| Summary: | A key issue in studies of Norse settlement in Iceland is the role that climate has played in shaping the history of the island. The thesis has two main objectives: (1) to constrain the timing and nature of any significant variations in climate during the Medieval period, and around the time of Norse settlement in Iceland (c.500-1500AD). (2) to evaluate likely impacts post-settlement of such changes upon those living in Iceland. To do this, the project uses a multidisciplinary approach, combining new empirical data, existing empirical and documentary data, and a new climate model for Iceland. Medieval glacier retreat was examined using lacustrine sediment sequences collected from two localities, that from SkeiSsvatn in Trollaskagi being notable as of being at least 1350 years in length. At Skeibsvatn, lacustrine evidence indicates the onset of Late Holocene glaciation around A.D. 650, and that glaciation of the catchment has continued uninterrupted to the present day. This constrains the warmth of the 'Medieval Warm Period', while terminal moraines constrain both 'Little Ice Age' and earlier Neoglacial advances. This is the first such lacustrine record of glacier retreat from Iceland. Two models are presented in the thesis, the most important being an original massbalance and vegetation cover model. The first modelling approach used is to apply the threedimensional ice sheet model GLIMMER to test the sensitivity of selected small glaciers to growth and disappearance. The second modelling approach was the construction of a new model of climate and vegetation for Iceland. The Iceland climate model is Java-based, and includes well over 12,000 lines of original code. It shows that it is possible to model monthly and annual vegetation limits, snowlines and snowcover based on inputs of primarily topography, temperature and precipitation, and constrain the modelling using glacier mass balance. This model has been used to evaluate spatial and temporal environmental responses to changes in temperature and ...
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