Holocene lake-climate interactions in West Greenland: a synthesis
by
N. John Anderson
Department of Geography, University of Copenhagen
Coauthors: K.P. Brodersen (GEUS), A. Clarke (University of Liverpool), M.J. Leng (NERC Isotope Geosciences Laboratory), S. McGowan (University of Regina), D.B. Ryves (GEUS)

The Søndre Strømfjord region (Kangerlussuaq, ca. 67° N, 50-54° W) is the widest, ice-free area in West Greenland and contains thousands of lakes of varying size and type. Despite relatively uniform geology and vegetation (dwarf shrub tundra), water chemistry is quite variable; lake-water conductivity, for example, ranges from ~20 to 4000 uS/cm. The highest values are found in the oligosaline, meromictic lakes at the head of the fjord and reflect the very low levels of effective precipitation close to the ice margin, where the climate is continental. The coastal zone is slightly more maritime with higher precipitation and a reduced mean annual temperature range and more dilute lakes. As this marked climatic gradient is combined with low levels of anthropogenic impact and a relatively simple trophic structure (many lakes are fishless), the area is particularly well-suited for studying lake-catchment-climate interactions, at a variety of spatial and temporal scales.

There is considerable physical evidence for changes in climate, especially effective precipitation, most notably the numerous fossil shorelines. The development of meromixis is coincident with evidence for lake-level lowering and is confined to those lakes closer to the head of the fjord. The meromictic lakes have distinctly laminated sediments, but laminations are also found in more dilute, dimictic lakes. There is probably a complex relationship between lake area-catchment ratios, lake depth, location and regional climate. Our limnological and palaeolimnological studies in this area, therefore, have focussed on:

1. determining contemporary lake responses to the dominant climate gradients in the area: maritime-continental (coast to ice sheet) and altitudinal, 2. assessment of community response to climatic variability during the Holocene. We have used a multiproxy approach (diatoms, chironomids, isotopes and magnetics) in our attempts to identify lake community response to climatic change in this area. The results to date suggest that the lakes around Søndre Strømfjord offer a clear regional-scale record of Holocene climatic change for this area, that complements that from the Greenland ice cores. in particular, the early Holocene was a period of rapid climate adjustment in this area, and considerably drier than it is today.

Date received: May 15, 2001

Copyright © 2001 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cahr-06.