Recent environmental change and atmospheric contamination on Svalbard as recorded in lake sediments – an introduction*

This paper outlines an interdisciplinary project on recent environmental change and atmospheric contamination on the high Arctic archipelago of Svalbard (76o30'N – 80o30'N). It describes the rationale and aims of the project and summarises the location, climate, geology, vegetation, and land-use of Svalbard. Introduction The Arctic constitutes a unique and important environment with a significant role in the dynamics and evolution of the earth system. High Arctic biota and environments have long been assumed to be relatively ‘pristine’ and ‘stable’ because of the absence of any intensive local human impact and of any significant atmospheric contamination. Arctic biotic assemblages are commonly thought to have changed little over the last few thousand years. However, Overpeck et al. (1997) have shown, using a range of proxy data sources (e.g., ice cores, tree rings) that the Arctic has undergone significant climatic changes during the recent past, with a marked warming since the mid-19 century. These changes appear to be unprecedented when put in the context of available climatic time-series for the last 400 years (Overpeck op. cit.). Additionally, environmental changes such as declines in the total area of winter-snow cover on land and of declining sea-ice cover throughout the Arctic Ocean, are now well documented. These progressive changes are occurring across the very region where General Circulation Models predict the earliest and largest greenhouse warming (IPCC 2001). Although inter-annual to century-scale climatic variation may be the norm in the Arctic (Overpeck op. cit.), there are very few historical biological, chemical, or palaeoecological data from the high Arctic, especially in Europe, to test for biotic responses to recent environmental change. The lack of such data is particularly critical as the Arctic is increasingly being recognised as an area that is potentially highly susceptible to global warming as well as being very sensitive to impacts from atmospheric pollutants. Lake-sediment records from high Arctic lakes can provide unique data on recent biotic changes and pollution levels in remote areas where expensive long-term monitoring has not been possible. By analysing the fossil and chemical composition of lake sediments and by deriving an independent chronology for the sediments by means of Pb-dating, it is possible to consider questions such as what is the rate and direction of recent change in lake biota and what is the timing and magnitude of atmospheric contamination? Additionally, the stability of Arctic biotic assemblages and their response to recent environmental change, and the extent of recent changes in lake trophic status and acidity, all of which can be influenced directly or indirectly by changes in climate and pollution, can be examined. High Arctic lakes may be among the most sensitive ecosystems to climatic change and to atmospheric pollution because although there may be high mid-summer productivity in some lakes, the brief growing-season ensures a low annual production compared to lakes further south. Chemical weathering rates influence, in part at least, the supply of nutrients to lakes and these rates can themselves be strongly influenced by climate (Smol et al. 1991). With funding from the Norges forskningsråd (Norwegian Research Council), we began in 1995 a multi-disciplinary project on ‘Lake sedimentary records of recent atmospheric pollution and environmental change on Spitsbergen’. This issue of Journal of Paleolimnology brings together the results of the various studies carried out as part of this project. These included simple basic surveys of a range of lakes and their catchments in western Svalbard, together with sampling of recent and surface sediments.