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Maps of glacier area in western Canada have recently been generated for 1985 and 2005 (Bolch et al., 2010), providing the first complete inventory of glacier cover in Alberta and British Columbia. Western Canada lost about 11% of its glacier area over this period, with area loss exceeding 20% on the eastern slopes of the Canadian Rockies. Glacier a...
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... However, some studies have pointed out that this type of locally varying regression parameter may only apply to larger glacier groups with accurate profiles and not to individual glaciers [20]. Some studies have reported uncertainties of around 50-60% [19,69]. Table 4. Previous studies' estimates of ice volume, maximum, and average ice thickness: RH10 and In terms of estimated ice volume, as shown in Table 4, the ice volume estimated by the ES is close to the ice volume estimated by the OGGM (0.27 km 3 ) but is 20.66% lower than F19 and 31.83% ...
... However, some studies have pointed out that this type of locally varying regression parameter may only apply to larger glacier groups with accurate profiles and not to individual glaciers [20]. Some studies have reported uncertainties of around 50-60% [19,69]. The differences in the volumes obtained by the five methods used to construct the ES can also reach 30%. ...
As a heavily glaciated region, the Eastern Pamir plays a crucial role in regional water supply. However, considerable ambiguity surrounds the distribution of glacier ice thickness and the details of ice volume. Accurate data at the local scale are largely insufficient. In this study, ground-penetrating radar (GPR) was applied to assess the ice thickness at Muztagh Glacier No.16 (MG16) in Muztagh Ata, Eastern Pamir, for the first time, detailing findings from four distinct profiles, bridging the gap in regional measurements. We utilized a total of five different methods based on basic shear stress, surface velocity, and mass conservation, aimed at accurately delineating the ice volume and distribution for MG16. Verification was conducted using measured data, and an aggregated model outcome provided a unified view of ice distribution. The different models showed good agreement with the measurements, but there were differences in the unmeasured areas. The composite findings indicated the maximum ice thickness of MG16 stands at 115.87 ± 4.55 m, with an ice volume calculated at 0.27 ± 0.04 km³. This result is relatively low compared to the findings of other studies, which lies in the fact that the GPR measurements somewhat constrain the model. However, the model parameters remain the primary source of uncertainty. The results from this study can be used to enhance water resource assessments for future glacier change models.
... Given their relatively small size, these glaciers are therefore particularly sensitive to changes in temperature and atmospheric conditions (Menounos et al., 2019;Rounce et al., 2023). In part because of this, glacierized alpine regions of the Canadian Rocky Mountains have long been a point of scientific interest and inquiry with research generally focused on the rapid diminishment of the icefields and outlet glaciers there (e.g., Marshall et al., 2011;Tennant et al., 2012). For example, between 1919 and 2009, the mean area change of all outlet glaciers stemming from the Columbia Icefield was modeled at −2.4 km 2 (or −34%; Tennant & Menounos, 2013), with corresponding studies highlighting large-scale glacier termini thinning and recession during this century (see also Figure 1 for a visual of Athabasca Glacier in 1918 andOmmanney, 2002;Rippin et al., 2020;Tennant & Menounos, 2013). ...
... On the eastern slopes, glacier volume is projected to decline 80%-90% by 2100 with subsequent changes to the volume and timing of meltwater and biogeochemical inputs into downstream rivers (Clarke et al., 2015;Radić et al., 2014). It is no surprise, then, that the glaciers on the eastern slopes have been shown to be past their tipping point (Marshall et al., 2011). ...
... The same study also noted strong positive correlations between the total glacierized area of a watershed and the glacial melt contributions to river flow across the eastern slopes of the Canadian Rocky Mountains (Comeau et al., 2009). This correlation supports the relative decrease in summer discharge peaks (driven by glacial melt) compared to spring discharge peaks (driven by snow melt) with increasing distance downstream observed along each study river (Figure 4; also see Marshall, 2014), and suggested that the proportional glacier meltwater outputs from SR-AR and NSR watersheds, where nearly 77% of Alberta's glacierized area is located (Marshall & White, 2010), are likely far greater than glacier meltwater outputs from the less glacierized BR watershed (Comeau et al., 2009;Demuth & Pietroniro, 2003;Marshall & White, 2010;Marshall et al., 2011). ...
