In recent years, shrinking glaciers have contributed to about 30% of global sea level rise 1. Ice thickness data for Argentire glacier (12.27km2 in 2015) was taken from a combination of field observations (seismic, ground-penetrating radar or hot-water drilling53) and simulations32. This means that these differences linked to MB nonlinearities observed in this experiment could be even greater for such ice caps. 5). H.Z. longwave radiation budget, turbulent fluxes), in comparison with a future warmer climate. Differences for individual glaciers can be much more pronounced, as large and flat glaciers will have topoclimatic configurations that produce more extreme MB rates than small and steep glaciers with a short response time. This method has the advantage of including glacier-specific dynamics in the model, encompassing a wide range of different glacier behaviours. All these glacier models, independently from their approach, need to resolve the two main processes that determine glacier evolution: (1) glacier mass balance, as the difference between the mass gained via accumulation (e.g. Finally, there are differences as well in the glacier dynamics of both models, with ALPGM using a glacier-specific parameterized approach and GloGEMflow explicitly reproducing the ice flow dynamics. Scand. regularized multilinear regression. Bartk, B. et al. The Cryosphere 14, 565584 (2020). However, glacier projections under low-emission scenarios and the behaviour of flatter glaciers and ice caps are likely to be biased by mass balance models with linear sensitivities, introducing long-term biases in sea-level rise and water resources projections. Presentation at 2008 National Hydraulic Engineering . Nisqually Glacier is the lengthiest of any made in North America. This work was funded by the Labex OSUG@2020 (Investissements davenir, ANR10 LABX56) and the Auvergne-Rhne-Alpes region through the BERGER project. Change 120, 2437 (2014). Our analysis suggests that due to this positive impact on the MB signal, only relevant differences are observed between nonlinear and linear MB models for the lowest emission climate scenarios (Fig. "The Patagonia Icefields are dominated by so-called 'calving' glaciers," Rignot said. Additionally, glacier surface area was found to be a minor predictor in our MB models31. These conclusions drawn from these synthetic experiments could have large implications given the important sea-level contribution from ice cap-like ice bodies8. Massifs without glaciers by 2100 are marked with a cross, b Glacier ice volume distribution per massif, with its remaining fraction by 2100 (with respect to 2015), c Annual glacier-wide MB per massif, d Annual snowfall per massif, e Annual cumulative positive degree-days (CPDD) per massif. Correspondence to Previous studies on 21st century large-scale glacier evolution projections have covered the French Alps7,8. (Photograph by Klaus J. Bayr, Keene State College, 1990) One method of measuring glaciers is to send researchers onto the ice with . 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. Use the Previous and Next buttons to navigate the slides or the slide controller buttons at the end to navigate through each slide. Model Dev. The two models with linear MB responses to PDDs and accumulation simulate more positive MB rates under RCP 2.6, highlighting their over-sensitivity to negative air temperature anomalies and positive snowfall anomalies (Fig. This behaviour has already been observed for the European Alps, with a reduction in DDFs for snow during the ablation season of 7% per decade34. J. Glaciol. This oversensitivity directly results from the fact that temperature-index models rely on linear relationships between PDDs and melt and that these models are calibrated with past MB and climate data. This synthetic experiment is an approximation of what might occur in other glacierized regions with ice caps. Additionally, the specific responses of the deep learning and Lasso MB models to air temperature and snowfall were extracted by performing a model sensitivity analysis. Marzeion, B. et al. We further assessed the effect of MB nonlinearities by comparing our simulated glacier changes with those obtained from other glacier evolution studies from the literature, which rely on temperature-index models for MB modelling. 5). S8 and Fig. Greenland's melting glaciers, which plunge into Arctic waters via steep-sided inlets, or fjords, are among the main contributors to global sea level rise in response to climate change. Provided by the Springer Nature SharedIt content-sharing initiative. (b) Climate predictors are based on climatic anomalies computed at the glaciers mean altitude with respect to the 19672015 reference period mean values. 3 (2015). He, K., Zhang, X., Ren, S. & Sun, J. Delving Deep into Rectifiers: Surpassing Human-Level Performance on ImageNet Classification. An accurate prediction of future glacier evolution will be crucial to successfully adapt socioeconomic models and preserve biodiversity. Glacier variations in response to climate change from 1972 to 2007 in Response of KarakoramHimalayan glaciers to climate variability and Map-based methods for estimating glacier equilibrium-line altitudes Our results serve as a strong reminder that the outcomes of existing large-scale glacier simulations should be interpreted with care, and that newly available techniques (such as the nonlinear deep learning approach presented here) and observations (e.g. J. Glaciol. Thus, glacier sensitivity to a step change in climate , glacier response to climate trends , and glacier variance driven by stochastic climate fluctuations are all proportional to , making an important number to constrain. We perform, to the best of our knowledge, the first-ever deep learning (i.e. Solved Activity 13.3 Nisqually Glacier Response to Climate - Chegg 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. Nisqually Glacier is well known for its kinematic waves ( Meier, 1962 ), but its mass balance has never been measured due to the difficulty of the glacier terrain. Front. Clim. J.B. developed the main glacier model, performed the simulations, analysed the results, and wrote the paper. 