The Little Ice Age glacier maximum in Iceland and the North Atlantic Oscillation: evidence from Lambatungnajökull, southeast Iceland

Abstract

This article examines the link between late Holocene fluctuations of Lambatungnajökull, an outlet glacier of the Vatnajökull ice cap in Iceland, and variations in climate. Geomorphological evidence is used to reconstruct the pattern of glacier fluctuations, while lichenometry and tephrostratigraphy are used to date glacial landforms deposited over the past ˜400 years. Moraines dated using two different lichenometric techniques indicate that the most extensive period of glacier expansion occurred shortly before c. AD 1795, probably during the 1780s. Recession over the last 200 years was punctuated by re‐advances in the 1810s, 1850s, 1870s, 1890s and c. 1920, 1930 and 1965. Lambatungnajökull receded more rapidly in the 1930s and 1940s than at any other time during the last 200 years. The rate and style of glacier retreat since 1930 compare well with other similar‐sized, non‐surging, glaciers in southeast Iceland, suggesting that the terminus fluctuations are climatically driven. Furthermore, the pattern of glacier fluctuations over the 20th century broadly reflects the temperature oscillations recorded at nearby meteorological stations. 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 (NAO) Advances of Lambatungnajökull generally occur during prolonged periods of negative NAO index. The main implication of this work relates to the exact timing of the Little Ice Age in the Northeast Atlantic. Mounting evidence now suggests that the period between AD 1750 and 1800, rather than the late 19th century, represented the culmination of the Little Ice Age in Iceland.

Observations: Cryosphere

“…In particular, the findings of Humwell et al (2005) and Bradwell et al (2006) suggest in some Arctic regions twentieth century air temperatures peaked in the 1930s and 1940s, followed by a cooling that persisted through the end of the century. This thermal behavior is about as different as one could imagine from the steady warming claimed by the IPCC to have occurred around the globe through the twentieth century and especially over the last four decades.…”

“…• In a late Holocene study, Bradwell et al (2006) examined the link between fluctuations of Lambatungnajokull glacier, southeast Iceland, and variations in climate. Comparison between the glacial history and instrumental records show over the past four centuries "there is a particularly close correspondence between summer air temperature and the rate of ice-front recession of Lambatungnajokull during periods of overall retreat"; recession was greatest during the 1930s and 1940s, when it averaged 20 m/year, but thereafter it slowed so "there has been little overall retreat since the 1980s."…”

Snæfellsjökull volcano-centred ice cap landsystem, West Iceland

“…Together with the most recent push moraines (see Section 3.2), this moraine belt possibly marks the position of the mid to late 1990s readvance margin, a feature identified at a range of locations around Iceland (e.g. Bennett & Evans, 2012;Bradwell et al, 2006;Evans et al, 2009Evans et al, , 2015bEvans & Hiemstra, 2005).…”

“…Localized exposures through the push ridges reveal deformed stratified sediments indicative of recent glacier readvance into proglacial outwash, potentially driven by the mid to late 1990s positive mass balance trends recognized throughout Iceland (e.g. Bennett & Evans, 2012;Bradwell, Dugmore, & Sugden, 2006;Evans & Hiemstra, 2005;Evans, Shand, & Petrie, 2009, 2015b.…”

Application of the Handysurf E-35B electronic profilometer for the study of weathering micro-relief in glacier forelands in SE Iceland

“…However, there is some uncertainty about the oldest moraine ridges in S Iceland (Kirkbridge and Dugmore 2001;Bradwell 2001Bradwell , 2004McKinzey et al 2004;Bradwell et al 2006;Chenet et al , 2011Dąb-ski 2010), and the oldest moraines could have been created in the 18 th or even 17 th centuries, or could have been eroded (Kirkbridge and Winkler 2012). The recession rate, as well as the age of test sites, is shown on Text- fig.…”