Climate change is driving the loss of alpine glaciers globally, yet investigations about the water quality of rivers stemming from them are few. Here we provide an overview assessment of a biogeochemical data set containing 200+ parameters that we collected between 2019 and 2021 from the headwaters of three such rivers (Sunwapta‐Athabasca, North Saskatchewan, and Bow) which originate from the glacierized eastern slopes of the Canadian Rocky Mountains. We used regional hydrometric data sets to accurately model discharge at our 14 sampling sites. We created a Local Meteoric Water Line (LMWL) using riverine water isotope signatures and compared it to collected regional rain, snow, and glacial ice signatures. Principal component analyses of river physicochemical measures revealed distance from glacier explained more data variability than other spatiotemporal factors (i.e., season, year, or river). Discharge, chemical concentrations, and watershed areas were then used to model site‐specific open water season yields for 25 parameters. Chemical yields followed what would generally be expected along river continuums from glacierized to montane altitudinal life zones, with landscape characteristics driving chemical sources and sinks. For instance, particulate chemical yields were generally highest near source glaciers with proglacial lakes acting as settling ponds, whereas most dissolved yields varied by parameter and site. As these headwaters continue to evolve with glacier mass loss, the data set and analyses presented here can be used as a contemporary baseline to mark future change against. Further, following this initial assessment of our data set, we encourage others to mine it for additional biogeochemical studies.
... Stahl and Moore (2006) address this by considering glacier contributions to streamflow as a function of glacierized area. For the Bow River in Calgary, for instance, glacier mass loss in recent decades accounts for �2% of the annual water supply (Marshall et al. 2011;Bash and Marshall 2014), which seems negligible but reflects the fact that only 0.3% of the basin is currently glacierized. The North Saskatchewan River in Edmonton has greater glacier area in its headwaters and is correspondingly more glacier-fed (�3%) than the Bow River in Calgary (Marshall et al. 2011). ...
... For the Bow River in Calgary, for instance, glacier mass loss in recent decades accounts for �2% of the annual water supply (Marshall et al. 2011;Bash and Marshall 2014), which seems negligible but reflects the fact that only 0.3% of the basin is currently glacierized. The North Saskatchewan River in Edmonton has greater glacier area in its headwaters and is correspondingly more glacier-fed (�3%) than the Bow River in Calgary (Marshall et al. 2011). Glacial runoff can be normalized by the glacier cover to enable better intercomparison of sites, and Moore et al. (2020) find this relation to be close to linear. ...
... In the future, climate change will continue these trends, making heatwaves longer, more frequent, and more intense (Meehl & Claudia, 2004). At the same time, climate change has already reduced glacier area and volume globally (Hugonnet et al., 2021;Zemp et al., 2015), as well as in western Canada (Bolch et al., 2010), trends of deglaciation that will continue under climate change (Clarke et al., 2015;Marshall et al., 2011;Radić et al., 2014). The loss of glacier ice will lead to both reduced summer streamflow and increased interannual variability of 3 of 20 summer streamflow in glacierized basins. ...
... Basin glacier coverage is unchanged in our simulations of streamflow in the warmer scenario, since the model only considers temperature, precipitation, and streamflow data. In reality, it is projected that a majority of glacier ice will be lost in Western Canada by the end of the century even under moderate levels of climate change (Clarke et al., 2015;Marshall et al., 2011). As such, our warm scenario simulations should be interpreted as the sensitivity of the glacier coverage classes to annual temperatures, and not as future projections of individual basins. ...
In addition to having far‐reaching impacts on human health, agriculture, wildfires, ecosystems, and infrastructure, heatwaves control streamflow through the melting of seasonal snow and glacier ice. Despite their importance, there is limited understanding of how heatwaves modify streamflow at regional scales, how these impacts vary by heatwave timing and duration, and how glaciers control the streamflow response. Here, we use a deep learning hydrological model, which has previously been trained, evaluated, and interpreted in southwestern Canada, to simulate the streamflow response to heatwaves at 111 basins in the region. The model, driven by gridded ERA5 reanalysis temperature and precipitation data from 1979 to 2015, is forced by synthetic heatwave conditions that vary in their duration and onset throughout the year. We consider how the streamflow response to heatwaves is sensitive to annual temperatures by adding spatially and temporally uniform warming of 2°C across the study region, under the assumption that the underlying hydrological system behavior remains unchanged. We find that heatwaves, particularly in spring and summer, induce an initial streamflow surplus followed by a streamflow deficit, relative to the non‐heatwave case. In summer, glacier contributions to streamflow partially compensate for streamflow deficits that arise from heatwaves earlier in the melt season. In the scenario with 2°C warmer annual temperatures, heatwaves induce a lesser streamflow response in spring when the seasonal streamflow is most increased due to the advancing freshet. Our findings demonstrate how glaciers buffer the impacts of heatwaves on streamflow, but this buffering effect is expected to diminish as glaciers retreat.
