Title Establishing lichenometric ages for nineteenth- and twentieth-century glacier fluctuations on South Georgia (South Atlantic)
Author Roberts, S.J.; Hodgson, D.A.; Shelley, S.; Royles, J.; Griffiths, H.J.; Deen, T.J.; Thorne, M.A.S.
Author Affil Roberts, S.J., British Antarctic Survey, Cambridge, United Kingdom. Other: University of Cambridge, United Kingdom
Source Lichenometry in subpolar environments, edited by T. Bradwell. Geografiska Annaler. Series A: Physical Geography, 92(1), p.125- 139, . Publisher: Wiley-Blackwell published on behalf of Svenska Saellskapet foer Antropologi och Geografi, Stockholm, Sweden. ISSN: 0435-3676
Publication Date Mar. 2010
Notes In English. 57 refs. Ant. Acc. No: 91613. GeoRef Acc. No: 310335
Index Terms climatic change; geochronology; glaciers; Scotia Sea; Atlantic Ocean--South Atlantic; Atlantic Ocean Islands--South Georgia; Atlantic Ocean; Atlantic Ocean Islands; case studies; Cenozoic; climate change; climate effects; deglaciation; frequency; glacial features; growth rates; Holocene; lichenometry; moraines; Quaternary; relative age; Scotia Sea Islands; size; South Atlantic; South Georgia; upper Holocene
Abstract Glaciers in small mountain cirques on South Georgia respond rapidly and sensitively to changes in South Atlantic climate. The timing and rate of their deglaciation can be used to examine the impact that nineteenth- and twentieth-century climate change has had on the glacial dynamics and terrestrial ecosystems of South Georgia. As part of a reconnaissance study in Prince Olav Harbour (POH), South Georgia, we measured the size of lichens (Rhizocarpon Ram. em Th. Fr. subgenus. Rhizocarpon group) on ice-free moraine ridges around two small mountain cirques. Our aims were twofold: first, to provide age estimates for lichen colonization, and hence, deglaciation of the moraine ridges, and second, to examine the potential of applying lichenometry more widely to provide deglacial age constraints on South Georgia. In the absence of lichen age-size (dating) curves for South Georgia, we use long-term Rhizocarpon lichen growth- rates from recent studies on sub-Antarctic Islands and the western Antarctic Peninsula to calculate likely age estimates. These data suggest ice retreat from the two outermost moraines occurred between the end of the 'Little Ice Age' (post c. 1870) and the early twentieth century on South Georgia. Lichen colonization of the innermost moraines is probably related to glacier retreat during the second half of the twentieth century, which has been linked to a well-defined warming trend since c. 1950. Patterns of possible nineteenth- and twentieth-century glacial retreat identified in POH need to be tested further by establishing species- and site-specific lichen age-size (dating) curves for South Georgia, and by applying lichenometry to other mountain cirques across South Georgia. Abstract Copyright (2010), Swedish Society for Anthropology and Geography.
URL http://hdl.handle.net/10.1111/j.1468-0459.2010.00382.x
Publication Type journal article
Record ID 65007235