The geomorphology of the Green Lakes Valley (GLV), bound to the north by the crest of Niwot Ridge, is characteristic of alpine catchments in the Southern Rocky Mountains. The bedrock, relief and landforms of this landscape are the substrate on which the ecosystems studied at NWT have developed, and the geomorphic processes of weathering, erosion, sediment transport and deposition in themselves make up important ecosystem processes. Niwot Ridge and GLV have been the focus of considerable geomorphology research over the past 40 years, emphasizing the study of present-day processes and dynamics in alpine areas.
Subsurface ice preserved as ice lenses, within rock glaciers, and glacial and lake ice are sensitive indicators of climate change and serve as a late-season source of meltwater. Within the Green Lakes Valley (GLV), ice is permenantly present in the Green Lake 5 rock glacier and at other nearby favourable sites. Surface temperature measurements from rock glaciers in this area have not shown strong trends during the past 15 years (Leopold et al. 2015). However, the Arikaree Glacier in GLV has shown a marked decline in cumulative mass balance over the past 12 years. Seasonal lake ice duration has also decreased at all seven GLV lakes monitored during the last three decades (Fig. 1). Ice duration is most diminished at the lowest elevation lake, where it has decreased by about 1 d year^−1, and least diminished at the highest elevation lake (GL5), where the loss has been at a rate of 0.5 d year^−1. It has been suggested that almost all of the 2.5 mm year^−1 increase in stream discharge from the upper GLV in September and October has been derived from melting of subsurface ice.
This material is based upon work supported by the National Science Foundation under Cooperative Agreement #DEB-1637686. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necesarily reflect the views of the National Science Foundation.
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