Res. Six, D. & Vincent, C. Sensitivity of mass balance and equilibrium-line altitude to climate change in the French Alps. Climate Change 2013: The Physical Science Basis. Tests were performed distributing the CPDD anomalies equally among all months of the year with very similar results. 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. 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. A He uniform initialization45 was used for the network parameters. In recent years, shrinking glaciers have contributed to about 30% of global sea level rise 1. An accurate prediction of future glacier evolution will be crucial to successfully adapt socioeconomic models and preserve biodiversity. This means that these flatter ice bodies, under a warming climate, will be subject to higher temperatures than their steeper counterparts. 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. In order to overcome these differences, some adaptations were performed to the GloGEMflow output, accompanied with some hypotheses to ensure a realistic comparison. 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. The Multitrophic Effects of Climate Change and Glacier Retreat - JSTOR "Their numbers have gone from regularly exceeding 50,000 adult salmon in the Nisqually to about 5,000 last year." The Nisqually River near its glacial origins. 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. Robinson, C. T., Thompson, C. & Freestone, M. Ecosystem development of streams lengthened by rapid glacial recession. (2019) https://doi.org/10.18750/MASSBALANCE.2019.R2019. To interactively describe to response of glaciers to climate change, a glacier parameterization scheme has been developed and implemented into the regional climate model REMO. 4 vs.S5). Differences in projected glacier changes become more pronounced from the second half of the century, when about half of the initial 2015 ice volume has already been lost independent of the considered scenario. https://doi.org/10.1038/s41467-022-28033-0, DOI: https://doi.org/10.1038/s41467-022-28033-0. 2a). J. Glaciol. Nisqually Glacier is the lengthiest of any made in North America. CAS The lower fraction of variance explained by linear models is present under all climate scenarios. 0.78m.w.e. These bulges, called kinematic waves, form when higher than normal snowfall builds up in the accumulation area of the glacier (c). PubMedGoogle Scholar. By submitting a comment you agree to abide by our Terms and Community Guidelines. J. Appl. Hock, R. et al. Park, and S. Beason. 3c). C.G. Our synthetic experiment does not account for glacier surface area shrinking either, which might have an impact on the glacier-wide MB signal. The original ice thickness estimates of the methods used by both models are different10,32, and for ALPGM we performed some additional modifications to the two largest glaciers in the French Alps (see Glacier geometry evolution for details). However, many glacierized regions in the world present different topographical setups, with flatter glaciers, commonly referred to as ice caps, covering the underlying terrain39. 15 - Response of glaciers to climate change - Cambridge Core 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. 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. 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). Despite their limitations, temperature-index models, owing to their simplicity and parsimonious data requirements, have been widely used for large-scale glacier projections7,8. Google Scholar. How Will Melting Glaciers Affect Streamflow? - Eos Glacier-wide MB is simulated annually for individual glaciers using deep learning (i.e. 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. 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. Front. 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. 49, 26652683 (2017). This synthetic experiment is an approximation of what might occur in other glacierized regions with ice caps. Changes in DDFs with respect to air temperature also strongly depend on albedo, with ice presenting a substantially more nonlinear response than snow. 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. Deep learning captures a nonlinear response of glaciers to air temperature and precipitation, improving the representation of extreme mass balance rates compared to linear statistical and temperature-index models. The Cryosphere 13, 11251146 (2019). Botanical Evidence of the Modern History of Nisqually Glacier - USGS a Projected mean glacier altitude evolution between 2015 and 2100. The increase in glacier altitude also causes the solid to liquid precipitation ratio to remain relatively constant. regularized multilinear regression. The Nisqually Glacier is one of the larger glaciers on the southwestern face of Mount Rainier in the U.S. state of Washington.The glacier is one of the most easily viewed on the mountain, and is accessible from the Paradise visitor facilities in Mount Rainier National Park.The glacier has had periods of advance and retreat since 1850 when it was much more extensive. CPDD, winter snowfall or summer snowfall) was modified for all glaciers and years. At the Edge: Monitoring Glaciers to Watch Global Warming - NASA Rackauckas, C. et al. Pellicciotti, F. et al. The cumulative positive degree days (CPDD), snowfall and rainfall dl, are at the glaciers annually evolving centroids. Limnol. S10). 