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Page 1: A Slow End: Tracking Glacier Loss on Mount Rainier, Washingtonweb.pdx.edu/~jduh/courses/geog492s14/Projects/01_Mount... · 2014. 6. 9. · We see that the glaciers on Mt. Rainier

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Nisqually-Wilson Glacier Center Line Pro�le

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Glacial ice is the largest reservoir of freshwater on earth, and Mount Rainier is the most heavily glaci-ated peak in the lower 48 states(1). We have heard that climate change is shrinking glaciers, but what does this mean for Mt. Rainier's glaciers during the next 50 or 100 years? Speci�cally, what is the risk of losing the freshwater supply from Mt. Rainier's glaciers?Our investigation includes 3 approaches to analyz-ing glacial recession. Using one of these, a signi�-cant relationship between glacier length and long-term temperature changes, we present a plau-sible future scenario based on moderate climate change(3).

Recession Analysis We applied an existing model developed by Johannes Oerlemans(4) to estimate changes in the length of Mt. Rainier's glaciers based on long-term temperature changes. Oerleman's model comes from his analysis of 48 glaciers around the world receding from 1850 onward. He concludes there is an average of 2 km recession per year for a temperature change of 1 degree K, over a period of 94 years. Based on his detailed results, we used a temperature-based recession factor of 21.10501030 meter per year per degree K in our model.To calculate glacier length, we investigated two alternatives: the length of the minimum bounding rectangle for each glacier polygon and the upstream �ow length from a hydrology analysis. Though both yielded similar results (Pearson correlation co-e�cient = 0.95, p-value = 0.000), the former was chosen as the best �t, as its results were both longer and more consistent with lengths reported in other resources(1,5).This model was applied to historical Nisqually glacier recession data for the period 1868 to 1960 from Mount Rainier National Park (MORA)(6). The observed recession was 1.6km, and the model-predicted recession was 1.5km, which is well within the 15% stated error for the model. We chose this model and applied it to all the glaciers on Mt. Rainier for the periods 2006 to 2050 and 2006 to 2099. Average annual temperatures for each year were acquired from NCAR as point shape�les. Using cokriging, these were combined with the DEM to yield temperature surfaces. Zonal statistics provided the mean temperature for each glacier.This model was further used to estimate when the glaciers on Mt. Rainier might disappear, based on an exponential regression analysis (recession = 4.4706 * temp change^1.6377, R² = 0.9732) to smooth the predicted yearly changes in temperature.

Regression AnalysisWe ran ordinary least squares and exploratory regression analysis with calculated yearly length changes for up to 10 of the glaciers on Mt. Rainier, for most of the years between 1919 and 1991. We also ran the same analyses for the volume changes of 29 glaciers over a 44 year span.The concepts behind this approach came from Nylen’s master’s thesis and Sisson’s 2011 Geology article. Time-based pre-dictor variables included temperatures, precipitation, and carbon dioxide levels. Geomorphological predictor variables included aspect (transformed, then averaged for the glacier), slope (mean), elevation (min, max and mean), length, and area. This analysis did not yield a usable model for predicting length or volume change. However, correlation analysis using this data and the data from the MORA reports(6) indicates there is a signi�cant correlation between glacier change and a few variables, detailed in the table.

ConclusionsGlacier recession can be estimated at a gross level (plus/minus 15%) using changes in temperature and Oerleman's formula, however this is best suited for long periods of time, ideally using smoothed tem-perature data. As exempli�ed by volume analysis, accurate estimation on a year-to-year basis depends on too many factors (recent winter snowfall, temperature/CO2, time above freezing, insolation, and geomorphological attributes and anomalies speci�c to each glacier) to be de�ned by a simpli�ed equa-tion.We see that the glaciers on Mt. Rainier and the freshwater they supply may be largely gone by the end of the 21st century based on the A1B moderate-climate-change scenario(3). Other scenarios o�er more or less dramatic increases in temperature, with end-of-century di�erences around plus or minus 2 de-grees C from the A1B. With Oerlaman's model, this might yield di�erences in glacier recession of plus or minus 4 kilometers.

