Res. b, c, d and f, g, h annual glacier-wide MB probability distribution functions for all n scenarios in each RCP. Ecography 40, 913929 (2017). Nonlinear sensitivity of glacier mass balance to future climate change Rveillet, M. et al. Geosci. At present, using complex surface energy balance models for large-scale glacier projections is not feasible yet, mainly due to the lack of input data. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. MB rates only begin to approach equilibrium towards the end of the century under RCP 2.6, for which glaciers could potentially stabilize with the climate in the first decades of the 22nd century depending on their response time (Fig. Glacier landscapes are expected to see important changes throughout the French Alps, with the average glacier altitude becoming 300m (RCP 4.5) and 400m (RCP 8.5) higher than nowadays (Fig. Evol. 1a). As such, these values reflect both the climatic forcing and the changing glacier geometry. The largest snow depths measured this spring exceeded 10 meters on Nisqually Glacier and 7 meters on Emmons. . Sci. Hock, R. & Huss, M. Glaciers and climate change. At the Edge: Monitoring Glaciers to Watch Global Warming - NASA Nonetheless, these differences have been shown to be rather small, having a lower impact on results than climate forcings or the initial glacier ice thickness10. The maximum advance of Nisqually Glacier in the last thousand years was located, and retreat from this point is believed to have started about 1840. Several aquatic and terrestrial ecosystems depend on these water resources as well, which ensure a base runoff during the warmest or driest months of the year6. Glacier variations in response to climate change from 1972 to 2007 in 15 - Response of glaciers to climate change - Cambridge Core Conversely, the linear MB model appears to be over-sensitive to extreme positive and negative snowfall anomalies. Through his research in that area, he's seen firsthand the impact of climate change and has been studying the long-term effects of a warming planet. Map-based methods for estimating glacier equilibrium-line altitudes If material is not included in the articles Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. This will reduce the importance of shortwave radiation for future ablation rates, and it is expected to result in a reduction in values of degree-day factors (DDFs) and therefore a significant change in melt sensitivity to air temperature variations36. acknowledges the funding received from a EU Horizon 2020 Marie Skodowska-Curie Individual Fellowship (grant no. This work was funded by the Labex OSUG@2020 (Investissements davenir, ANR10 LABX56) and the Auvergne-Rhne-Alpes region through the BERGER project. Nature Communications (Nat Commun) 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. We perform, to the best of our knowledge, the first-ever deep learning (i.e. S5b). The climatic forcing comes from high-resolution climate ensemble projections from 29 combinations of global climate models (GCMs) and regional climate models (RCMs) adjusted for mountain regions for three Representative Concentration Pathway (RCP) scenarios: 2.6, 4.5, and 8.525. https://zenodo.org/record/5549758. Roberts, D. R. et al. "Such glaciers spawn icebergs into the ocean or lakes and have different dynamics from glaciers that end on land and melt at their front ends. S5cf), except for the largest glaciers (e.g. 21, 229246 (2021). Each one of these cross-validations served to evaluate the model performance for the spatial, temporal and both dimensions, respectively. Average ice velocities on the Nisqually Glacier were previously measured at approximately 200 mm/day (8 in) (Hodge 1974). "The Patagonia Icefields are dominated by so-called 'calving' glaciers," Rignot said. In order to do so, we applied a deterministic sampling process as a sensitivity analysis to both the deep learning and the Lasso MB models. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Photographs taken by Simo Rsnen (Bossons glacier, European Alps, CC BY-SA 3.0) and Doug Hardy (Quelccaya ice cap, Andes, CC BY-SA 4.0). Partitioning the uncertainty of ensemble projections of global glacier mass change. 4a). Alternatively, the comparisons against an independent large-scale glacier evolution model were less straightforward to achieve. J. Hosp. Soc. Internet Explorer). Interestingly, future warmer temperatures do not affect annual snowfall rates on glaciers as a result of both higher precipitation rates in the EURO-CORDEX ensemble (Fig. In order to investigate the implications of these results for flat glaciers, we performed additional synthetic experiments in order to reproduce this lack of topographical feedback (Fig. Data 12, 18051821 (2020). In order to investigate the effects of MB nonlinearities on flatter glaciers, we conducted a synthetic experiment using the French Alps dataset. regularized multilinear regression. Paul, F., Kb, A., Maisch, M., Kellenberger, T. & Haeberli, W. Rapid disintegration of Alpine glaciers observed with satellite data: disintegration of alpine glaciers. Smiatek, G., Kunstmann, H. & Senatore, A. EURO-CORDEX regional climate model analysis for the Greater Alpine Region: performance and expected future change: climate change in the gar area. Response of KarakoramHimalayan glaciers to climate variability and Lett. The estimated ice thickness for Mer de Glace (28.87km2 in 2015) was increased by 25% in order to correct the bias with respect to field observations31. See how Mount Rainier glaciers have vanished over time, with this eye Vincent, C. et al. Summer climate is computed between April 1st and September 30th and winter climate between October 1st and March 31st. 4a, b) and negative (Fig. Due to the statistical nature of the Lasso model, the response to snowfall anomalies is also highly influenced by variations in PDDs (Fig. GlacierMIP A model intercomparison of global-scale glacier mass-balance models and projections. 