contributed to the extraction of nonlinear mass balance responses and to the statistical analysis. Carlson, B. The main reason for their success comes from their suitability to large-scale studies with a low density of observations, in some cases displaying an even better performance than more complex models12. 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. 4). Geosci. This behaviour is not observed with the nonlinear model, hinting at a positive bias of linear MB models under RCP 2.6. The lower fraction of variance explained by linear models is present under all climate scenarios. GlaciersUnderstanding Climate Drivers | U.S. Geological Survey Relative performance of empirical and physical models in assessing the seasonal and annual glacier surface mass balance of Saint-Sorlin Glacier (French Alps). Xu, B., Wang, N., Chen, T. & Li, M. Empirical Evaluation of Rectified Activations in Convolutional Network. 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. When working with spatiotemporal data, it is imperative to respect spatial and temporal data structures during cross-validation in order to correctly assess an accurate model performance48. 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. Recent efforts have been made to improve the representation of ice flow dynamics in these models, replacing empirical parametrizations with simplified physical models9,10. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Geosci. 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. Cross-validation strategies for data with temporal, spatial, hierarchical, or phylogenetic structure. Uncertainties of existing projections of future glacier evolution are particularly large for the second half of the 21st century due to a large uncertainty on future climatic conditions. a1) over the French Alps. A dataset of 32 glaciers with direct annual glacier-wide MB observations and remote sensing estimates was used to train the models. 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. Loss of glaciers contributes to sea-level rise, creates environmental hazards and can alter aquatic habitats. Rveillet, M. et al. 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 ). Earth Sci. Winter tourism under climate change in the Pyrenees and the French Alps: relevance of snowmaking as a technical adaptation. 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. Therefore, an alternative nonlinear parameterization for the reduction in MB sensitivity under increasing air temperatures would be useful. Response of KarakoramHimalayan glaciers to climate variability and Thin lines represent each of the 29 individual member runs, while the thick lines represent the average for a given RCP. Gaining a better understanding of how warming ocean water affects these glaciers will help improve predictions of their fate. 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. Rainier is considered by the USGS to be one of the most threatening volcanoes in the Cascade Mountains. 65, 453467 (2019). However, the impact of different climate configurations, such as a more continental and drier climate or a more oceanic and humid climate, would certainly have an impact on the results, albeit a much less important one than the lack of topographical feedback explored here. This method has the advantage of including glacier-specific dynamics in the model, encompassing a wide range of different glacier behaviours. The Multitrophic Effects of Climate Change and Glacier Retreat - JSTOR However, the use of ANNs remains largely unexplored in glaciology for regression problems, with only a few studies using shallow ANNs for predicting the ice thickness14 or mass balance13 of a single glacier. 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 adjustment represents a major improvement over most climate data used to force regional and global glacier models. Provided by the Springer Nature SharedIt content-sharing initiative. The ice thickness data for two of the largest glaciers in the French Alps were modified in order to improve data quality. Bolibar, J. et al. Simulations were then performed by averaging the outputs of each one of the 60 ensemble members. Our synthetic experiment does not account for glacier surface area shrinking either, which might have an impact on the glacier-wide MB signal. This has the strongest impact under RCP 2.6, where positive MB rates are more frequent (Fig. A.R. 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. Therefore, solid precipitation is projected to remain almost constant at the evolving glaciers mean altitude independently from the future climate scenarios, while air temperature is projected to drive future glacier-wide mass changes (Fig. Rising Water Temperatures Could Be A Death Sentence For Pacific Salmon Consortium, R. G. I. Randolph Glacier Inventory 6.0 (2017) https://doi.org/10.7265/N5-RGI-60. S8 and Fig. Vertical axes are different for the two analyses. Peer reviewer reports are available. Fluctuations of the Nisqually Glacier, Mt. Rainier, Washington, since https://zenodo.org/record/5549758. Atmospheres 121, 77107728 (2016). 3). Clarke, G. K. C., Berthier, E., Schoof, C. G. & Jarosch, A. H. Neural networks applied to estimating subglacial topography and glacier volume. S5h, j, l). Nature Communications (Nat Commun) https://doi.org/10.1016/B978-0-12-821575-3.00009-8. 