Data Sources and References: GeoCommunity (geocomm.com) USGS 1970 10m DEM; Puget Sound LiDAR Consortium (pugetsoundlidar.ess.washington.edu) 2011 1m DEM and 16bit Hillshade; National Center for Atmospheric Research (gisclimatechange.ucar.edu/gis-data)(3); Washington State Department of Ecology (ecy.wa.gov/services/gis/data); Department of Commerce, Census Bureau; National Oceanic and Atmospheric Administration (ncdc.noaa.gov/cdo-web and esrl.noaa.gov/gmd/ccgg/trends); Glaciers of the American West (glaciers.us/Downloads)(6); National Snow and Ice Data Center (nsidc.org/data/docs)(5); Nylen, Thomas H., “Spatial and Temporal Variations of Glaciers (1913-1994) on Mt. Rainier and the Relation with Climate Change”, Portland State University Master’s Thesis, 2001; Oerlemans, Johannes, “Quantifying Global Warming from the Retreat of Glaciers”,

Science Magazine, 8 April 1994 (sciencemag.org/content/264/5156/243)(4); Sisson, T.W., “Whole-edi�ce Ice Volume Change A.D. 1970 to 2007/2008 at Mount Rainier, Washington, based on LiDAR surveying”, Geology, July 2011, v. 39, no. 7, p. 639-642 (geology.gsapubs.org)(2); National Park Service (nps.gov/mora/naturescience/glaciers.htm)(1). Special thank you to: Dr. Geo�rey Duh and Dr. Andrew Fountain for your guidance and expertise.

Volume/Thickness AnalysisMonitoring and calculating area and volume on alpine glaciers is fraught with limitations and the possibility for errors. 1986 marked the �rst volume calculations by Driedger and Kennard, estimating 4.42 km3 of snow and ice in 1970 on Mount Rainier using radar and 1970 contour maps(2). Much like Sisson in 2011, we attempted to redraw the areas bounds using the 1m 16bit LiDAR hillshade alone. Because of the di�culty and limited knowledge of glaciology, we only analyzed the 29 named glaciers of the recognized 49 perennial snow/ice �elds that are on Rainier. Straight away, we began to see signi�cant di�erences from the 2011 study. We measured 84.9 km2 of glacier cover, Sisson calculated 93.3 km2 of total perennial snow and ice cover. Utilizing the 3D Analysis toolset in ArcGIS, we calculated a 3D surface area of 94.1 km2 across the same shape�les using the 10m 1970 DEM. We used both the same di�erencing method as Sisson and the 3D Analyst tool “Cut-Fill” to calculate the volume change between the 1970 and 2011 DEMs, maintaining a 10m resolution as opposed to resampling to 100m(2). Both methods resulted in identical output. Ultimately we found a total volume loss of 0.47 km3. Sisson calculated 0.56 km3 across all the same glaciers using the 2008 LiDAR. Despite using the same method, our results are varyingly di�erent across the board. We attribute this random, gross di�erence to our conservatively digitized shape�les. We believe it nearly impossible that such volumetric di�erences could occur over a 3 year span.In spite of these errors, we were still able to visually produce nearly identical visual outputs as Sisson. Using the same data generation as the recession analysis, we were able to visually see variable correlation. The most dramatic is the nearly uniform equilibrium elevation at 2100m.It is our hope that with the increasing use of LiDAR, more precise measurements consisting of shorter time-frames can become regular. Over all we saw the same trends and anomalies as the 2011 research report with respect to volume change on Mount Rainier.

-12,000,000.00 8,000,000.00 28,000,000.00 48,000,000.00 68,000,000.00 88,000,000.00Lower Carbon

Upper NisquallyUpper PuyallupLower NisquallyLower Tahoma

Lower North MowichUpper WinthropUpper Emmons

Lower WinthropUpper Russell

Lower Ingraham-CowlitzUpper Tahoma

Lower South Ingraham-CowlitzLower South Mowich

Lower PuyallupUpper South Ingraham-Cowlitz

Upper South TahomaUpper Kautz

ParadiseInter

Upper Ingraham-CowlitzLower Kautz

Upper OhanapecoshVan Trump

EdmundsUpper CarbonLower Stevens

WhitmanLiberty Gap

Lower South TahomaLower Russell

SuccessWilliwakas

Lower OhanapecoshEast Flett

Muir SnowfieldLower West Flett

SummitUpper Stevens

Upper West FlettPyramid

Lowe EmmonsUpper North MowichUpper South Mowich

FryingpanVolume Loss 1970 - 2011

Cubic Meters

Project Sisson(2)

