic studies. Furthermore, using two initial states, one with a previous historic simulation from 1850 to 2014 and one starting from a steady state, we show that while differences between the ice sheet configurations in 2015 seem marginal at first sight, the historic simulation increases the susceptibility of the ice sheet to ocean warming, thereby increasing mass loss from 2015 to 2100 by 5% to 50 %. Hindcasting past ice sheet changes with numerical models would thus provide valuable tools to better constrain projections. Our results emphasize that the uncertainty that arises from the forcing is of the same order of magnitude as the ice dynamic response for future sea level projections.
Y1 - 2020
U6 - https://doi.org/10.5194/tc-14-3097-2020
SN - 1994-0416
SN - 1994-0424
VL - 14
IS - 9
SP - 3097
EP - 3110
PB - Copernicus
CY - Göttingen
ER -
TY - JOUR
A1 - Zeitz, Maria
A1 - Levermann, Anders
A1 - Winkelmann, Ricarda
T1 - Sensitivity of ice loss to uncertainty in flow law parameters in an idealized one-dimensional geometry
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - Acceleration of the flow of ice drives mass losses in both the Antarctic and the Greenland Ice Sheet. The projections of possible future sea-level rise rely on numerical ice-sheet models, which solve the physics of ice flow, melt, and calving. While major advancements have been made by the ice-sheet modeling community in addressing several of the related uncertainties, the flow law, which is at the center of most process-based ice-sheet models, is not in the focus of the current scientific debate. However, recent studies show that the flow law parameters are highly uncertain and might be different from the widely accepted standard values. Here, we use an idealized flow-line setup to investigate how these uncertainties in the flow law translate into uncertainties in flow-driven mass loss. In order to disentangle the effect of future warming on the ice flow from other effects, we perform a suite of experiments with the Parallel Ice Sheet Model (PISM), deliberately excluding changes in the surface mass balance. We find that changes in the flow parameters within the observed range can lead up to a doubling of the flow-driven mass loss within the first centuries of warming, compared to standard parameters. The spread of ice loss due to the uncertainty in flow parameters is on the same order of magnitude as the increase in mass loss due to surface warming. While this study focuses on an idealized flow-line geometry, it is likely that this uncertainty carries over to realistic three-dimensional simulations of Greenland and Antarctica.
Y1 - 2020
U6 - https://doi.org/10.5194/tc-14-3537-2020
SN - 1994-0416
SN - 1994-0424
VL - 14
IS - 10
SP - 3537
EP - 3550
PB - Copernicus
CY - Göttingen
ER -
TY - JOUR
A1 - Albrecht, Torsten
A1 - Winkelmann, Ricarda
A1 - Levermann, Anders
T1 - Glacial-cycle simulations of the Antarctic Ice Sheet with the Parallel Ice Sheet Model (PISM)
BT - Part 1: boundary conditions and climatic forcing
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - Simulations of the glacial-interglacial history of the Antarctic Ice Sheet provide insights into dynamic threshold behavior and estimates of the ice sheet's contributions to global sea-level changes for the past, present and future. However, boundary conditions are weakly constrained, in particular at the interface of the ice sheet and the bedrock. Also climatic forcing covering the last glacial cycles is uncertain, as it is based on sparse proxy data.
We use the Parallel Ice Sheet Model (PISM) to investigate the dynamic effects of different choices of input data, e.g., for modern basal heat flux or reconstructions of past changes of sea level and surface temperature. As computational resources are limited, glacial-cycle simulations are performed using a comparably coarse model grid of 16 km and various parameterizations, e.g., for basal sliding, iceberg calving, or for past variations in precipitation and ocean temperatures. In this study we evaluate the model's transient sensitivity to corresponding parameter choices and to different boundary conditions over the last two glacial cycles and provide estimates of involved uncertainties. We also discuss isolated and combined effects of climate and sea-level forcing. Hence, this study serves as a "cookbook" for the growing community of PISM users and paleo-ice sheet modelers in general.
For each of the different model uncertainties with regard to climatic forcing, ice and Earth dynamics, and basal processes, we select one representative model parameter that captures relevant uncertainties and motivates corresponding parameter ranges that bound the observed ice volume at present. The four selected parameters are systematically varied in a parameter ensemble analysis, which is described in a companion paper.