5). Nat Commun 13, 409 (2022). However, many glacierized regions in the world present different topographical setups, with flatter glaciers, commonly referred to as ice caps, covering the underlying terrain39. Earth Planet. Despite their limitations, temperature-index models, owing to their simplicity and parsimonious data requirements, have been widely used for large-scale glacier projections7,8. Therefore, linear MB models present more limitations for projections of ice caps, showing a tendency to negative MB biases. Glaciers are experiencing important changes throughout the world as a consequence of anthropogenic climate change1. Nonlinear deep learning response and linear Lasso response to a Cumulative positive degree days (CPDD) anomalies, b winter snowfall, and c summer snowfall. (Springer, New York, 2009). These different behaviours and resulting biases can potentially induce important consequences in long-term glacier evolution projections. Conf. Gabbi, J., Carenzo, M., Pellicciotti, F., Bauder, A. 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. Nisqually Glacier - glaciers.pdx.edu CAS 1 and S1). Vincent, C. et al. Nature 577, 364369 (2020). 0.5) than lower values typical from ice34. A consensus estimate for the ice thickness distribution of all glaciers on Earth. Indeed, the projected 21st century warming will lead to increasing incoming longwave radiation and turbulent fluxes, with no marked future trends in the evolution of shortwave radiation37. Model Dev. Water resources provided by glaciers sustain around 10% of the worlds population living near mountains and the contiguous plains4, depending on them for agriculture, hydropower generation5, industry or domestic use. Climate Change Indicators: Glaciers | US EPA The model output data generated in this study have been deposited in netCDF and CSV format in a Zenodo repository under accession code Creative Commons Attribution 4.0 International. Earths Future 5, 418435 (2017). CAS on various mass balance and radiation components) are opening the door for updated and better constrained projections. Tom R. Andersson, J. Scott Hosking, Emily Shuckburgh, Shfaqat A. Khan, Anders A. Bjrk, Toni Schenk, Romain Hugonnet, Robert McNabb, Andreas Kb, Atanu Bhattacharya, Tobias Bolch, Tandong Yao, Christian Sommer, Philipp Malz, Matthias H. Braun, Romain Millan, Jrmie Mouginot, Mathieu Morlighem, Matthias H. Braun, Philipp Malz, Thorsten C. Seehaus, Nature Communications Future high-mountain hydrology: a new parameterization of glacier retreat. & Zumbhl, H. J. Glaciers and ice caps are experiencing strong mass losses worldwide, challenging water availability, hydropower generation, and ecosystems. Grenoble Alpes, CNRS, G-INP, Laboratoire Jean Kuntzmann, Grenoble, France, You can also search for this author in Explore awards | National Oceanic and Atmospheric Administration A small ablation increase may cause . The first main difference is related to the climate data used to force the models. In this study, we demonstrated the advantages of using deep learning to model glacier MB at regional scales, both in terms of variance and bias. The Cryosphere 13, 11251146 (2019). A NASA-led, international study finds Asia's high mountain glaciers are flowing more slowly in response to widespread ice loss, affecting freshwater availability downstream in India, Pakistan and China. GloGEMflow10 is a state-of-the-art global glacier evolution model used in a wide range of studies, including the second phase of GlacierMIP7,8. Analysis of a 24-Year photographic record of Nisqually glacier, Mount Climate variations change a glacier's mass balance by affecting ablation and accumulation amounts. The Nature of Kinematic Waves in Glaciers and their Application to Get the most important science stories of the day, free in your inbox. We perform, to the best of our knowledge, the first-ever deep learning (i.e. This means that these flatter ice bodies, under a warming climate, will be subject to higher temperatures than their steeper counterparts. contributed to the climate analyses. Nature 575, 341344 (2019). By unravelling nonlinear relationships between climate and glacier MB, we have demonstrated the limitations of linear statistical MB models to represent extreme MB rates in long-term projections. 4 vs.S5). See how Mount Rainier glaciers have vanished over time, with this eye 5). 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. A similar trend is under way. 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. You are using a browser version with limited support for CSS. Large glaciers and glaciers flowing slowly down shallow slopes respond more sluggishly to short-term climate changes, as might be expected. Pellicciotti, F. et al. Relatively minor climate changes during the Little Ice Age (A.D. 1200-1850) impart significant glacial responses. 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. We previously demonstrated that this period is long enough to represent the secular trend of glacier dynamics in the region31. The increase in glacier altitude also causes the solid to liquid precipitation ratio to remain relatively constant. 