Volume* Elevation Volume* Elevation % Volume Diff. % Elevation Diff.Carbon Glacier 87.517 -10.7 97.9 -11.1 -10.61 -3.32Edmunds Glacier 4.0874 -3.2 12.1 -8.8 -66.22 -63.75Emmons Glacier 17.615 -2.3 -13.8 1.2 -227.64 -288.08Fryingpan Glacier -11.621 3.7 -17.2 4.7 -32.44 -22.34Nisqually-Wilson Glacier 74.515 -17.2 93.5 -20.3 -20.30 -15.38Russell Glacier 19.308 -6.4 18.7 -5.7 3.25 12.18South Tahoma Glacier 11.397 -4.3 23.2 -8.1 -50.88 -47.28Tahoma Glacier 48.087 -5.0 83.3 -10 -42.27 -50.20Williwakas Glacier 1.472 -14.3 2 -9.4 -26.40 52.55Winthrop Glacier 39.972 -4.4 24.3 -2.7 64.49 61.96Over all of Shared Names 471.27 564.8 -16.56

*Volumes reported in 106m3

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A S l o w E n d : T r a c k i n g G l a c i e r L o s s o n M o u n t R a i n i e r , W a s h i n g t o n

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Fitted Line PlotHydrology Flow Length = - 235.3 + 0.9981 Bounding Rectangle Length

Pearson correlation coefficient r = 0.95 p-value = 0.000

Thickness LossVariable RecessionPearson Corr. -0.067 n/aSig. 0.661Pearson Corr. -0.061 n/aSig. (2-tailed) 0.691Pearson Corr. -0.04 0.363Sig. (2-tailed) 0.793 0.0004Pearson Corr. -0.186 n/aSig. (2-tailed) 0.22Pearson Corr. -0.506 n/aSig. (2-tailed) 0Pearson Corr. n/a 0.621Sig. (2-tailed) 0.000Pearson Corr. n/a 0.147Sig. (2-tailed) 0.0453Pearson Corr. n/a 0.141Sig. (2-tailed) 0.0549

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When will Mt. Rainier's Glaciers Disappear?

Jonathan Sk loven- Gi l l and M ar i lyn DaumPor t land State Univers i t y GEOG 592 Spr ing 2014

Why Mt. Rainier’sGlaciers Matter

Millimeters90 - 109

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Change in PrecipitationDegrees Celsius

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Change in TemperatureHours / Year

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Glacial Volume Loss C o r r e l a t e d T e m p o r a l V a r i a b l e s

Name Length (Meters) AspectCarbon Glacier 8450.716 NorthEast Flett Glacier 830.539 NorthEdmunds Glacier 2506.334 WestEmmons Glacier 7204.868 NorthEastFryingpan Glacier 3319.733 NorthEastIngraham-Cowlitz Glacier 7133.678 EastInter Glacier 1723.257 NorthEastKautz Glacier 4401.837 SouthLiberty Gap Glacier 2597.644 NorthMuir Snow�eld 1850.982 SouthNisqually-Wilson Glacier 6350.873 SouthNorth Mowich Glacier 4698.779 NorthWestOhanapecosh Glacier 2482.419 EastParadise Glacier 2083.261 SouthEastPuyallup Glacier 4240.209 WestPyramid Glaciers 2123.019 SouthRussell Glacier 3301.068 NorthEastSouth Ingraham-Cowlitz Glacier 5414.88 EastSouth Mowich Glacier 5860.147 WestSouth Tahoma Glacier 5848.794 SouthWestStevens Glacier 1170.132 WestSuccess Glacier 1819.806 SouthSummit Glacier 663.349 EastTahoma Glacier 7755.577 WestVan Trump Glacier 1825.598 SouthWest Flett Glacier 920.09 NorthWhitman Glacier 3032.225 SouthEastWilliwakas Glacier 611.451 SouthEastWinthrop Glacier 8195.913 NorthEast

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How to Calculate Glacier Length?Hydrology Flow Length Minimum Bounding Rectangle Length

longer and closer match to other sourcesgenerally shorter

Projection: NAD 1927 UTM Zone 10

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Predicted Change in Mt. Rainier's Glaciers over TimeApplying NCAR's moderate A1B climate change scenario

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Glaciers as of 2006

Projection: NAD 1927 UTM Zone 10

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