Combined Palaeolimnological and Glacial Geomorphological Reconstruction of Environmental Change in Southeast Iceland

Iceland offers an excellent location to investigate North Atlantic Holocene climate change, due to its setting in the North Atlantic Ocean, where atmospheric and ocean patterns have a significant influence on terrestrial climate. Sub-Arctic locations such as Iceland are sensitive to climatic change and palaeoclimatic records are important for understanding Holocene climate variability and the mechanisms behind these changes. This thesis presents a combined palaeolimnological and glacial geomorphological record of Little Ice Age (LIA) environmental and climatic change since AD ~1440. Despite the growing body of research on chironomid-based studies in Iceland, no records yet exist for southeast Iceland. This lake sediment record from Káravatn includes the first chironomid-inferred temperature (C-IT) record for southeast Iceland, that provides quantitative July temperature estimates, by applying both the Icelandic (Langdon et al., 2008) and Arctic (Medeiros et al., 2022) transfer functions. The C-IT reconstructions have been validated using instrumental temperature measurements from nearby meteorological stations. The lake sediment core was dated using AMS radiocarbon dating and tephrochronology, to provide a well-constrained dating model throughout the core. Sedimentological analysis included magnetic susceptibility, loss on ignition, particle size analysis and geochemical (Itrax) data. The C-IT record, chironomid assemblage and sedimentological data show a cold phase occurring between AD ~1770 and ~1850, which agrees with other palaeoclimatic and glaciological studies. New glacial geomorphological mapping using high-resolution Uncrewed Aerial Vehicle (UAV) data is presented for Skálafellsjökull, an outlet glacier of the Vatnajökull ice cap. Ice margin reconstructions from aerial imagery and geomorphology were used to propose a conceptual model of deglaciation since the end of the LIA, initiated by rapid warming in the early 20th century and influenced by underlying bedrock topography. This combined glacial and palaeoclimatic record has expanded our understanding LIA climate in southeast Iceland, which is important for producing accurate glaciological and climatic simulations.