Lake-catchment interactions with climate in the low Arctic of southern West Greenland

Arctic hydrology plays a central role in the earth’s heat balance and ocean circulation (Vorosmarty et al. 2001). Future changes associated with human influence on the climate system are also predicted to cause major changes in the energy and hydrologic mass balance of Arctic catchments. Climate change will likely affect permafrost and snowmelt, which dominate Arctic hydrology and control the chemistry of surface runoff (and hence streams and lakes) as water percolates through the active layer. However, the controls and dynamic impact of snowmelt are poorly understood, because this critical timeframe is often missed by sampling programmes. In the Sondre Stromfjord area only the broadest aspects of hydrologic variability have so far been documented (Hasholt & Sogaard 1976). Lakes respond to climatic forcing at a variety of timescales. For example, at relatively high frequencies (days), thermal stratification can be weakened or broken down by increased wind speeds associated with the passage of frontal systems. Seasonally, lake temperatures reflect annual changes in radiative heating and ambient air temperatures (Hostetler 1995). Year to year variability in climate can reduce the ice-free period (Magnuson et al. 2000; Doran et al. 2002). Over the longer term, (i.e. Holocene, hundreds to thousands of years) changes in the hydrological mass balance of