Impact of extreme melt events on the future mass balance of the Greenland Ice Sheet
Final Report Abstract
The Greenland Ice Sheet has lost mass at an accelerated rate over the past decades. Due to global warming, "continued ice loss during the 21st century is virtually certain for the Greenland Ice Sheet" (IPCC-SPM 2021). In addition, Greenland has been subject to significant extreme melt events in recent years. Melt events were particularly intense in 2010, 2012, 2015, and 2019. In 2012, nearly the entire surface of the ice sheet was covered by meltwater for several days. As climate change continues, such events are expected to become more frequent and also more intense due to atmospheric blocking. However, until now is has been unclear how extreme events affect the ice dynamics and whether a possible acceleration of ice flow due to extreme events could lead to additional ice loss from Greenland in the future. The main objective of DFG project was therefore to investigate the impact of extreme melt events on the future evolution of the Greenland ice sheet. The focus was on the immediate and long-term effects on the mass balance and ice dynamics, as well as on Greenland’s contribution to sea-level rise. A further aim was to assess the respective role of the expected increased frequency and intensity of individual melt events. Our research focused on the importance of the interaction between ice and atmosphere, which led to improvements of the surface module of the Parallel Ice Sheet Model (PISM). A major finding of the project is a quantification of the increased risk that extreme events pose to future mass loss from Greenland: our projections show that taking the dynamic effects of extreme melt events into account can increase the sea-level contribution until 2300 by up to half a meter. Another finding is the crucial role of the melt-elevation feedback in Greenland's overall mass loss. Coupling the ice sheet model PISM with the regional atmospheric model Modèle Atmosphérique Régional (MAR) allowed for a more accurate exploration of this feedback mechanism, revealing modifications in local atmospheric circulation due to changing ice-sheet morphology. Furthermore, we investigated the importance of the melt-albedo feedback, which involves darker ice surfaces leading to more melting. This process may be crucial in preconditioning extreme melt events. By introducing the diurnal Energy Balance Model (dEBM-simple) into PISM, the research showcased significant ice loss due to surface darkening by 2300, underlining the significance of the albedo effect. Overall, the project has advanced our understanding of the complex interplay between extreme melt events, ice sheet dynamics, and their implications for future sea-level rise. The successful coupling of the models and the insights into individual feedback mechanisms create a more comprehensive framework for studying regional impacts of extreme events in Greenland, and provide the basis to extend these insights to Antarctica in future research.
Publications
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AGU Fall Meeting (Virtual Event, 2020). Spread in flow parameters creates a large uncertainty in ice loss in a flow line setup and in simulations of the Greenland Ice Sheet.
Zeitz, M., Levermann, A. & Winkelmann, R.
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EGU General Assembly (Virtual Event, 2020). How will the Greenland Ice Sheet develop under extreme melt events? (virtual presentation)
Beckmann, J. & Winkelmann, R.
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Invited talk at European Security Seminar North at the George C. Marshall European Center for Security Studies (Garmisch-Partenkirchen, Germany, 2020). Climate change in the Arctic and its impact for the coming decades.
Beckmann, J.
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EGU General Assembly (Hybrid Event, 2021). Greenland mass balance by 2100 using a coupled atmospheric (MAR) and ice sheet (PISM) model (virtual presentation).
Delhasse, A., Beckmann, J. & Fettweis, X.
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Impact of the melt–albedo feedback on the future evolution of the Greenland Ice Sheet with PISM-dEBM-simple. The Cryosphere, 15(12), 5739-5764.
Zeitz, Maria; Reese, Ronja; Beckmann, Johanna; Krebs-Kanzow, Uta & Winkelmann, Ricarda
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EGU General Assembly (Vienna, Austria, 2022). Interacting feedbacks allow for distinct dynamic regimes of the Greenland Ice Sheet.
Zeitz, M., Haacker, J., Donges, J.F., Albrecht, T. & Winkelmann, R.
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ISMASS workshop on ‘Ice sheets: weather versus climate’ (Reykjavik, Iceland, 2022). The evolution of the Greenland Ice Sheet under extreme melt events.
Beckmann, J. & Winkelmann, R.
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Keynote at Discussion series led by WCRP, AIMES and the Earth Commission (2022). Tipping elements, irreversibility and abrupt change in ice sheets.
Winkelmann, R.
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Effects of extreme melt events on ice flow and sea level rise of the Greenland Ice Sheet. The Cryosphere, 17(7), 3083-3099.
Beckmann, Johanna & Winkelmann, Ricarda
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Coupling MAR (Modèle Atmosphérique Régional) with PISM (Parallel Ice Sheet Model) mitigates the positive melt–elevation feedback. The Cryosphere, 18(2), 633-651.
Delhasse, Alison; Beckmann, Johanna; Kittel, Christoph & Fettweis, Xavier
