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You are here: Home / Events / Seminars / Seminaires Septembre 2019-Août 2020 / Vendredi 20 Décembre - Present - day and projected future trends for ice sheet contributions to sea level

Vendredi 20 Décembre - Present - day and projected future trends for ice sheet contributions to sea level

by SEMSOU last modified Dec 03, 2019 12:46 PM
When Dec 20, 2019
from 11:00 AM to 12:00 PM
Where salle Coriolis
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Jonathan Bamber

Bristol University, UK

 

Title: Present-day and projected future trends for ice sheet contributions to sea level

 

Abstract: Despite considerable advances in process understanding, numerical modeling and the quality of the observational record of ice sheet contributions to sea level rise (SLR) since the last IPCC report (AR5), severe limitations remain in the predictive capability of numerical modeling approaches. In this context, the potential contribution of the ice sheets remains the largest uncertainty in projecting future SLR beyond mid-century. Various approaches, including Monte Carlo ensemble emulator simulations, probabilistic or plausibility methods, and Semi Empirical Models have been used in attempts to address these limitations. To explore and quantify the uncertainties in ice sheet projections since the AR5, a Structured Expert Judgement (SEJ) exercise - involving 23 experts from North America and Europe - was undertaken in 2018.

The results of the SEJ indicated that estimates, particularly for probabilities beyond the likely range used in the AR5 (the 17th-83rd percentile), have grown since the AR5. The results indicated a 5% probability that global mean sea level could exceed 2 m by 2100, for a business-as-usual temperature scenario, with the ice sheets contributing 178 cm. The study elicited contributions for three processes - ice dynamics, accumulation and runoff-for each of the three ice sheets covering Greenland, West and East Antarctica. Here, we investigate the origins of the increased estimates relative to earlier studies and, in particular, the physical processes causing the long upper tails in the probability density functions for each ice sheet and their integrated response. To interpret the findings, we draw on process-based rationales, provided by the experts, which relate ice sheet SLR contributions to ocean and atmospheric forcing and to internal instabilities. Finally, we link the elicited ice sheet contributions to regional SLR response patterns, and we place these results in the context of the most recent SLR projections from other approaches.

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