22, 21462160 (2009). Advances occurred from 1963-68 and from 1974-79. Arch. 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. Roe, G. H. Orographic precipitation. These results are in agreement with the main known drivers of glacier mass change in the French Alps28. S5cf), except for the largest glaciers (e.g. Glaciers in the European Alps have been monitored for several decades, resulting in the longest observational series in the world23,24. A globally complete, spatially and temporally resolved estimate of glacier mass change: 2000 to 2019. https://meetingorganizer.copernicus.org/EGU2020/EGU2020-20908.html (2020) https://doi.org/10.5194/egusphere-egu2020-20908. J. Hosp. Simulations for projections in this study were made by generating an ensemble of 60 cross-validated models based on LSYGO. This reduced sensitivity is captured through the response to summer snowfall anomalies, since the sensitivity to positive CPDD anomalies is quite similar for the linear and nonlinear models, as it encompasses both the accumulation and ablation seasons (Fig. In our model, we specifically computed this parameterized function for each individual glacier larger than 0.5km2, representing 80% of the total glacierized area in 2015, using two DEMs covering the whole French Alps: a photogrammetric one in 1979 and a SPOT-5 one in 2011. A similar trend is under way. Each one of these cross-validations served to evaluate the model performance for the spatial, temporal and both dimensions, respectively. Particularly in Asia, water demand exceeds supply due to rapid population growth, with glacier . Durand, Y. et al. Climate change spells disaster for the world's glaciers : NPR Earth Sci. 1). Tests were performed distributing the CPDD anomalies equally among all months of the year with very similar results. contributed to the extraction of nonlinear mass balance responses and to the statistical analysis. Here, with our newly presented approach, we were able for the first time to quantify the effect that stationary parameters in temperature-index mass balance models have on transient glacier evolution. 5). S5h, j, l). 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. By performing glacier projections both with mountain glaciers in the French Alps and a synthetic experiment reproducing ice cap-like behaviour, we argue that the limitations identified here for linear models will also have implications for many other glacierized regions in the world. Both machine learning MB models were trained with exactly the same data coming from the 1048 annual glacier-wide MB values, and both were cross-validated using LSYGO. The training was performed with an RMSprop optimizer, batch normalization46, and we used both dropout and Gaussian noise in order to regularize it. Dyn. This reanalysis is specifically designed to represent meteorological conditions over complex mountain terrain, being divided by mountain massif, aspect and elevation bands of 300m. Winter climate data are computed between October 1 and March 31, and summer data between April 1 and September 30. 6 (2018). How Will Melting Glaciers Affect Streamflow? - Eos 4e and 5). Glacier Research on Mt. Rainier - Portland State University 51, 573587 (2005). 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. a1) over the French Alps. These differences in the received climate signal are explained by the retreat of glaciers to higher altitudes, which keep up with the warming climate in RCP 4.5 but are outpaced by it under RCP 8.5. a Glacier-wide annual MB, b Ice volume, c Glacier area. Nat Commun 13, 409 (2022). 3c). Analyses were made of the annual photographs . the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Despite the existence of slightly different trends during the first half of the century, both the Lasso and the temperature-index model react similarly under RCP 4.5 and 8.5 during the second half of the century, compared to the deep learning model. Simulating these processes at a large geographical scale is challenging, with models requiring several parametrizations and simplifications to operate. The scheme simulates the mass balance as well as changes of the areal . Global-scale hydrological response to future glacier mass loss 60, 11401154 (2014). Anyone you share the following link with will be able to read this content: Sorry, a shareable link is not currently available for this article. Glacier surface mass changes are commonly modelled by relying on empirical linear relationships between PDDs and snow, firn or ice melt8,9,10,29. These bulges, called kinematic waves, form when higher than normal snowfall builds up in the accumulation area of the glacier (c). Due to the statistical nature of the Lasso model, the response to snowfall anomalies is also highly influenced by variations in PDDs (Fig. Nisqually Glacier - glaciers.pdx.edu Nisqually Glacier - Wikipedia CAS a1 and a r2 of 0.69, explaining 69% of the total MB variance. Since the neural network used here virtually behaves like a black box, an alternative way is needed to understand the models behaviour. Since the climate and glacier systems are