Y1 - 2020
U6 - https://doi.org/10.5194/tc-14-599-2020
SN - 1994-0416
SN - 1994-0424
VL - 14
IS - 2
SP - 599
EP - 632
PB - Copernicus
CY - Göttingen
ER -
TY - JOUR
A1 - Kreuzer, Moritz
A1 - Reese, Ronja
A1 - Huiskamp, Willem Nicholas
A1 - Petri, Stefan
A1 - Albrecht, Torsten
A1 - Feulner, Georg
A1 - Winkelmann, Ricarda
T1 - Coupling framework (1.0) for the PISM (1.1.4) ice sheet model and the MOMS (5.1.0) ocean model via the PICO ice shelf cavity model in an Antarctic domain
JF - Geoscientific model development : an interactive open access journal of the European Geosciences Union
N2 - The past and future evolution of the Antarctic Ice Sheet is largely controlled by interactions between the ocean and floating ice shelves. To investigate these interactions, coupled ocean and ice sheet model configurations are required. Previous modelling studies have mostly relied on high-resolution configurations, limiting these studies to individual glaciers or regions over short timescales of decades to a few centuries. We present a framework to couple the dynamic ice sheet model PISM (Parallel Ice Sheet Model) with the global ocean general circulation model MOM5 (Modular Ocean Model) via the ice shelf cavity model PICO (Pots-dam Ice-shelf Cavity mOdel). As ice shelf cavities are not resolved by MOM5 but are parameterized with the PICO box model, the framework allows the ice sheet and ocean components to be run at resolutions of 16 km and 3 degrees respectively. This approach makes the coupled configuration a useful tool for the analysis of interactions between the Antarctic Ice Sheet and the global ocean over time spans of the order of centuries to millennia. In this study, we describe the technical implementation of this coupling framework: sub-shelf melting in the ice sheet component is calculated by PICO from modelled ocean temperatures and salinities at the depth of the continental shelf, and, vice versa, the resulting mass and energy fluxes from melting at the ice-ocean interface are transferred to the ocean component. Mass and energy fluxes are shown to be conserved to machine precision across the considered component domains. The implementation is computationally efficient as it introduces only minimal overhead. Furthermore, the coupled model is evaluated in a 4000 year simulation under constant present-day climate forcing and is found to be stable with respect to the ocean and ice sheet spin-up states. The framework deals with heterogeneous spatial grid geometries, varying grid resolutions, and timescales between the ice and ocean component in a generic way; thus, it can be adopted to a wide range of model set-ups.
Y1 - 2021
U6 - https://doi.org/10.5194/gmd-14-3697-2021
SN - 1991-959X
SN - 1991-9603
VL - 14
IS - 6
SP - 3697
EP - 3714
PB - Copernicus
CY - Göttingen
ER -
TY - JOUR
A1 - Zeitz, Maria
A1 - Haacker, Jan M.
A1 - Donges, Jonathan
A1 - Albrecht, Torsten
A1 - Winkelmann, Ricarda
T1 - Dynamic regimes of the Greenland Ice Sheet emerging from interacting melt-elevation and glacial isostatic adjustment feedbacks
JF - Earth system dynamics
N2 - The stability of the Greenland Ice Sheet under global warming is governed by a number of dynamic processes and interacting feedback mechanisms in the ice sheet, atmosphere and solid Earth.
Here we study the long-term effects due to the interplay of the competing melt-elevation and glacial isostatic adjustment (GIA) feedbacks for different temperature step forcing experiments with a coupled ice-sheet and solid-Earth model.
Our model results show that for warming levels above 2 degrees C, Greenland could become essentially ice-free within several millennia, mainly as a result of surface melting and acceleration of ice flow. These ice losses are mitigated, however, in some cases with strong GIA feedback even promoting an incomplete recovery of the Greenland ice volume. We further explore the full-factorial parameter space determining the relative strengths of the two feedbacks: our findings suggest distinct dynamic regimes of the Greenland Ice Sheets on the route to destabilization under global warming - from incomplete recovery, via quasi-periodic oscillations in ice volume to ice-sheet collapse.
In the incomplete recovery regime, the initial ice loss due to warming is essentially reversed within 50 000 years, and the ice volume stabilizes at 61 %-93 % of the present-day volume. For certain combinations of temperature increase, atmospheric lapse rate and mantle viscosity, the interaction of the GIA feedback and the melt-elevation feedback leads to self-sustained, long-term oscillations in ice-sheet volume with oscillation periods between 74 000 and over 300 000 years and oscillation amplitudes between 15 %-70 % of present-day ice volume.
