C.G. 0.5) than lower values typical from ice34. Bolibar, J. ALPGM (ALpine Parameterized Glacier Model) v1.1. Ser. This means that these flatter ice bodies, under a warming climate, will be subject to higher temperatures than their steeper counterparts. Steiner, D., Walter, A. Millan, R., Mouginot, J., Rabatel, A., & Morlighem, M. Ice velocity and thickness of the worlds glaciers. During the last decade, various global glacier evolution models have been used to provide estimates on the future sea-level contribution from glaciers7,8. acknowledges the funding received from a EU Horizon 2020 Marie Skodowska-Curie Individual Fellowship (grant no. The position of the front of the wave will be defined as the transverse line across the glacier where the flow of . Rabatel, A., Sanchez, O., Vincent, C. & Six, D. Estimation of glacier thickness from surface mass balance and ice flow velocities: a case study on Argentire Glacier, France. This type of model uses a calibrated linear relationship between positive degree-days (PDDs) and the melt of ice or snow11. 2a and S3). Ice melt sensitivity to PDDs strongly decreases with increasing summer temperatures, whereas snow melt sensitivity changes at a smaller rate34. Relative performance of empirical and physical models in assessing the seasonal and annual glacier surface mass balance of Saint-Sorlin Glacier (French Alps). The vast majority of glaciers in the French Alps are very small glaciers (<0.01km2), that are mainly remnants from the Little Ice Age, with a strong imbalance with the current climate15. Sci. For these 32 glaciers, a total of 1048 annual glacier-wide MB values are available, covering the 19672015 period with gaps. Nature 568, 382386 (2019). Simulations were then performed by averaging the outputs of each one of the 60 ensemble members. This is not the case for the nonlinear deep learning MB model, which captures the nonlinear response of melt and MB to increasing air temperatures, thus reducing the MB sensitivity to extreme positive and negative air temperature and summer snowfall anomalies (Fig. Correspondence to Researchers analyzed almost 2 million satellite images of the glaciers and found that 94 . Earth Planet. Since these two glaciers are expected to be some of the few large glaciers that will survive the 21st century climate, an accurate representation of their initial ice thickness has an important effect on the estimates of remaining ice. Rackauckas, C. et al. glacier length12,14. Climate variations change a glacier's mass balance by affecting ablation and accumulation amounts. 185, 235246 (2014). Lett. Get the most important science stories of the day, free in your inbox. ADS 2008. Data 12, 19731983 (2020). This is particularly important for the ablation season and for ice DDFs, which need to accommodate the progressively decreasing role that shortwave radiation will play in the future glacier surface energy budget under warmer conditions. For this, a newly-developed state-of-the-art modelling framework based on a deep learning mass balance component and glacier-specific parametrizations of glacier changes is used. contributed to the extraction of nonlinear mass balance responses and to the statistical analysis. 4e) MB rates. We acknowledge the more than 50 years of glaciological monitoring performed by the GLACIOCLIM French National Observatory (https://glacioclim.osug.fr), which provided essential observations for our modelling study. Each one of these models was created by training a deep learning model with the full dataset except all data from a random glacier and year, and evaluating the performance on these hidden values. 799904) and from the Fonds de la Recherche Scientifique FNRS (postdoctoral grant charg de recherches). 4e). The Lasso30, used for the linear mass balance model, is a linear regression analysis method which shrinks model parameters, thus performing both variable selection and regularization.
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