nisqually glacier response to climate change
Earth Sci. The Karakoram and the Himalayan mountain range accommodate a large number of glaciers and are the major source of several perennial rivers downstream. A knowledge of the areas once occupied by mountain glaciers reveals at least part of the past behavior of these glaciers. This means that these flatter ice bodies, under a warming climate, will be subject to higher temperatures than their steeper counterparts. Using this function, the glacier-specific ice thickness and the DEM are updated every year, adjusting the 3D geometry of each glacier. Our synthetic experiment does not account for glacier surface area shrinking either, which might have an impact on the glacier-wide MB signal. Despite marked differences among regions, the generalized retreat of glaciers is expected to have major environmental and social impacts2,3. 1). 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. Z. et al. Annu. April 17, 2019. 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. energy balance), with differences increasing when the conditions considerably differ from the calibration period33. 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. S4). 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 ). A well-established parametrization based on empirical functions50 was used in order to redistribute the annually simulated glacier-wide mass changes over each glacier. 4 ). Roe, G. H. Orographic precipitation. Across the globe, glaciers are decreasing in volume and number in response to climate change. 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. How Will Melting Glaciers Affect Streamflow? - Eos Predicting future glacier evolution is of paramount importance in order to correctly anticipate and mitigate the resulting environmental and social impacts. 49, 26652683 (2017). ADS 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. Rveillet, M. et al. Planet. All values correspond to ensemble means under RCP 4.5. Together with recent findings by another study41 highlighting the increased uncertainties in ice thickness distribution estimates of ice caps compared to mountain glaciers, our results raise further awareness on the important uncertainties in glacier projections for ice caps. However, to further investigate these findings, experiments designed more towards ice caps, and including crucial mechanisms such as ice-ocean interactions and thermodynamics, should be used for this purpose. J. Glaciol. 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). 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. 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. 3). The mountain has three major peaks: Liberty Cap, Point Success, and Columbia Crest (the latter is the summit, located on the rim of the caldera). Hydrol. Roberts, D. R. et al. Get the most important science stories of the day, free in your inbox. Hock, R. & Huss, M. Glaciers and climate change. Carlson, B. As previously mentioned, here these differences are computed at regional level for a wide variety of glaciers. Millan, R., Mouginot, J., Rabatel, A., & Morlighem, M. Ice velocity and thickness of the worlds glaciers. Nonlinear sensitivity of glacier mass balance to future climate change unveiled by deep learning, https://doi.org/10.1038/s41467-022-28033-0. S7). Multiple copies of this dataset were created, and for each individual copy a single predictor (i.e. 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. Arch. The new research suggests that the world's glaciers are disappearing more quickly than scientists previously estimated, and they . Contrasting glacier responses to recent climate change in high-mountain 5). A small ablation increase may cause . J. Hydrol. 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. A He uniform initialization45 was used for the network parameters. Geosci. 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. You are using a browser version with limited support for CSS. In many aspects, it might be too optimistic, as many ice caps will have a negative impact on MB through thinning, bringing their mean surface elevation to lower altitudes, thus further warming their perceived climate. Article Researchers analyzed almost 2 million satellite images of the glaciers and found that 94 . 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. 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. Several differences are present between ALPGM, the model used in this study, and GloGEMflow (TableS2), which hinder a direct meaningful comparison between both. 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. Additionally, glacier surface area was found to be a minor predictor in our MB models31. 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. "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. These are among the cascading effects linked to glacier loss which impact ecosystems and . Hugonnet, R. et al. CAS We ran glacier evolution projections for both the deep learning and Lasso MB models, but we kept the glacier geometry constant, thus preserving the glacier centroid where the climate data is computed constant through time. Studies have warned about the use of temperature-index models for snow and ice projections under climate change for decades34,35,36. The initial glacier ice thickness data for the year 2003 also differs slightly between both models. This approach is known as a cross-validation ensemble49. ISSN 2041-1723 (online). Sci. With a secondary role, glacier model uncertainty decreases over time, but it represents the greatest source of uncertainty until the middle of the century8. The authors declare no competing interests. The application of a non-linear back-propagation neural network to study the mass balance of Grosse Aletschgletscher, Switzerland. This synthetic setup allowed us to reproduce the climatic conditions to be undergone by most ice caps, with their mean surface altitude hardly evolving through time. The Elements of Statistical Learning. 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. 3c), which is directly linked to summer air temperatures and has a strong influence on surface albedo. Clim. (Zenodo, 2020). J. Glaciol. 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. Geophys. S5cf), except for the largest glaciers (e.g. Comput. Steiner, D., Walter, A. 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. 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. Since these flatter glaciers are more likely to go through extreme negative MB rates, nonlinear responses to future warming play a more important role, producing cumulative MB differences of up to 20% by the end of the century (Fig. Particularly in Asia, water demand exceeds supply due to rapid population growth, with glacier . Our results confirm an over-sensitivity of temperature-index models, often used by large-scale studies, to future warming. Alternatively, the Lasso MB model displayed an RMSE of 0.85m.w.e. Interestingly, this matches the nonlinear, less sensitive response to summer snowfall in the ablation season of our deep learning model (Fig. Nonlinear sensitivity of glacier mass balance to future climate change unveiled by deep learning. Model Dev. 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. From this behavior, inferences of past climate can be drawn. 65, 453467 (2019). J. Geophys. S10). As Arctic warms, Canada's glaciers playing major role in sea - CBC This ensures that the model is capable of reproducing MB rates for unseen glaciers and years. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate. Bolibar, J., Rabatel, A., Gouttevin, I. On Mount Rainier, elevation surveys of Nisqually Glacier are regularly made to determine changes in the elevation of the surface. Nonetheless, to represent the glacier mass balance, the vast majority of large-scale glacier evolution models relies on temperature-index models. In Climate Change 157176 (Elsevier, 2021). 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. 12, 909931 (2019). J. Glaciol. & Funk, M. A comparison of empirical and physically based glacier surface melt models for long-term simulations of glacier response. S5 and S6). 0.5) than lower values typical from ice34. IPCC. S8 and Fig. Because of easy access and prominent location the glacier has been studied since the mid 1850's. In 1857, Lt. August Kautz crossed Nisqually Glacier during an attempt to climb the summit.