... Clarke et al. (2015), in a regional estimate of glacier retreat to 2100 for Western Canada, found the glaciers of the southern Canadian Rockies will retreat by up to 95% from their 2005 extent, and cause a strong decrease in glacier-fed flow. Marshall et al. (2011) provided an estimate of future glacier contribution to streamflow on the eastern side of the Canadian Rockies using a statistical analysis of past conditions and found a near disappearance of glacier volume, and a strong reduction in late summer flows. Recently, Chernos et al. (2020) found a decrease of up to 58% in late summer streamflow by 2100 for the nearby Upper Athabasca River basin. ...
... The remaining ice cover is based on a simulation of regional deglaciation in the Canadian Rockies by Clarke et al. (2015) who found a range of 0%-15% of the 2005 ice coverage in the Canadian Rockies by 2085 under RCP8.5. This is similar to Marshall et al. (2011), who suggested that by 2100, only 3% of the 2005 ice coverage would be left in the North Saskatchewan basin under scenario A1B. ...
Shifting precipitation patterns, a warming climate, changing snow dynamics and retreating glaciers are occurring simultaneously in glacierized mountain headwaters. To predict future hydrological behaviour in an exemplar glacierized basin, a spatially distributed, physically based cold regions process hydrological model including on and off‐glacier process representations was applied to the Peyto Glacier Research Basin in the Canadian Rockies. The model was forced with bias‐corrected outputs from a high‐resolution Weather and Research Forecasting (WRF‐PGW) atmospheric simulation for 2000‐2015, and under pseudo‐global warming for 2085‐2100 under a business‐as‐usual climate change scenario. The simulations show that the end‐of‐century increase in precipitation nearly compensates for the decreased ice melt associated with almost complete deglaciation, resulting in a decrease in annual streamflow of 7 %. However, the timing of streamflow advances drastically, with peak flow shifting from July to June, and August streamflow dropping by 68 %. To examine the sensitivity of future hydrology to possible future drainage basin biophysical attributes, the end‐of‐century simulations were run under a range of initial conditions and parameters and showed the highest sensitivity to initial ice volume and surface water storage capacity. This comprehensive examination suggests that hydrological compensation between declining icemelt and increasing rainfall and snowmelt runoff as well as between deglaciation and increasing basin depressional storage capacity play important roles in determining future streamflow in a rapidly deglaciating high‐mountain environment. Conversely, afforestation and soil development had relatively smaller impacts on future hydrology.
... The fraction of the precipitation as snowfall declines and rainfall ratio increases with the warming air temperatures (Knowles et al., 2006;Shook and Pomeroy, 2012), and this leads to decreases in seasonal snow accumulation (Fang and Pomeroy, 2020;Lapp et al., 2005) and earlier spring snowmelt runoff (Fang and Pomeroy, 2020;Rood et al., 2008) in the Canadian Rockies. Warming climate can cause changes to glacier contributions to streamflow in the southern Canadian Cordillera from glacier retreat (DeBeer et al., 2016;Munro, 2005), resulting in a shift in glacier-fed river flow regimes (Demuth et al., 2008;Marshall et al., 2011). Many headwater rivers draining the Canadian Rockies eastern slopes over the 20th century have shown significant declining trends in annual flow volume (Burn et al., 2004), flood peak and volume (Whitfield and Pomeroy, 2016), and summer flow (Rood et al., 2008). ...