2015 IEEE Int. GloGEMflow has been previously applied in a study over the whole European Alps, and its temperature-index model was mainly calibrated with MB data from the Swiss Alps. Fundam. Immerzeel, W. W. et al. The effect of glaciers shrinking to smaller extents is not captured by these synthetic experiments, but this effect is less important for flat glaciers that are dominated by thinning (Fig. 48, 24872512 (2009). Mer de Glace, 29km2 in 2015), which did show important differences under RCP 8.5 (up to 75%), due to their longer response time. 14, 815829 (2010). Zekollari, H., Huss, M. & Farinotti, D. Modelling the future evolution of glaciers in the European Alps under the EURO-CORDEX RCM ensemble. 44, 13761383 (2017). Bolibar, J., Rabatel, A., Gouttevin, I. et al. These measurements of surface elevation were begun by personnel of the Tacoma For such cases, we assumed that ice dynamics no longer play an important role, and the mass changes were applied equally throughout the glacier. Particularly in Asia, water demand exceeds supply due to rapid population growth, with glacier . Atmospheres 121, 77107728 (2016). The rest of the story appears to lie primarily in the unique dynamic response of the region's glaciers to climate change. Univ. S5h, j, l). Vis. A comparison between the two MB models shows that a nonlinear response to climate forcings is captured by the deep learning MB model, allowing a better representation of glacier mass changes, including significantly reduced biases for extreme values (see Methods). Moreover these three aspects of glacier behavior are inextricably interwoven: a high sensitivity to climate change goes hand-in-hand with a large natural variability. In order to simulate annual glacier-wide MB values, (a) topographical and (b) climate data for those glaciers and years were compiled for each of the 1048 glacier-year values. Glacier topography is a crucial driver of future glacier projections and is expected to play an important role in determining the magnitude that nonlinearities will have on the mass balance signal: ice caps and large flatter glaciers are expected to be more influenced by these nonlinear sensitivities than steep mountain glaciers in a warming climate. Both the Lasso and the temperature-index MB model rely on linear relationships between PDDs, solid precipitation and MB. Nature 568, 382386 (2019). MathSciNet For that, a dataset of input predictors covering all the glaciers in the French Alps for the 19672015 period was generated from a past MB reconstruction study15. The processing chain for extracting glacier outlines from images is composed of four steps: (1) calculation of band ratio, (2) selection of threshold value, (3) creation of binary image and (4) manual digitization. performed simulations with another glacier model, provided results for comparison, and contributed to the glaciological analyses. energy balance), with differences increasing when the conditions considerably differ from the calibration period33. In fact, in many cases the surface lowering into warmer air causes this impact on the MB to be negative, further enhancing extreme negative mass balance rates. Mt. S6). Lett. To obtain South American Glaciers Melting Faster, Changing Sea Level 41, 153160 (1995). Glaciers smaller than 0.5km2 often display a high climate imbalance, with their equilibrium line being higher than the glaciers maximum altitude. 33, 645671 (2005). Climate Change Indicators: Glaciers | US EPA Our results indicate that these uncertainties might be even larger than we previously thought, as linear MB models are introducing additional biases under the extreme climatic conditions of the late 21st and 22nd centuries. You are using a browser version with limited support for CSS. B Methodol. Glaciers are experiencing important changes throughout the world as a consequence of anthropogenic climate change1. Taking into account that for several regions in the world about half of the glacierized volume will be lost during this first half of the 21st century, glacier models play a major role in the correct assessment of future glacier evolution. Rackauckas, C. et al. Since both MB models also include monthly temperature data as predictors, this CPDD anomaly was distributed evenly between the ablation season (April 1September 30), following the expected increase in mostly summer temperatures instead of winter temperatures in the future (Fig. This type of model uses a calibrated linear relationship between positive degree-days (PDDs) and the melt of ice or snow11. Magnin, F., Haeberli, W., Linsbauer, A., Deline, P. & Ravanel, L. Estimating glacier-bed overdeepenings as possible sites of future lakes in the de-glaciating Mont Blanc massif (Western European Alps). We compare model runs using a nonlinear deep learning MB model (the reference approach in our study) against a simplified linear machine learning MB model based on the Lasso30, i.e. On the one hand, MB nonlinearities for mountain glaciers appear to be only relevant for climate scenarios with a reduction in greenhouse gases emissions (Fig. Nat. & Galiez, C. A deep learning reconstruction of mass balance series for all glaciers in the French Alps: 19672015. 282, 104115 (2003). 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. C.G. deep artificial neural networks) glacier evolution projections by modelling the regional evolution of French alpine glaciers through the 21st century. Our results show that the mean elevation is far more variable than the kinematic ELA ( Fig. 1). Therefore, linear MB models present more limitations for projections of ice caps, showing a tendency to negative MB biases. A recent Northern Hemisphere temperature reconstruction indicates an oscillating temperature drop from A.D. 1000-1850 of about 0.2C with a subsequent and still continuing warming of nearly 0.8C ( 3 ). GLAMOS. NASA finds Asian glaciers slowed by ice loss - Climate Change: Vital

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