Scaling-up Climate Change Effects in Greenland Stine Højlund Pedersen PhD Thesis 2017 1 Scaling-up Climate Change Effects in Greenland Stine Højlund Pedersen PhD Thesis 2017 Graduate School of Science and Technology, Aarhus University, Denmark. Department of Bioscience, Greenland Ecosystem Monitoring, Arctic Research Centre 2 Data sheet Title: Scaling-up Climate Change Effects in Greenland Subtitle: PhD Thesis Author: Stine Højlund Pedersen Institute: Department of Bioscience, Arctic Research Centre, Aarhus University, Denmark and Greenland Ecosystem Monitoring. Publisher: Aarhus University, Denmark URL: www.bios.au.dk/en/ Year of publication: 2017 PhD supervisors: Senior Researcher Niels Martin Schmidt and Senior Researcher Mikkel P. Tamstorf, Aarhus University, Denmark, and Dr. Glen E. Liston, Cooperative Institute for Research in the Atmosphere, Colorado State University, U.S.A. Assessment Associate Professor Dr. Marc Macias-Fauria, School of Geography and the committee: Environment, University of Oxford, UK., Professor Dr. Jason E. Box, Department of Glaciology and Climate, The Geologic Survey of Denmark and Greenland (GEUS), Denmark, and Senior Researcher Dr. Morten Frederiksen, Department of Bioscience, University of Aarhus, Denmark. Please cite as: Højlund Pedersen, S. 2017. Scaling-up Climate Change Effects in Greenland. PhD Thesis. Aarhus University. Department of Bioscience, Denmark. 178 pp Abstract: In ice-free Greenland, extensive knowledge and a mechanistic understanding of interactions between abiotic and biotic ecosystem components have been gained from observations collected in the Greenland Ecosystem Monitoring (GEM) sites during 10-20 years. This PhD project was initiated to facilitate an understanding of these interactions also in between observational sites using up-scaling. Since, the seasonal snow cover is a key driver of changes in Arctic ecosystems, snow is the main focus of this interdisciplinary study. The project aim was twofold; (i) to quantify the spatial and temporal changes and variability in snow characteristics across multiple spatial scales and time periods in ice-free Greenland, and (ii) to investigate the effects of these snow changes and variability on biotic components of the ecosystems. This was accomplished by combining ground-based observations, spatial-temporal snow and atmospheric modeling tools, and remotely sensed vegetation greenness in a stepwise up-scaling to gradually larger domain extents. Keywords: Snow, vegetation greenness, gradients, observations, modeling, scales, remote sensing, Greenland. Layout and all photos: Stine Højlund Pedersen Front cover: Freshly fallen snow in the morning near Tasiilaq, East Greenland. Back cover: Heavily eroded snow surface at sunset near Qassiarsuk, West Greenland. ISBN: 978-87-93129-39-9 Printed by: LaserTryk.dk A/S Circulation: 50 Time and place of 24 February 2017 at 13:00, Niels Bohr Auditorium, Aarhus University, Department defence: of Bioscience, Frederiksborgvej 399, 4000 Roskilde, Denmark Animations: 3 Table of Contents Data sheet ...................................................................................................................................................... 2 Preface ........................................................................................................................................................... 5 Acknowledgements ....................................................................................................................................... 6 List of included papers .................................................................................................................................. 8 List of additional contributions...................................................................................................................... 9 Summary ......................................................................................................................................................10 Resumé (Summary in Danish) ......................................................................................................................12 Eqikkaaneq (Summary in Greenlandic) .......................................................................................................14 Seasonal snow cover in the Arctic ecosystems.............................................................................................16 Snow monitoring in Greenland.....................................................................................................................17 Challenges in research of changing Arctic snow cover: a scale/resolution mismatch between observations, modeling, and impacts. .................................................................................................................................17 Scaling-up from point to region to entire ice-free Greenland .......................................................................18 Scale-dependent modeling representing processes at relevant resolution ....................................................18 Inclusion of ground observations .............................................................................................................20 Stepwise knowledge-gain in time and space across multiple scales ............................................................21 Local scale ................................................................................................................................................21 Regional scale ...........................................................................................................................................22 Entire ice-free Greenland .........................................................................................................................22 Looking into the future .................................................................................................................................23 Perspectives and Concluding remarks ..........................................................................................................23 References ....................................................................................................................................................25 Paper I .............................................................................................................................................................. Paper II ............................................................................................................................................................ Paper III ........................................................................................................................................................... Paper IV ........................................................................................................................................................... Paper V ............................................................................................................................................................ Paper VI ........................................................................................................................................................... Paper SI ........................................................................................................................................................... Paper SII .......................................................................................................................................................... Paper SIII ......................................................................................................................................................... Paper SIV ........................................................................................................................................................ 4 5 Preface This thesis represents a partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) at the Faculty of Science and Technology, Aarhus University, Denmark. The research presented in this thesis is the results of a four year PhD project conducted at Department of Bioscience and Arctic Research Centre, Aarhus University under the supervision of Niels Martin Schmidt, Mikkel P. Tamstorf, and Glen E. Liston. A part of the results are produced in collaboration with international as well as Danish colleagues, all of whom are listed as co-authors of the respective papers. The thesis includes an introduction describing the aims, data sources, challenges, and methodology of the PhD project. Hereafter, I summarize and synthesize the findings of the four published papers, a manuscript, and an extended abstract (Paper I-VI) comprising the thesis. When I started my university education almost ten years ago, my wish was to understand and figure out how the nature around me was functioning. One of the requests to the part of nature, I was going to study, was that it had to vary over relatively short time spans, for example between seasons or from year to year, unlike processes evolving over millions of years. Therefore, I pursued the field of physical geography and learned about passing weather systems, river discharge, plant and soil gas-flux exchange, and temperature fluctuations. But I fell in love with the science of snow and not least in Greenland. And I promise you that very early in my PhD studies my desire for the volatile nature of snow was met. An early morning in March