This oscillatory regime reveals a possible mode of internal climatic variability in the Earth system on timescales on the order of 100 000 years that may be excited by or synchronized with orbital forcing or interact with glacial cycles and other slow modes of variability. Our findings are not meant as scenario-based near-term projections of ice losses but rather providing insight into of the feedback loops governing the "deep future" and, thus, long-term resilience of the Greenland Ice Sheet.
Y1 - 2022
U6 - https://doi.org/10.5194/esd-13-1077-2022
SN - 2190-4979
SN - 2190-4987
VL - 13
IS - 3
SP - 1077
EP - 1096
PB - Copernicus Publ.
CY - Göttingen
ER -
TY - JOUR
A1 - Albrecht, Torsten
A1 - Winkelmann, Ricarda
A1 - Levermann, Anders
T1 - Glacial-cycle simulations of the Antarctic Ice Sheet with the Parallel Ice Sheet Model (PISM)
BT - part 2: parameter ensemble analysis
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - The Parallel Ice Sheet Model (PISM) is applied to the Antarctic Ice Sheet over the last two glacial cycles (approximate to 210 000 years) with a resolution of 16 km. An ensemble of 256 model runs is analyzed in which four relevant model parameters have been systematically varied using full-factorial parameter sampling. Parameters and plausible parameter ranges have been identified in a companion paper (Albrecht et al., 2020) and are associated with ice dynamics, climatic forcing, basal sliding and bed deformation and represent distinct classes of model uncertainties. The model is scored against both modern and geologic data, including reconstructed grounding-line locations, elevation-age data, ice thickness, surface velocities and uplift rates. An aggregated score is computed for each ensemble member that measures the overall model-data misfit, including measurement uncertainty in terms of a Gaussian error model (Briggs and Tarasov, 2013). The statistical method used to analyze the ensemble simulation results follows closely the simple averaging method described in Pollard et al. (2016).
This analysis reveals clusters of best-fit parameter combinations, and hence a likely range of relevant model and boundary parameters, rather than individual best-fit parameters. The ensemble of reconstructed histories of Antarctic Ice Sheet volumes provides a score-weighted likely range of sea-level contributions since the Last Glacial Maximum (LGM) of 9.4 +/- 4.1m (or 6.5 +/- 2.0 x 10(6) km(3)), which is at the upper range of most previous studies. The last deglaciation occurs in all ensemble simulations after around 12 000 years before present and hence after the meltwater pulse 1A (MWP1a). Our ensemble analysis also provides an estimate of parametric uncertainty bounds for the present-day state that can be used for PISM projections of future sea-level contributions from the Antarctic Ice Sheet.
Y1 - 2020
U6 - https://doi.org/10.5194/tc-14-633-2020
SN - 1994-0416
SN - 1994-0424
VL - 14
IS - 2
SP - 633
EP - 656
PB - Copernicus Publ.
CY - Göttingen
ER -
TY - JOUR
A1 - Schlemm, Tanja
A1 - Feldmann, Johannes
A1 - Winkelmann, Ricarda
A1 - Levermann, Anders
T1 - Stabilizing effect of melange buttressing on the marine ice-cliff instability of the West Antarctic Ice Sheet
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - Owing to global warming and particularly high regional ocean warming, both Thwaites and Pine Island Glaciers in the Amundsen region of the Antarctic Ice Sheet could lose their buttressing ice shelves over time. We analyse the possible consequences using the parallel ice sheet model (PISM), applying a simple cliff-calving parameterization and an ice melange-buttressing model. We find that the instantaneous loss of ice-shelf buttressing, due to enforced ice-shelf melting, initiates grounding-line retreat and triggers marine ice sheet instability (MISI). As a consequence, the grounding line progresses into the interior of the West Antarctic Ice Sheet and leads to a sea level contribution of 0.6 m within 100 a. By subjecting the exposed ice cliffs to cliff calving using our simplified parameterization, we also analyse marine ice cliff instability (MICI). In our simulations it can double or even triple the sea level contribution depending on the only loosely constrained parameter that determines the maximum cliff-calving rate. The speed of MICI depends on this upper bound of the calving rate, which is given by the ice melange buttressing the glacier. However, stabilization of MICI may occur for geometric reasons. Because the embayment geometry changes as MICI advances into the interior of the ice sheet, the upper bound on calving rates is reduced and the progress of MICI is slowed down. Although we cannot claim that our simulations bear relevant quantitative estimates of the effect of ice-melange buttressing on MICI, the mechanism has the potential to stop the instability. Further research is needed to evaluate its role for the past and future evolution of the Antarctic Ice Sheet.