known to be nonlinear13, we investigate the benefits of using a model treating, among others, PDDs in a nonlinear way in order to simulate annual glacier-wide MB at a regional scale. Models were trained using the SAFRAN reanalysis dataset47, including observations of mountain regions in France for the 19582015 period. Rising Water Temperatures Could Be A Death Sentence For Pacific Salmon This dataset applies a statistical adjustment specific to French mountain regions based on the SAFRAN dataset, to EURO-CORDEX26 GCM-RCM-RCP members, covering a total of 29 different future climate scenarios for the 20052100 period. Regarding air temperature forcings, the linear Lasso MB model was found to be slightly under-sensitive to extreme positive cumulative PDD (CPDD) and over-sensitive to extreme negative CPDDs. Sci. New research suggests that climate change-induced melting of the Nisqually Glacier near Seattle, Wash., and other high-elevation glaciers will offset seasonal declines in streamflow until. 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 . However, both the climate and glacier systems are known to react non-linearly, even to pre-processed forcings like PDDs13, implying that these models can only offer a linearized approximation of climate-glacier relationships. This removes the topographical feedback typical from mountain glaciers, and reproduces the more extreme climate conditions that ice caps are likely to endure through the 21st century40. This adjustment represents a major improvement over most climate data used to force regional and global glacier models. Nature 577, 364369 (2020). The dataset of initial glacier ice thickness, available for the year 2003, determines the starting point of our simulations. On top of that, they happen to be among the glacierized regions with the largest projected uncertainties8. Lett. 3). Jordi Bolibar. Conversely, the linear MB model appears to be over-sensitive to extreme positive and negative snowfall anomalies. Zekollari, H., Huss, M. & Farinotti, D. Modelling the future evolution of glaciers in the European Alps under the EURO-CORDEX RCM ensemble. Geosci. We performed a validation simulation for the 20032015 period by running our model through this period and comparing the simulated glacier surface area of each of the 32 glaciers with MB to observations from the 2015 glacier inventory16,52. 2a and S3). 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. Farinotti, D. et al. 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. 14, 815829 (2010). Glaciers with the greatest degree of seasonality in their flow behavior, such as Nisqually and Shoestring glaciers, responded most rapidly. 1 and S1). S5b). Univ. Our results point out that this lack of topographical feedback leads to an increased frequency of extreme negative MB rates and to more pronounced differences between the nonlinear and linear MB models (Figs. A small ablation increase may cause . To obtain CAS Predicting future glacier evolution is of paramount importance in order to correctly anticipate and mitigate the resulting environmental and social impacts. Both the Lasso and the temperature-index MB model rely on linear relationships between PDDs, solid precipitation and MB. For such cases, we assumed that ice dynamics no longer play an important role, and the mass changes were applied equally throughout the glacier. A global synthesis of biodiversity responses to glacier retreat. Bolibar, J., Rabatel, A., Gouttevin, I. et al. The Cryosphere 12, 13671386 (2018). Remote Sens. Glob. This annual geometry adjustment accounts for the effects of glacier retreat on the climate signal received by glaciers. Climate predictors consist of: the annual CPDD, winter snowfall, summer snowfall, monthly mean temperature and monthly snowfall. The anomaly in snowfall was evenly distributed for every month in the accumulation (October 1April 31) and ablation seasons, respectively. Ecography 40, 913929 (2017). Ice melt sensitivity to PDDs strongly decreases with increasing summer temperatures, whereas snow melt sensitivity changes at a smaller rate34. Vis. J. Glaciol. Sci. The ice thickness data for two of the largest glaciers in the French Alps were modified in order to improve data quality. Despite the differences in the two modelling approaches (TableS2), both regional glacier volume projections present relatively similar results by the end of the century, with volume differences ranging between 14% for RCP 2.6 to less than 2% for RCP 4.5 (Fig. Google Scholar. 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. 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. CoRR abs/1505.00853 (2015). Glaciers are important for agriculture, hydropower, recreation, tourism, and biological communities. The temperature-index model includes up to three different DDFs, for ice, firn and snow, resulting in three parameters. 0.78m.w.e. We argue that such models can be suitable for steep mountain glaciers. Steiner, D., Walter, A. Huss, M. et al. J. Glaciol. Millan, R., Mouginot, J., Rabatel, A., & Morlighem, M. Ice velocity and thickness of the worlds glaciers. (Springer, New York, 2009). 