Department of Physical Geography Mapping glacier change in Sweden between the end of ‘Little Ice Age’ and 2008 with orthophotos and a Digital Elevation Model Moa Hamré Master’s thesis NKA 132 Physical Geography and Quaternary Geology, 60 Credits 2015 Preface This Master’s thesis is Moa Hamré’s degree project in Physical Geography and Quaternary Geology at the Department of Physical Geography, Stockholm University. The Master’s thesis comprises 60 credits (two terms of full-time studies). Supervisors have been Peter Jansson, Gunhild Rosqvist and Per Holmlund at the Department of Physical Geography, Stockholm University. Examiner has been Margareta Hansson at the Department of Physical Geography, Stockholm University. The author is responsible for the contents of this thesis. Stockholm, 8 October 2015 Steffen Holzkämper Director of studies Moa Hamré Cover Photo: Matthias Rieckh 1 Mapping glacier change in Sweden between the end of ‘Little Ice Age’ and 2008 with orthophotos and a Digital Elevation Model Abstract Swedish glacier extent change since the glacial end of the ‘Little Ice Age’ (LIA; ~1916) to 2008 was assessed with orthophotos from 2008, a Digital Elevation Model (DEM), topographic and geomorphological maps, historical photos together with previous inventories from 1950s/1960s, 2002 and 2008. Glacier area for 294 glaciers for LIA and 2008 were manually digitized where the LIA extents were determined mainly from moraines visible in orthophotos. A Geographical Information System-based method (GIS) was applied for calculating the glacier area, volume, slope, aspect, elevation and hypsometry, and the change of the parameters was then calculated. The total glacierized area decreased with 127 ± 7 km2 from the end of LIA to 2008 corresponding to 34 ± 7% or an estimated volume loss of 7.9 km3 (41%). Glaciers with an area smaller than 1.0 km2 represent 78% of all the glaciers in 2008. These glaciers have suffered the largest relative area change contributing to as much as 32% of the total area loss. An increasing scatter of glacier area change and topographic character with decreasing glacier size was also found. These results illustrates the importance of including a large sample of studied glaciers covering all size classes to understand the glaciers response to climate change of a region. The relative area decrease since the end of LIA for Swedish glaciers of 34% is the same as that detected for Jotunheimen, southern Norway between 1750 and 2003 (35%), smaller compared to the change recorded in the European Alps (50% between 1850 and 2000) and in the Southern Alps of New Zealand (49% between 1850 and 1975) and larger compared to glaciers located on Baffin Island, Canada (13% between 1920 and 2000). Between 2002 and 2008 the rate of area decrease has increased to 1.6% yr-1 compared to 0.3% yr-1 for the period between 1916 and 2002. Thus, if this rate of glacier recession continues most glacier area could be lost by 2070. 2 Moa Hamré 3 Mapping glacier change in Sweden between the end of ‘Little Ice Age’ and 2008 with orthophotos and a Digital Elevation Model Table of centens Abstract ............................................................................................................................. 2 1. Introduction ................................................................................................................... 6 1.1. Aim of study ........................................................................................................... 7 2. Background ................................................................................................................... 8 2.1. Glaciers response to climate change ...................................................................... 8 2.2. Holocene climate and glacier extent during and after the LIA ............................ 10 2.2.1. Swedish climate and glacier extent during the LIA ...................................... 10 2.2.2. Swedish climate and glacial retreat since the end of LIA ............................. 13 2.3. Remote sensing as method for regional glacier area and volume change calculation ................................................................................................................... 14 2.3.1. Uncertainty estimation in previous studies ................................................... 15 2.4. Volume-area scaling ............................................................................................. 16 3. Study area .................................................................................................................... 17 4. Data ............................................................................................................................. 19 4.1. Orthophotos and Digital Elevation Model ........................................................... 19 4.2. Previous inventories ............................................................................................. 20 4.3. Topographic and geomorphological map and photos .......................................... 21 5. Methods ....................................................................................................................... 22 5.1. Identifying glaciers for 2008 and LIA .................................................................. 22 5.2. Defining the 2008 glacier area extent .................................................................. 25 5.3. Defining the end of LIA glacier area extent ......................................................... 27 5.4. Creating inventory data ........................................................................................ 28 5.4.1. Glacier ID and name ..................................................................................... 28 5.4.2. Area change calculation and comparison with previous inventories ............ 29 5.4.3. Volume-area scaling ...................................................................................... 29 5.4.4. Topographic parameters ................................................................................ 29 5.5. Uncertainty analysis ............................................................................................. 30 6. Results ......................................................................................................................... 33 6.1. Uncertainty analysis ............................................................................................. 33 6.2. Glacier number and size distribution ................................................................... 36 6.3. Area change .......................................................................................................... 37 6.4. Volume change ..................................................................................................... 42 6.5. Temporal area change in Sweden and other regions of the world ....................... 43 6.6. Topographic parameters ....................................................................................... 44 4 Moa Hamré 6.6.1. Slope ............................................................................................................. 44 6.6.2. Aspect ........................................................................................................... 45 6.6.3. Elevation ....................................................................................................... 48 7. Discussion ................................................................................................................... 50 7.1. Uncertainty analysis ............................................................................................. 50 7.2. Area and volume change in relation to size and topographic parameters of the glaciers ........................................................................................................................ 52 7.2.1. Scatter of smaller glaciers character ............................................................. 54 7.2.2. The effect of aspect on area and volume change .......................................... 56 7.3. Temporal area and volume change compared to other regions ........................... 57 7.3.1. Area and volume change in Sweden between the end of LIA until the twenty-first century compared to other glacier regions .......................................... 57 7.3.2. Accelerating area and volume change since 1990s ...................................... 59 8. Conclusions ................................................................................................................. 62 9. Recommendations for further work ............................................................................ 63 Acknowledgments .......................................................................................................... 64 References ....................................................................................................................... 65 Appendix A ..................................................................................................................... 75 A.1. Individual glacier data ......................................................................................... 75 A.2. Maps of glacier location and glacier ID for 2008 ............................................... 82 Appendix B. Regression analysis ................................................................................... 88 Appendix C. Complementary results of glacier parameters ..........................................