Y1 - 2022
U6 - https://doi.org/10.5194/tc-16-1979-2022
SN - 1994-0416
SN - 1994-0424
VL - 16
IS - 5
SP - 1979
EP - 1996
PB - Copernicus
CY - Göttingen
ER -
TY - JOUR
A1 - Feldmann, Johannes
A1 - Reese, Ronja
A1 - Winkelmann, Ricarda
A1 - Levermann, Anders
T1 - Shear-margin melting causes stronger transient ice discharge than ice-stream melting in idealized simulations
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - Basal ice-shelf melting is the key driver of Antarctica's increasing sea-level contribution. In diminishing the buttressing force of the ice shelves that fringe the ice sheet, the melting increases the ice discharge into the ocean.
Here we contrast the influence of basal melting in two different ice-shelf regions on the time-dependent response of an isothermal, inherently buttressed ice-sheet-shelf system. In the idealized numerical simulations, the basal-melt perturbations are applied close to the grounding line in the ice-shelf's (1) ice-stream region, where the ice shelf is fed by the fastest ice masses that stream through the upstream bed trough and (2) shear margins, where the ice flow is slower.
The results show that melting below one or both of the shear margins can cause a decadal to centennial increase in ice discharge that is more than twice as large compared to a similar perturbation in the ice-stream region. We attribute this to the fact that melt-induced ice-shelf thinning in the central grounding-line region is attenuated very effectively by the fast flow of the central ice stream. In contrast, the much slower ice dynamics in the lateral shear margins of the ice shelf facilitate sustained ice-shelf thinning and thereby foster buttressing reduction.
Regardless of the melt location, a higher melt concentration toward the grounding line generally goes along with a stronger response. Our results highlight the vulnerability of outlet glaciers to basal melting in stagnant, buttressing-relevant ice-shelf regions, a mechanism that may gain importance under future global warming.
Y1 - 2022
U6 - https://doi.org/10.5194/tc-16-1927-2022
SN - 1994-0416
SN - 1994-0424
VL - 16
IS - 5
SP - 1927
EP - 1940
PB - Copernicus
CY - Göttingen
ER -
TY - JOUR
A1 - Wunderling, Nico
A1 - Willeit, Matteo
A1 - Donges, Jonathan
A1 - Winkelmann, Ricarda
T1 - Global warming due to loss of large ice masses and Arctic summer sea ice
JF - Nature Communications
N2 - Several large-scale cryosphere elements such as the Arctic summer sea ice, the mountain glaciers, the Greenland and West Antarctic Ice Sheet have changed substantially during the last century due to anthropogenic global warming. However, the impacts of their possible future disintegration on global mean temperature (GMT) and climate feedbacks have not yet been comprehensively evaluated. Here, we quantify this response using an Earth system model of intermediate complexity. Overall, we find a median additional global warming of 0.43 degrees C (interquartile range: 0.39-0.46 degrees C) at a CO2 concentration of 400 ppm. Most of this response (55%) is caused by albedo changes, but lapse rate together with water vapour (30%) and cloud feedbacks (15%) also contribute significantly. While a decay of the ice sheets would occur on centennial to millennial time scales, the Arctic might become ice-free during summer within the 21st century. Our findings imply an additional increase of the GMT on intermediate to long time scales. The disintegration of cryosphere elements such as the Arctic summer sea ice, mountain glaciers, Greenland and West Antarctica is associated with temperature and radiative feedbacks. In this work, the authors quantify these feedbacks and find an additional global warming of 0.43 degrees C.