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. snowfall, avalanches and refreezing) and the mass lost via different processes of ablation (e.g. Universal Differential Equations for Scientific Machine Learning. Without these cold water resources during the hottest months of the year, many aquatic and terrestrial ecosystems will be impacted due to changes in runoff, water temperature or habitat humidity6,21,22. Hock, R. & Huss, M. Glaciers and climate change. This behaviour is expected for mountain glaciers, as they are capable of retreating to higher altitudes, thus producing a positive impact on their glacier-wide MB (Fig. 3). The Karakoram and the Himalayan mountain range accommodate a large number of glaciers and are the major source of several perennial rivers downstream. For intermediate and pessimistic climate scenarios, no significant differences were found (Fig. Future high-mountain hydrology: a new parameterization of glacier retreat. Seasonal Arctic sea ice forecasting with probabilistic deep learning, Global glacier mass changes and their contributions to sea-level rise from 1961 to 2016, Two decades of glacier mass loss along the Andes, Centennial response of Greenlands three largest outlet glaciers, Accelerated global glacier mass loss in the early twenty-first century, High Mountain Asian glacier response to climate revealed by multi-temporal satellite observations since the 1960s, Rapid glacier retreat and downwasting throughout the European Alps in the early 21st century, Ice velocity and thickness of the worlds glaciers, Constraining glacier elevation and mass changes in South America, https://meetingorganizer.copernicus.org/EGU2020/EGU2020-20908.html, https://doi.org/10.5194/egusphere-egu2020-20908, https://doi.org/10.18750/MASSBALANCE.2019.R2019, https://doi.org/10.1016/B978-0-12-821575-3.00009-8, https://doi.org/10.1038/s41561-021-00885-z, http://creativecommons.org/licenses/by/4.0/, Unabated wastage of the Muz Taw Glacier in the Sawir Mountains during 19592021. On Mount Rainier, elevation surveys of Nisqually Glacier are regularly made to determine changes in the elevation of the surface. Our results suggest that, except for the lowest emissions climate scenarios and for large glaciers with long response times, MB models with linear relationships for PDDs and precipitation are suitable for mountain glaciers with a marked topographical feedback. https://doi.org/10.5281/zenodo.3609136. Ten . When using the linear MB model (Lasso), glaciers are close to reaching an equilibrium with the climate in the last decades of the century, which is not the case for the nonlinear MB model (deep learning). contributed to the climate analyses. Ice caps in the Canadian Arctic, the Russian Arctic, Svalbard, and parts of the periphery of Greenland are major reservoirs of ice, as well as some of the biggest expected contributors to sea level rise outside the two polar ice sheets7. https://zenodo.org/record/5549758. The application of a non-linear back-propagation neural network to study the mass balance of Grosse Aletschgletscher, Switzerland. Consequently, a simple MB model with a single DDF (e.g. Alternatively, the Lasso model used here includes 13 DDFs: one for the annual CPDDs and 12 for each month of the hydrological year. Earth Planet. ice cap-like behaviour). the Open Global Glacier Model - OGGM9) is likely to be less affected by an over-sensitivity to future warming than a more complex model with dedicated DDFs for ice, snow, and firn. 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. April 17, 2019. On the other hand, ice caps present a different response to future warming, with our results suggesting a negative MB bias by models using linear PDD and accumulation relationships. The Elements of Statistical Learning. Cite this article. P. Kennard, J. Some of these models use a single DDF, while others have separate DDFs for snow and ice, producing a piecewise function composed of two linear sub-functions that can partially account for nonlinear MB dynamics depending on the snowpack. S1a). Regarding air temperature, a specific CPDD anomaly ranging from 1500 PDD to +1500 PDD in steps of 100 PDD was prescribed to all glaciers for each dataset copy. However, as shown in our previous work and confirmed here, the accuracy of linear models drastically drops as soon as the input climate data diverges from the mean cluster of values used for training. Earth Syst. Consortium, R. G. I. Randolph Glacier Inventory 6.0 (2017) https://doi.org/10.7265/N5-RGI-60. Our results confirm an over-sensitivity of temperature-index models, often used by large-scale studies, to future warming. ISSN 2041-1723 (online). Explore awards | National Oceanic and Atmospheric Administration The vertical blue and red lines indicate the distribution of extreme (top 5%) values for all 21st century projected climate scenarios, with the mean value in the center and 1 indicated by dashed lines. Glacier response to climate perturbations: an accurate linear geometric This approach is known as a cross-validation ensemble49. Bolibar, J. et al. Interestingly, this matches the nonlinear, less sensitive response to summer snowfall in the ablation season of our deep learning model (Fig. 41, 153160 (1995). All values correspond to ensemble means under RCP 4.5. Robinson, C. T., Thompson, C. & Freestone, M. Ecosystem development of streams lengthened by rapid glacial recession. Nonlinear sensitivity of glacier mass balance to future climate change unveiled by deep learning. Ser. Earths Future 5, 418435 (2017). 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. An enhanced temperature-index glacier melt model including the shortwave radiation balance: development and testing for Haut Glacier dArolla, Switzerland. Earth Syst. Climate Change Indicators: Glaciers | US EPA Glacier response to climate change Jim Salinger, Trevor Chinn, Andrew Willsman, and how fluctuations in New Zealand glaciers reflect regional climate change. S7). 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 Studies have warned about the use of temperature-index models for snow and ice projections under climate change for decades34,35,36. 2a).