Therefore, an alternative nonlinear parameterization for the reduction in MB sensitivity under increasing air temperatures would be useful. Glaciers smaller than 0.5km2 often display a high climate imbalance, with their equilibrium line being higher than the glaciers maximum altitude. Change 120, 2437 (2014). Huss, M. et al. J. Appl. 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. Our projections show a strong glacier mass loss for all 29 climate members, with average ice volume losses by the end of the century of 75%, 80%, and 88% compared to 2015 under RCP 2.6 (9%, n=3), RCP 4.5 (17% +11%, n=13) and RCP 8.5 (15% +11%, n=13), respectively (Fig. 5). J. Glaciol. Fluctuations of the Nisqually Glacier, Mt. Rainier, Washington, since During the last decade, various global glacier evolution models have been used to provide estimates on the future sea-level contribution from glaciers7,8. As climate changes, so do glaciers | PNAS 49, 26652683 (2017). Deep artificial neural networks (ANNs) are nonlinear models that offer an alternative approach to these classic methods. CPDD, winter snowfall or summer snowfall) was modified for all glaciers and years. The Nisqually Glacier, Mount Rainier, Washington, 1857-1979: A summary Other articles where Nisqually Glacier is discussed: Mount Rainier: from the broad summit, including Nisqually Glacier, whose retreat and advance over the last 150 years has helped scientists determine patterns in the Earth's climate. Glaciers - Mount Rainier National Park (U.S. National Park Service) is central to a glacier's response: Fig.2ashows 1L.t/for a warming trend of 1 C per century, for three glaciers with dierent (and fixed ). https://doi.org/10.5281/zenodo.3609136. The images or other third party material in this article are included in the articles Creative Commons license, unless indicated otherwise in a credit line to the material. Clim. The Nature of Kinematic Waves in Glaciers and their Application to 48, 24872512 (2009). An analysis of the climate signal at the glaciers mean altitude throughout the century reveals that air temperature, particularly in summer, is expected to be the main driver of glacier mass change in the region (Fig. In Climate Change 157176 (Elsevier, 2021). J.B. developed the main glacier model, performed the simulations, analysed the results, and wrote the paper. Maussion, F. et al. Front. A physically-based method for mapping glacial debris-cover thickness from ASTER satellite imagery: development and testing at Miage Glacier, Italian Alps Discovery - the University of Dundee Research Portal 51, 313323 (2005). Peer reviewer reports are available. On Mount Rainier, elevation surveys of Nisqually Glacier are regularly made to determine changes in the elevation of the surface. 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. 2013). Geomorphology 350, 106913 (2020). Predicting future glacier evolution is of paramount importance in order to correctly anticipate and mitigate the resulting environmental and social impacts. GlaciersUnderstanding Climate Drivers | U.S. Geological Survey J. Glaciol. On the one hand, this improves our confidence in long-term MB projections for steep glaciers made by most GlacierMIP models for intermediate and high emissions climate scenarios. Geosci. 36, L23501 (2009). The glacier ice volume in the French Alps at the beginning of the 21st century is unevenly distributed, with the Mont-Blanc massif accounting for about 60% of the total ice volume in the year 2015 (7.06 out of 11.64km3, Fig. ICCV (2015) https://doi.org/10.1109/iccv.2015.123. (Zenodo, 2020). Therefore, we were capable of isolating the different behaviours of the nonlinear deep learning model and a linear machine learning model based on the Lasso30. Interestingly, our analysis indicates that more complex models using separate DDFs for ice, firn and snow might introduce stronger biases than more simple models using a single DDF. Fundam. 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. In order to overcome these differences, some adaptations were performed to the GloGEMflow output, accompanied with some hypotheses to ensure a realistic comparison. & Zumbhl, H. J. Long-term historical interactions between French society and glaciers have developed a dependency of society on them for water resources, agriculture, tourism18particularly the ski business19and hydropower generation. Geophys. Geophys. A well-established parametrization based on empirical functions50 was used in order to redistribute the annually simulated glacier-wide mass changes over each glacier. The dataset of initial glacier ice thickness, available for the year 2003, determines the starting point of our simulations. Pellicciotti, F. et al. S7). Universal Differential Equations for Scientific Machine Learning. 3c). Rising Water Temperatures Could Be A Death Sentence For Pacific Salmon The first main difference is related to the climate data used to force the models. 