... Mountains are also critical regions for snowmelt-driven streamflow generation and groundwater recharge (Hayashi 2020), which flows through the subsurface, discharging to streams at lower elevations (Markovich et al. 2019;Campbell and Ryan 2021). Alpine glaciers serve as an additional source of water supply once seasonal snow has melted (Comeau, Pietroniro, and Demuth 2009;Marshall et al. 2011). Foothills and plains environments are characterized by lower precipitation, higher evapotranspiration, and shorter winters relative to mountain environments (Raddatz and Shaykewich 1998;Newton, Farjad, and Orwin 2021). ...
Geographic inequalities in water distribution can lead to relatively small regions driving or buffering changes in water availability in major watersheds. This research provides a baseline quantification of water distribution in Alberta, Canada, and evaluates changes in water yield, streamflow timing, and climate from 1976 to 2015. Annual water yields for 77 contributing watershed areas were calculated and assessed for trends, and 45 unregulated watersheds were evaluated for changes in key streamflow timing metrics. Mountain headwaters supply 22–38% of annual flow of major rivers, while plains watersheds provide relatively low annual yield. Annual yield and precipitation decreases dominated northern watersheds, with increases in southern watersheds, and mixed trends in central watersheds. Later spring freshet timing and earlier onset of the low flow season were detected for most watersheds, leading to more water over a shorter duration when paired with increasing yield, and water losses in late summer-autumn when paired with decreasing yield. Yield and flow timing metrics are strongly related to precipitation with temperature as a secondary driver, except freshet timing, which is driven by spring temperature. This study provides comprehensive information about geographic drivers of changing water distribution and quantifies the disparity between regions of water surplus and deficit.
... Western Canadian glaciers lost considerable mass over the last several decades with increasing rates in the period since the mid-1990s (Larsen and others, 2007;Arendt and others, 2009;Zemp and others, 2015;Demuth, 2018;Hugonnet and others, 2021). Menounos and others (2019) observed a fourfold increase in mass budget between 2000-2009 and 2009-2018 for the western North American glaciers in response to changes in temperature, precipitation and storm tracks (Walters and Meier, 1989;Demuth and Keller, 2006;Shea and Marshall, 2007;Demuth and others, 2008;Marshall and others, 2011;Menounos and others, 2019). Glacier mass loss in western Canada is projected to increase in the coming decades due to increases in annual and seasonal mean temperature, and reduced snowfall amounts (Schiefer and others, 2007;Clarke and others, 2015;Vincent and others, 2018;Hock and others, 2019b). ...
Reliable, long-term records of glacier mass change are invaluable to the glaciological and climate-change communities and used to assess the importance of glacier wastage on streamflow. Here we evaluate the in-situ observations of glacier mass change for Place (1982-2020) and Peyto glaciers (1983-2020) in western Canada. We use geodetic mass balance to calibrate a physically-based mass-balance model coupled with an ice dynamics routine. We find large discrepancies between the glaciological and geodetic records for the periods 1987-1993 (Place) and 2001-2006 (Peyto). Over the period of observations, the exclusion of ice dynamics in the model increased simulated cumulative mass change by ∼10.6 (24%) and 7.1 (21%) m w.e. for Place and Peyto glacier, respectively. Cumulative mass loss using geodetic, modelled and glaciological approaches are respectively − 30.5 ± 4.5, − 32.0 ± 3.6, − 29.7 ± 3.6 m w.e. for Peyto Glacier (1982-2017) and − 45.9 ± 5.2, − 43.1 ± 3.1, − 38.4 ± 5.1 m w.e. for Place Glacier (1981-2019). Based on discrepancies noted in the mass-balance records for certain decades (e.g. 1990s), we caution the community if these data are to be used for hydrological model development.
... Data sources for elevation, land use and soils are shown in table S1. Glacier cover is considered based on the Randolph Glacier Inventory (RGI 2017), and glacier thickness was estimated by slope inversion and uniform shear stress of 10 5 Pa (Marshall et al 2011). Glacier extent was kept constant throughout the simulation periods as we estimated glacier contributions to floods to be negligible (see section 2). ...
