Reconstruction of forest fires through chemical analysis of black carbon in ice cores from high- alpine glaciers Inauguraldissertation der Philosophisch-naturwissenschaftlichen Fakultät der Universität Bern vorgelegt von Dimitri Osmont aus Frankreich Leiterin der Arbeit: Prof. Dr. Margit Schwikowski Departement für Chemie und Biochemie der Universität Bern Reconstruction of forest fires through chemical analysis of black carbon in ice cores from high- alpine glaciers Inauguraldissertation der Philosophisch-naturwissenschaftlichen Fakultät der Universität Bern vorgelegt von Dimitri Osmont aus Frankreich Leiterin der Arbeit: Prof. Dr. Margit Schwikowski Departement für Chemie und Biochemie der Universität Bern Von der Philosophisch-naturwissenschaftlichen Fakultät angenommen. Bern, Der Dekan: Prof. Dr. Z. Balogh Contents List of abbreviations ............................................................................................................................. 7 Summary ................................................................................................................................................ 9 1 Introduction ...................................................................................................................................... 12 1.1 Ice cores as climate archives ....................................................................................................... 12 1.1.1 Current climate change ........................................................................................................ 12 1.1.2 Paleoclimate archives ........................................................................................................... 13 1.1.3 The ice core perspective ....................................................................................................... 15 1.2 Fires, climate and humans ........................................................................................................... 17 1.2.1 Fires: the current situation .................................................................................................... 17 1.2.2 A complex relationship ........................................................................................................ 19 1.2.3 Motivation: the “Broken Fire Hockey Stick” hypothesis..................................................... 20 1.3 Biomass burning proxies in ice cores ......................................................................................... 22 1.3.1 Black carbon ........................................................................................................................ 22 1.3.2 Other proxies ........................................................................................................................ 25 1.3.3 State of the art in ice-core based fire reconstructions .......................................................... 26 1.4 Aim of the study: the PaleoFire project ..................................................................................... 28 References ......................................................................................................................................... 30 2 Ice cores investigated in this thesis ................................................................................................. 39 2.1 Lomonosovfonna, Svalbard ........................................................................................................ 39 2.1.1 Regional settings .................................................................................................................. 39 2.1.2 Ice-core drilling .................................................................................................................... 40 2.1.3 Ice-core dating ..................................................................................................................... 41 2.1.4 Previous studies ................................................................................................................... 42 2.2 Illimani, Bolivian Andes ............................................................................................................. 42 2.2.1 Regional settings .................................................................................................................. 42 2.2.2 Ice-core drilling .................................................................................................................... 44 2.2.3 Ice-core dating ..................................................................................................................... 44 2.2.4 Previous studies ................................................................................................................... 45 2.3 Colle Gnifetti, Swiss Alps ........................................................................................................... 46 2.3.1 Regional settings .................................................................................................................. 46 2.3.2 Ice-core drilling .................................................................................................................... 47 2.3.3 Ice-core dating ..................................................................................................................... 48 2.3.4 Previous studies ................................................................................................................... 49 2.4 Tsambagarav, Mongolian Altai................................................................................................... 49 2.4.1 Regional settings .................................................................................................................. 49 2.4.2 Ice-core drilling .................................................................................................................... 51 2.4.3 Ice-core dating ..................................................................................................................... 51 2.4.4 Previous studies ................................................................................................................... 52 2.5 Summary ..................................................................................................................................... 53 References ......................................................................................................................................... 54 3 Methods ............................................................................................................................................. 59 3.1 Ice-core processing ..................................................................................................................... 59 3.1.1 General procedure ................................................................................................................ 59 3.1.2 Within the PaleoFire project ............................................................................................... 59 3.2 Black carbon analysis ................................................................................................................. 61 3.2.1 The Single Particle Soot Photometer (SP2) ......................................................................... 61 3.2.2 Setup for ice-core analysis ................................................................................................... 63 3.2.3 Routine measurements ......................................................................................................... 64 3.2.4 Optimization with autosampler ............................................................................................ 65 3.3 Major ion analysis ....................................................................................................................... 66 3.4 Water stable isotope analysis ...................................................................................................... 67 3.5 Summary of the analytical work ................................................................................................. 69 References ......................................................................................................................................... 70 4 An 800-year high-resolution black carbon ice core record from Lomonosovfonna, Svalbard . 72 Abstract ............................................................................................................................................. 72 4.1 Introduction ................................................................................................................................. 72 4.2 Methods....................................................................................................................................... 75 4.2.1 Drilling site and ice core characteristics .............................................................................. 75 4.2.2 Sampling, chemical analyses and dating .............................................................................. 75 4.2.3 rBC analysis ......................................................................................................................... 76 4.2.4 BC emission inventories ...................................................................................................... 77 4.2.5 Paleofire detection................................................................................................................ 77 4.3 Results and discussion 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