Landscape control of high latitude lakes in a changing climate

Abstract

Lakes are the downstream integrators of their surrounding catchments and are therefore highly responsive to variations in landscape properties. High latitude lakes share many characteristics with those of temperate latitudes and are subject to many of the same landscape controls. However, polar lakes and their catchments also experience persistent low temperatures, extreme seasonality and severe freeze-thaw cycles and these distinguishing features are likely to amplify their responsiveness to landscape and climate change. General circulation models vary in their prediction of the future magnitude of regional climate change, but almost all converge on the conclusion that the polar regions will experience greater temperature increases than elsewhere and that these changes are likely to occur ever faster because of the positive feedback effects of melting snow and ice. Observations in the north polar region have shown that there have been significant rises in temperature throughout much of the area in recent decades, with effects on permafrost, lake ice cover, glacial extent and ice shelf break-up (Serreze et al. 2000, Mueller et al. 2003, ACIA 2004). Recent analysis of long term monitoring data from maritime Antarctic Signy Island (South Orkney Islands) and the McMurdo Dry Valleys in continental Antarctica has provided evidence of large regional variations in climate change and has shown that south polar lakes respond strongly to warming and cooling trends (Doran et al. 2002, Quayle et al. 2002, 2003). In this review, we take a two-step approach towards examining climatelandscape- lake interactions in high latitude environments. First, we examine the general effects of landscapes on lake ecosystems through factors such as geomorphology, solute transport, vegetation and hydrology. We then examine how these properties are linked to climate, resulting in a set of mechanisms whereby climate change can have pronounced impacts on lakes. Throughout this review, we have drawn on examples from both polar regions. Lake ecosystems are an important part of the Arctic landscape and there are limnological similarities to Antarctica. In both regions permanently frozen soils exert a strong influence on catchment properties such as hydrological processes and geochemical interactions. Similarly in both regions, snow and ice cover are major controls on the structure and functioning of aquatic ecosystems. There is a long history of limnological research in high northern latitudes and much of this information is directly relevant to Antarctica. Current observations and model predictions indicate that the Arctic is much more sensitive to climate change and will continue to experience more rapid shifts in its temperature regime than Antarctica (Overland et al. 2004a, b). Much of the Subarctic and Arctic became ice-free in the early Holocene and the limnology and paleolimnology of northern lakes therefore provide a window into the potential future states of Antarctic lakes undergoing climate change. © 2006 Springer.