GLACIER FLUCTUATIONS AND CLIMATIC CHANGE IN SOUTHEAST ICELAND OVER THE LAST 1000 YEARS

This poster examines the spatial and temporal expression of glacier fluctuations in southeast Iceland over the last millennia The study uses geomorphological evidence to reconstruct the former extent of Lambatungnajokull - a non-surging, valley glacier flowing from the eastern flank of the Vatnajokull ice-cap. Lichenometry is used to date recent glacial landforms and decode the pattern of glacier fluctuations over the last 300 years. Tephrochronology is used to date the minimum age of older features. The results of this research show a pattern of glacier fluctuations driven by climatic change. Between AD 1000-1600, Lambatungnajokull was less extensive than during more recent centuries. Moraines dated using two different lichenometric techniques indicate that the most extensive period of glacier expansion during 'historical' time culminated shortly before c. AD 1795, probably in the 1780s. Recession over the last 200 years has been interrupted by re-advances in the 1850s, 1870s, and c. 1890. In the 20th century, most notably in the 1930s and 1940s, Lambatungnajokull receded more rapidly than at any time during the previous 150 years. The degree and nature of glacier retreat since 1930 compares well with similar-sized valley glaciers in southern Iceland (eg. Solheima-, Skaftafells-, and Skalafellsjokull). Much of the climatic variation experienced in southern Iceland, and the glacier fluctuations that result, can be explained by secular changes in the North Atlantic Oscillation. A shift to more zonal atmospheric circulation and a weaker Icelandic Low may have been responsible for the cooling and associated glacier advances of the 18th and 19th centuries. One implication of this work relates to the exact timing of the Little Ice Age in the Northeast Atlantic. The very advanced position of glaciers during the 18th century suggests that this period represented the culmination of the Little Ice Age in Iceland. This contrasts with the current consensus of a Little Ice Age glacier maximum in southern Iceland during the late 19th century.