Y1 - 2020
U6 - https://doi.org/10.1038/s41467-020-18934-3
SN - 2041-1723
VL - 11
IS - 1
PB - Nature Publishing Group
CY - Berlin
ER -
TY - JOUR
A1 - Zeitz, Maria
A1 - Reese, Ronja
A1 - Beckmann, Johanna
A1 - Krebs-Kanzow, Uta
A1 - Winkelmann, Ricarda
T1 - Impact of the melt-albedo feedback on the future evolution of the Greenland Ice Sheet with PISM-dEBM-simple
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - Surface melting of the Greenland Ice Sheet contributes a large amount to current and future sea level rise. Increased surface melt may lower the reflectivity of the ice sheet surface and thereby increase melt rates: the so-called melt-albedo feedback describes this self-sustaining increase in surface melting. In order to test the effect of the melt-albedo feedback in a prognostic ice sheet model, we implement dEBM-simple, a simplified version of the diurnal Energy Balance Model dEBM, in the Parallel Ice Sheet Model (PISM). The implementation includes a simple representation of the melt-albedo feedback and can thereby replace the positive-degree-day melt scheme. Using PISM-dEBM-simple, we find that this feedback increases ice loss through surface warming by 60 % until 2300 for the high-emission scenario RCP8.5 when compared to a scenario in which the albedo remains constant at its present-day values. With an increase of 90 % compared to a fixed-albedo scenario, the effect is more pronounced for lower surface warming under RCP2.6. Furthermore, assuming an immediate darkening of the ice surface over all summer months, we estimate an upper bound for this effect to be 70 % in the RCP8.5 scenario and a more than 4-fold increase under RCP2.6. With dEBM-simple implemented in PISM, we find that the melt-albedo feedback is an essential contributor to mass loss in dynamic simulations of the Greenland Ice Sheet under future warming.
Y1 - 2021
U6 - https://doi.org/10.5194/tc-15-5739-2021
SN - 1994-0416
SN - 1994-0424
VL - 15
IS - 12
SP - 5739
EP - 5764
PB - Copernicus
CY - Katlenburg-Lindau
ER -
TY - JOUR
A1 - Klose, Ann Kristin
A1 - Wunderling, Nico
A1 - Winkelmann, Ricarda
A1 - Donges, Jonathan
T1 - What do we mean, 'tipping cascade'?
JF - Environmental research letters : ERL
N2 - Based on suggested interactions of potential tipping elements in the Earth's climate and in ecological systems, tipping cascades as possible dynamics are increasingly discussed and studied. The activation of such tipping cascades would impose a considerable risk for human societies and biosphere integrity. However, there are ambiguities in the description of tipping cascades within the literature so far. Here we illustrate how different patterns of multiple tipping dynamics emerge from a very simple coupling of two previously studied idealized tipping elements. In particular, we distinguish between a two phase cascade, a domino cascade and a joint cascade. A mitigation of an unfolding two phase cascade may be possible and common early warning indicators are sensitive to upcoming critical transitions to a certain degree. In contrast, a domino cascade may hardly be stopped once initiated and critical slowing down-based indicators fail to indicate tipping of the following element. These different potentials for intervention and anticipation across the distinct patterns of multiple tipping dynamics should be seen as a call to be more precise in future analyses of cascading dynamics arising from tipping element interactions in the Earth system.
KW - tipping cascade
KW - domino effect
KW - tipping interactions
KW - cascading regime
KW - shifts
KW - early warning indicators
Y1 - 2021
U6 - https://doi.org/10.1088/1748-9326/ac3955
SN - 1748-9326
VL - 16
IS - 12
PB - IOP Publ. Ltd.
CY - Bristol
ER -
TY - JOUR
A1 - Tiberius, Victor
A1 - Weyland, Michael
T1 - Identifying constituent elements of entrepreneurship curricula
BT - a systematic literature review
JF - Administrative sciences
N2 - Entrepreneurship education research has a strong “output” focus on impact studies but pays much less attention to the “inside” or process perspective of the way entrepreneurship education occurs. In particular, the scattered previous entrepreneurship curriculum research has not managed to provide a current and comprehensive overview of the curricular elements that constitute entrepreneurship education. To overcome this shortcoming, we aim to identify the teaching objectives, teaching contents, teaching methods, and assessment methods discussed in entrepreneurship curriculum research. To this end, we conducted a systematic literature review on the four entrepreneurship curriculum dimensions and collected all mentioned curriculum items. We used a two-stage coding procedure to find the genuinely entrepreneurship-specific items. Among numerous items (also from business management and other subjects), we found 26 objectives, 34 contents, 11 teaching methods, and 7 assessment methods that were entrepreneurship-specific. Most of these items were addressed by only a few scholarly papers.
KW - assessment methods
KW - curriculum
KW - entrepreneurship education
KW - teaching contents
KW - teaching methods
KW - teaching objectives
Y1 - 2023
U6 - https://doi.org/10.3390/admsci14010001
SN - 2076-3387
VL - 14
IS - 1
PB - MDPI
CY - Basel
ER -