OCR Text |
Show 168 STIKINE ICECAP FLUCTUATION Jewell Lund (Richard R. Forster) Department of Geography University of Utah RESEARCH POSTERS ON THE HILL SPRING 2012 INTRODUCTION Glaciers and icecaps are garnering attention in the flux of climate change because they both present a challenge in modeling climate change, as well as display great sensitivity to climate. While focus has been placed on large volume ice sheets, such as Greenland and Antarctica, mountain icecaps present a contribution to global sea level rise that is less understood and is important. The Stikine Icecap, located in Southeast Alaska, is part of the Gulf of Alaska mountain glacier system that is the largest known contributor to global sea level rise of all mountain glacier systems (Meier et. al, 2007). In order to better understand the changes of the Stikine Icecap in recent decades, satellite images of the icecap were collected at the end of glacial melt season. Images were collected for both the 1979-1980 seasons, as well as the 2011 season. These images were then used in the ArcMap GIS program to create digitized maps of the icecap. These digitized images were created to aid GLIMS (Global Land Ice Measurements from Space), a project designed to monitor the world's glaciers using satellite images. Data comparison of these digitized images provides an objective view on glacial area change in the past thirty years. METHODS Landsat 7 images were chosen for this project based on both image clarity, as well as image date, in order to capture the Stikine Icecap after the greatest seasonal melt had occurred. The glaciers in these images were then digitized using ArcMap software. The final shapefiles of the 1979-1980 image, digitized first, were used as a baseline for the 2011 image. Once the results of both shapefiles were cleaned and matching, the data from both shapefiles was joined. This joining of data allowed a direct comparison of glacial area for both years. STIKINE ICE CAP VARIATION JEWELL LUND & PROFESSOR RICK FORSTER DEPARTMENT OF GEOGRAPHY Student Photo Faculty Photo Logo For Student Support Image lower left 4 Image lower middle 5 TERMINUS RETREAT: 2.833 KM SHAKES GLACIER TERMINUS RETREAT: 3.008 KM WORKS CITED Meier, M.F. et.al, 2007. Glaciers dominate eustatic sealevel rise in the 21st century. Science, 317(5841), 1064-1067 DAWES GLACIER TERMINUS RETREAT: 2.972 KM STIKINE ICE CAP 1980 TO 2011 IMAGE SOURCE: HTTP://REVERB.ECHO.NASA.GOV CARTOGRAPHER: JEWELL LUND RESULTS The digitization of the Stikine Icecap created a vast amount of data, with glaciers/icefields ranging in area from 0.149 to 730.894 square kilometers. Visual comparison of the images implies an overall area loss to the Stikine Icecap from 1980 to 2011, mostly noticeable in the retreating termini of the glaciers, especially tidewater or lake-water terminating glaciers. Statistics support visual assessment. CONCLUSION Statistics and images both indicate that larger glaciers within the Stikine Icecap-particularly those glaciers terminating in either tidewater or lakes-have significantly decreased in area from 1979-1980. Further exploration into the transformation of these water terminating glaciers will provide insight into current dynamics of the Stikine Icecap. JEWELL LUND RICK FORSTER STIKINE 2011 BIGGEST LOSERS GLACIER NAME 2011 AREA (KM2) 1980 AREA (KM2) AREA CHANGE (KM2) PERCENT AREA CHANGE TERMINATI ON TERMINUS RETREAT (KM) DAWES 556.497 612.028 -55.531 -9.07 Tide -2.972 BAIRD 699.315 730.894 -31.579 -4.32 Tide 0.00 SOUTH SAWYER 630.659 659.153 -28.494 -4.32 Tide -1.457 SAWYER 128.630 144.777 -16.147 -11.15 Tide -2.833 TRIUMPH 65.729 75.950 -10.221 -13.46 Lake -1.320 SAWYER INTO WHITING LAKE 220.575 230.299 -9.724 -4.22 Land -1.217 GREAT 155.263 164.410 -9.147 -5.56 Lake -2.676 LE CONTE 457.899 465.457 -7.558 -1.62 Lake -1.173 FLOOD 117.213 124.540 -7.327 -5.88 Lake -1.262 WRIGHT 137.448 144.702 -7.254 -5.01 Tide -0.825 FACTS AT A GLANCE GLACIERS/ICEFIELDS 587 GLACIERS/ICEFIELDS LOSING AREA 472 1980 TOTAL AREA (KM2) 6101.202 2011 TOTAL AREA (KM2) 5656.959 TOTAL AREA CHANGE (KM2) -444.244 PERCENT TOTAL AREA CHANGE -7.281 Introduction Glaciers and icecaps are garnering attention in the ux of climate change because they both present a challenge in modeling climate change, as well as display great sensitivity to climate. While focus has been placed on large volume ice sheets, such as Greenland and Antarctica, mountain icecaps present a contribution to global sea level rise that is less understood and is important. The Stikine Icecap, located in South east Alaska, is part of the Gulf of Alaska mountain glacier system that is the largest known contribu tor to global sea level rise of all mountain glacier systems (Meier et. al, 2007). To better understand the changes of the Stikine Icecap in recent decades, satellite images of the icecap were collected at the end of glacial melt season. Images were collected for both the 1979-1980 seasons, as well as the 2011 season. These images were then used in the ArcMap GIS program to create digitized maps of the icecap. These digitized images were created to aid GLIMS (Global Land Ice Measurements from Space), a project designed to monitor the world's glaciers using satel-lite images. Data comparison of these digitized images provides an objective view on glacial area change in the past thirty years. Results Visual comparison of the images implies an overall area loss to the Stikine Icecap from 1980 to 2011, mostly noticeable in the retreating termini of the glaciers, especially tidewater or lake-water terminat-ing glaciers. Statistics support visual assessment. Of 587 digitized glaciers and ice elds, 472 lost area. The area change from 1980 to 2011 is -444.244 square kilometers, an overall loss of 7.281%. The furthest terminus retreat measured 3.178 kilometers. Further exploration into the transformation of these water terminating glaciers will provide insight into current dynamics of the Stikine Icecap. Meier, M.F. et.al, 2007. Glaciers dominate eustatic sealevel rise in the 21st century. Science, 317(5841), 1064-1067 |