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. creates a Nisqually Glacier response similar to those seen from its historical waves, suggesting that there are other factors contributing to kinematic wave formation, and 4) the Nisqually . Climate Change 2013: The Physical Science Basis. Loss of glaciers contributes to sea-level rise, creates environmental hazards and can alter aquatic habitats. Google Scholar. Our previous work31 has shown that linear MB models can be correctly calibrated for data around the mean temperature and precipitation values used during training, giving similar results and performance to deep learning. S5b). Our projections highlight the almost complete disappearance of all glaciers outside the Mont-Blanc and Pelvoux (Ecrins region) massifs under RCP 4.5 (Fig. Studies have warned about the use of temperature-index models for snow and ice projections under climate change for decades34,35,36. Average ice velocities on the Nisqually Glacier were previously measured at approximately 200 mm/day (8 in) (Hodge 1974). Evol. Xu, B., Wang, N., Chen, T. & Li, M. Empirical Evaluation of Rectified Activations in Convolutional Network. This allows us to assess the MB models responses at a regional scale to changes in individual predictors (Fig. 2a). Glacier response to climate change Jim Salinger, Trevor Chinn, Andrew Willsman, and how fluctuations in New Zealand glaciers reflect regional climate change. See how Mount Rainier glaciers have vanished over time, with this eye Nisqually Glacier is the lengthiest of any made in North America. 1). These bulges, called kinematic waves, form when higher than normal snowfall builds up in the accumulation area of the glacier (c). Ioffe, S. & Szegedy, C. Batch Normalization: Accelerating Deep Network Training by Reducing Internal Covariate Shift (2015). These different behaviours and resulting biases can potentially induce important consequences in long-term glacier evolution projections. Botanical Evidence of the Modern History of Nisqually Glacier - USGS Due to the statistical nature of the Lasso model, the response to snowfall anomalies is also highly influenced by variations in PDDs (Fig. Glacier variations in response to climate change from 1972 to 2007 in 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. McKinley, Alaska, change in response to the local climate. Lett. The initial glacier ice thickness data for the year 2003 also differs slightly between both models. A small ablation increase may cause . GLAMOS. This work was funded by the Labex OSUG@2020 (Investissements davenir, ANR10 LABX56) and the Auvergne-Rhne-Alpes region through the BERGER project. CAS Nature Communications thanks Mohd Anul Haq, Lauren Vargo, and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Despite the existence of a wide variety of different approaches to simulate glacier dynamics, all glacier models in GlacierMIP rely on MB models with linear relationships between PDDs and melt, and precipitation and accumulation. C.G. Glaciers are experiencing important changes throughout the world as a consequence of anthropogenic climate change1. Geophys. 3). 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. Relative performance of empirical and physical models in assessing the seasonal and annual glacier surface mass balance of Saint-Sorlin Glacier (French Alps). Despite their limitations, temperature-index models, owing to their simplicity and parsimonious data requirements, have been widely used for large-scale glacier projections7,8. In order to avoid overfitting, MB models were thoroughly cross-validated using all data for the 19672015 period in order to ensure a correct out-of-sample performance. Glacier surface mass changes are commonly modelled by relying on empirical linear relationships between PDDs and snow, firn or ice melt8,9,10,29. Nisqually Glacier | glacier, Washington, United States Climate predictors consist of: the annual CPDD, winter snowfall, summer snowfall, monthly mean temperature and monthly snowfall. A consensus estimate for the ice thickness distribution of all glaciers on Earth. P. Kennard, J. The Cryosphere 13, 11251146 (2019). 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. J. Hosp. 3, 16751685 (2019). glacier length12,14. This suggests that linear MB models are adequate tools for simulating MB of mountain glaciers with important topographical adjustment, with the only exception being the most optimistic climate scenarios and glaciers with long response times. As we have previously shown, these models present a very similar behaviour to the linear statistical MB model from this study (Fig. Through synthetic experiments, we showed that the associated uncertainties are likely to be even more pronounced for ice caps, which host the largest reserves of ice outside the two main ice sheets32. Model Dev. Thank you for visiting nature.com. 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. A sensitivity analysis of both MB models revealed nonlinear relationships between PDDs, snowfall (in winter and summer) and glacier-wide MB, which the linear model was only able to approximate (r2=0.41 for the Lasso vs. r2=0.76 for deep learning in cross-validation31; Fig. 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. Alternatively, the comparisons against an independent large-scale glacier evolution model were less straightforward to achieve.
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