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. 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. 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. Nonlinear sensitivity of glacier mass balance to future climate change Glaciers on Mount Rainier - USGS These trends explored with energy balance models from the literature correspond to the behaviour captured by our deep learning MB model, with a clearly less sensitive response of glacier-wide MB to extreme climate forcings, particularly in summer (Fig. Explore awards | National Oceanic and Atmospheric Administration 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. Alluvial landscape response to climate change in glacial rivers and the implications to transportation infrastructure. ISSN 2041-1723 (online). He, K., Zhang, X., Ren, S. & Sun, J. Delving Deep into Rectifiers: Surpassing Human-Level Performance on ImageNet Classification. Alternatively, flatter glaciers (i.e. volume13, Articlenumber:409 (2022) 58, 267288 (1996). 3 (2015). Between 1857 and 1979, Nisqually Glacier receded a total of 1,945 meters and advanced a total of 294 meters. Univ. GlacierMIP A model intercomparison of global-scale glacier mass-balance models and projections. Z. et al. Provided by the Springer Nature SharedIt content-sharing initiative. 3b). 4). 1). a1 and an r2 of 0.3531. The source code of the glacier model can be freely accessed in the following repository: https://github.com/JordiBolibar/ALPGM. The first main difference is related to the climate data used to force the models. In Climate Change 157176 (Elsevier, 2021). 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. The authors declare no competing interests. The nonlinearities present in the simulated annual glacier-wide MB values were assessed by running two different glacier simulations with two different MB models. In this study, we investigate the future evolution of glaciers in the French Alps and their nonlinear response to multiple climate scenarios. This modelling approach was described in detail in a previous publication dedicated to the methods, where the ALpine Parameterized Glacier Model (ALPGM43) was presented31. energy balance), with differences increasing when the conditions considerably differ from the calibration period33. The Open Global Glacier Model (OGGM) v1.1. "The Patagonia Icefields are dominated by so-called 'calving' glaciers," Rignot said. 'When the Glaciers Disappear, Those Species Will Go Extinct' Bolibar, J. et al. 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. 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. & Zumbhl, H. J. Zekollari, H., Huss, M. & Farinotti, D. On the Imbalance and Response Time of Glaciers in the European Alps. 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. 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. 5). Res. 33, 645671 (2005). Atmospheres 121, 77107728 (2016). Geophys. Nat. 2) and RCP 8.5 by the end of the century. A similar behaviour is observed when comparing temperature-index models to more complex models (e.g. Landscape response to climate change and its role in infrastructure 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. The Nisqually Glacier, Mount Rainier, Washington, 1857-1979: A summary Marzeion, B. et al. Res. Dyn. Thin lines represent each of the 29 individual member runs, while the thick lines represent the average for a given RCP. The smallest best performing architecture was used, in order to find a good balance between predictive power, speed, and extrapolation outside the training data. Strong Alpine glacier melt in the 1940s due to enhanced solar radiation. J. Hydrol. Geophys. Fr Hydrobiol. The scheme simulates the mass balance as well as changes of the areal . Bolibar, J., Rabatel, A., Gouttevin, I. Remote Sens. (Springer, New York, 2009). 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. A well-established parametrization based on empirical functions50 was used in order to redistribute the annually simulated glacier-wide mass changes over each glacier. Future projections of glacier-wide MB evolution were performed using climate projections from ADAMONT25. 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. The ice thickness data for two of the largest glaciers in the French Alps were modified in order to improve data quality. ICCV (2015) https://doi.org/10.1109/iccv.2015.123. 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.
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