2013). The nonlinearities present in the simulated annual glacier-wide MB values were assessed by running two different glacier simulations with two different MB models. The authors declare no competing interests. Nonetheless, a better understanding of the underlying processes guiding these nonlinear behaviours at large geographical scales is needed. Res. & Funk, M. A comparison of empirical and physically based glacier surface melt models for long-term simulations of glacier response. 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 rapid glacier retreat is already having an environmental impact on natural hazards20, mountain ecosystems21, and biodiversity6. The 29 RCP-GCM-RCM combinations available, hereafter named climate members, are representative of future climate trajectories with different concentration levels of greenhouse gases (TableS1). 1). Both DEMs were resampled and aligned at a common spatial resolution of 25m. For each glacier, an individual parameterized function was computed representing the differences in glacier surface elevation with respect to the glaciers altitude within the 19792011 period. Overall, the evolving glaciers are expected to undergo rather stable climate conditions under RCP 4.5, but increasingly higher temperatures and rainfall under RCP 8.5 (Fig. Article 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. and JavaScript. 799904) and from the Fonds de la Recherche Scientifique FNRS (postdoctoral grant charg de recherches). In summary, the linear approximations used by the Lasso manage to correctly fit the main cluster of average values but perform poorly for extreme values31. 60, 11401154 (2014). P. Kennard, J. Huss, M., Funk, M. & Ohmura, A. Glaciers with the greatest degree of seasonality in their flow behavior, such as Nisqually and Shoestring glaciers, responded most rapidly. 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. 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. Durand, Y. et al. 10, 42574283 (2017). 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. 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. performed simulations with another glacier model, provided results for comparison, and contributed to the glaciological analyses. 47 (2020). The smallest best performing architecture was used, in order to find a good balance between predictive power, speed, and extrapolation outside the training data. Since in ALPGM the climate forcing of glaciers is extracted at the mean glacier altitude, we do not expect these altitude differences to drive important MB differences between models. 2a and S3). All climate anomalies are computed with respect to the 19672015 mean values. Another source of discrepancy between both models comes from the different MB data used to calibrate or train the MB models. In order to investigate the effects of MB nonlinearities on ice caps, we performed the same type of comparison between simulations, but the glacier geometry update module described in the Glacier geometry evolution section was deactivated. S5cf), except for the largest glaciers (e.g. energy balance), with differences increasing when the conditions considerably differ from the calibration period33. These results revealed that the main uncertainties on glacier simulations arise from the initial ice thickness used to initialize the model. J. Glaciol. (2019) https://doi.org/10.18750/MASSBALANCE.2019.R2019. Appl. On Mount Rainier, elevation surveys of Nisqually Glacier are regularly made to determine changes in the elevation of the surface. Contrasting glacier responses to recent climate change in high-mountain The main uncertainties in future glacier estimates stem from future climate projections and levels of greenhouse gas emissions (differences between RCPs, GCMs, and RCMs), whose relative importance progressively increases throughout the 21st century. Scand. By monitoring the change in size of glaciers around the world, scientists can learn about global climate change. 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. Nisqually Glacier in Mount Rainier National Park, Wash., covers 2.5 square miles (6.5 square kilometers) (1961) and extends from an altitude of about 14,300 feet (4,400 meters) near the top of Mount Rainier down to 4,700 feet (1,400 meters), in a horizontal distance of 4.1 miles (6.6 kilometers). 3c). S6). 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. Maussion, F. et al. J. Clim. CPDD, winter snowfall or summer snowfall) was modified for all glaciers and years. Then, we ran multiple simulations for this same period by altering the initial ice thickness by 30% and the glacier geometry update parametrizations by 10%, according to the estimated uncertainties of each of the two methods31. J. Hosp. Ice-surface altitude changes of as much as 25 meters occurred between 1944 and 1955. Glacier variations in response to climate change from 1972 to 2007 in 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. Google Scholar. Each one of these cross-validations served to evaluate the model performance for the spatial, temporal and both dimensions, respectively. By Carol Rasmussen,NASA's Earth Science News Team.
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