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Title: The 'Little Ice Age' maximum in South East Iceland : integrating the glacial, climatic and historical records of change
Author: McKinzey, K. M.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2005
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Abstract:
This thesis investigates the ‘Little Ice Age’ (LIA) glacial maximum in southeast Iceland through integration of the glaciological, climatological and historical records of change in order to enhance current understanding about the timing, expression and consequences of glacier-climate interactions in the North Atlantic. Iceland’s proximity to large scale climatic drivers, such as the thermohaline circulation and North Atlantic Oscillation (NAO), indicates that its glaciers may provide one of the clearest signals of oceanic-atmospheric interactions at a range of time-scales. Previous opinions have differed regarding the timing of the LIA maximum extensive of Icelandic glaciers with possibilities generally ranging from the mid-/late- 18th to late 19th centuries. Moraines along the margins of Skálafellsjökull and Heinabergsjökull, two Vatnajökull outlet glaciers in southeast Iceland, were re-dated in order to examine whether disparities may have arisen due to differing glacier response rates, selective preservation of evidence or unreliable dating techniques. Approximately 12,000 lichens were measured on 40 moraine fragments to provide surface age proxies. The population gradient lichenometric technique yields late 18th to early 19th century moraine dates, whereas the conventional ‘average of the five largest’ method clusters moraine dates to the late 19th century. Subsequently, an updated tephrochonology for southeast Iceland (geochemistry and tephrastratigraphy) based on 25 reference soil profiles was used to identify tephra layers within 15 additional soil profiles dug around the LIA moraines. Tephrochonology confirms that the LIA maximum extent for both glaciers occurred between AD 1755 and 1873. A late 18th to early 19th century LIA maximum at Skálafellsjökull and Heinabergsjökull accords with widespread glacial maxima (extent and ice volume) across Iceland, indicative of a pervasive response to climatic deterioration. A positive degree-day mass balance model was implemented for Skálafellsjökull, Heinabergsjökull and Lambatungnajökull to assess the linkages between spatial expression of LIA glacier maxima with potential climatic envelopes during the late 18th to early 19th centuries. Reconstructions suggest that glacier mass balance was at least 1.5 to 2 mwe a-1 greater than at present induced by a ~1-1.5°C temperature reduction associated with severe sea-ice years during the 1780s. Equilibrium line altitudes may have lowered by ~140 m during the LIA maximum. The model also indicates that glacier hypsometry significantly affects differential response of the three Vatnajökull outlet glaciers under various climatic regimes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.666319  DOI: Not available
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