The global distribution of lakes is much higher in northern latitudes partly due to vast regions of permafrost terrain that form lakes (Figure 1). In Arctic regions underlain by permafrost, the climate is changing more rapidly and there is much interest in how vast numbers of lakes are responding to these changes. The CALON (Circum-Arctic Lakes Observation Network, www.arcticlakes.org) project begins to address this need by systematically collecting baseline datasets from lakes across Arctic Alaska landscapes using year-round sensor networks, synoptic sampling campaigns in the late winter and mid-summer, and remote sensing. The inclusion of winter monitoring adds new understanding to how these ecosystems are responding to the dominant season of the Arctic in which climate and lakes are also changing most rapidly (Figure 2), but previous data and investigation are limited.

The advantage of coupling multiple observation approaches in this project is exemplified by high resolution mapping of lakes that freeze solid and those that retain liquid water through the winter (Figure 3). This analysis coupled synthetic aperture radar (TerraSAR-X) image acquisition with a field campaign by snowmachine to validate these satellite measurements with geophysical techniques and ice drilling in one of our study regions where lakes provide important winter resources for petroleum exploration and also overwinter habitat for fish.  Another example of the power of coupling observation approaches during this project is in the detection of a catastrophic lake drainage event using satellite remote sensing and sensor networks (Figure 4). Such lake drainage events occur naturally, but the sheer numbers of lakes in the Arctic have made understanding this process elusive. Carefully designed study and on the ground presence allowed our project to directly record the causes and consequences of this event, and thus improve concepts of what drives this important landscape process and how floods generated from lake drainage can impact downstream freshwater systems. Environmental observation programs, such as CALON, that employ study designs with field presence during multiple seasons and realtime monitoring capability are essential for making such discoveries.

Acquiring year-round lake temperature and water level data from over 50 lakes arrayed across the Alaskan North Slope provided the core baseline information for his project. These data are archived with the Advanced Cooperative Arctic Data and Information Service (ACADIS) for other scientists, resource managers, and the general public to access. Our team has already used these datasets to answer questions about how lake ice-out timing varies by lake and with changing climate and provides a linkage to evaporation rates (Figure 5). Understanding this relationship between winter ice growth, lake depth, and water balance has implications for how regional hydrology, water supply, and habitat for fish, waterbirds, and other organisms will respond to changing Arctic climate.  Lake temperature at the water-sediment interface (lake bed) and measured maximum ice thickness data were also used to develop new models to predict how lakes impact permafrost. Applying this model to historic records at Barrow, AK suggest that permafrost is already beginning to thaw below shallow lakes, whereas warming in deeper lakes is much slower and changes in terrestrial permafrost is rapid, but still well below thawing thresholds at present (Figure 6). We expect that these and other CALON datasets will continue to be used to develop new models, serve as a baseline for future comparison, and improve our understanding of the Arctic where freshwater systems play a such a dominant role.  

Last Modified: 09/09/2016
Modified by: Christopher D Arp