The densely populated delta of the three river systems of the Ganges, Brahmaputra and Meghna is highly prone to floods. Potential climate change-related increases in flood intensity are therefore of major societal concern as more than 40 million people live in flood-prone areas in downstream Bangladesh. Here we report on new flood projections using a hydrological model forced by bias-adjusted ensembles of the latest-generation global climate models of CMIP6 (SSP5-8.5/SSP1-2.6) in comparison to CMIP5 (RCP8.5/RCP2.6). Results suggest increases in peak flow magnitude of 36% (16%) on average under SSP5-8.5 (SSP1-2.6), compared to 60% (17%) under RCP8.5 (RCP2.6) by 2070-2099 relative to 1971-2000. Under RCP8.5/SSP5-8.5 (2070-2099), the largest increase in flood risk is projected for the Ganges watershed, where higher flood peaks become the “new norm” as early as mid-2030 implying a relatively short time window for adaptation. In the Brahmaputra and Meghna rivers, the climate impact signal on peak flow emerges after 2070 (CMIP5 and CMIP6 projections). Flood peak synchronization, when annual peak flow occurs simultaneously at (at least) two rivers leading to large flooding events within Bangladesh, show a consistent increase under both projections. While the variability across the ensemble remains high, the increases in flood magnitude are robust in the study basins. Our findings emphasize the need of stringent climate mitigation policies to reduce the climate change impact on peak flows (as presented using SSP1-2.6/RCP2.6) and to subsequently minimize adverse socioeconomic impacts and adaptation costs. Considering Bangladesh's high overall vulnerability to climate change and its downstream location, synergies between climate change adaptation and mitigation and transboundary cooperation will need to be strengthened to improve overall climate resilience and achieve sustainable development.
... The Columbia Icefield is of crucial importance to the region's water budget, as it feeds three different continental-scale watersheds flowing towards the Arctic, Pacific and Atlantic oceans (Fig. 1a). The main and largest outlet glaciers are located east of the icefield (Saskatchewan and Athabasca Glacier), draining ∼ 60 % of the eastern Columbia Icefield to the North Saskatchewan River (Hudson and Atlantic) and the Sunwapta-Athabasca River (Arctic) (Marshall et al., 2011). Tennant and Menounos (2013) used historical aerial photographs and satellite images to reconstruct the extent and volume changes in the Columbia Icefield. ...
Glacier mass balance models are needed at sites with scarce long-term observations to reconstruct past glacier mass balance and assess its sensitivity to future climate change. In this study, North American Regional Reanalysis (NARR) data were used to force a physically based, distributed glacier mass balance model of Saskatchewan Glacier for the historical period 1979–2016 and assess its sensitivity to climate change. A 2-year record (2014–2016) from an on-glacier automatic weather station (AWS) and historical precipitation records from nearby permanent weather stations were used to downscale air temperature, relative humidity, wind speed, incoming solar radiation and precipitation from the NARR to the station sites. The model was run with fixed (1979, 2010) and time-varying (dynamic) geometry using a multitemporal digital elevation model dataset. The model showed a good performance against recent (2012–2016) direct glaciological mass balance observations as well as with cumulative geodetic mass balance estimates. The simulated mass balance was not very sensitive to the NARR spatial interpolation method, as long as station data were used for bias correction. The simulated mass balance was however sensitive to the biases in NARR precipitation and air temperature, as well as to the prescribed precipitation lapse rate and ice aerodynamic roughness lengths, showing the importance of constraining these two parameters with ancillary data. The glacier-wide simulated energy balance regime showed a large contribution (57 %) of turbulent (sensible and latent) heat fluxes to melting in summer, higher than typical mid-latitude glaciers in continental climates, which reflects the local humid “icefield weather” of the Columbia Icefield. The static mass balance sensitivity to climate was assessed for prescribed changes in regional mean air temperature between 0 and 7 ∘C and precipitation between −20 % and +20 %, which comprise the spread of ensemble Representative Concentration Pathway (RCP) climate scenarios for the mid (2041–2070) and late (2071–2100) 21st century. The climate sensitivity experiments showed that future changes in precipitation would have a small impact on glacier mass balance, while the temperature sensitivity increases with warming, from −0.65 to −0.93 m w.e. a−1 ∘C−1. The mass balance response to warming was driven by a positive albedo feedback (44 %), followed by direct atmospheric warming impacts (24 %), a positive air humidity feedback (22 %) and a positive precipitation phase feedback (10 %). Our study underlines the key role of albedo and air humidity in modulating the response of winter-accumulation type mountain glaciers and upland icefield-outlet glacier settings to climate.
