Monday, November 24, 2014
Above is one of three recently-posted GigaPan images from October fieldwork at Quelccaya, with different depictions of the ice cap's western margin (available here for browsers w/o Flash plug-in).
The image above is a 92° field of view with a relatively short focal length (42 mm), looking to the south. Virtually the entire landscape visible in the panorama was covered by ice during the late Holocene (e.g., 500 years ago or less), and most of the scene was buried only ~40 years ago. For example, the lake at 5,200 m elevation on the left-hand side began forming in ~1985 (Thompson et al., 2013). Along upper portions of the margin seen here (i.e., center of image) we have measured a retreat rate of ~10 m/yr over the past decade, in addition to thinning.
This panorama illustrates the extent to which the glacier controls local hydrology, which is also the case on a regional scale. Areas of bedrock scoured by ice often contain lakes, and areas of sediment deposition (i.e., moraines) are often responsible for development of wetlands upstream. Lakes, streams, and wetlands (bofedales) are all sustained by glacier meltwater, especially through the dry season months of June-August. Without water the landscape is dry and barren, as in this image. Throughout the Cordillera Vilcanota today, runoff from glaciers supports a tremendous biodiversity - of mammals, birds, reptiles, amphibians, insects and more.
Despite lower air temperature, the transient snowline elevation at Quelccaya progressively increases during the dry season, occasionally depressed by snowfall events. These panoramas were taken during the dry-to-wet season transition, as 2014-15 accumulation was getting underway (as shown here). By late October, the transient snowline had reached approximately 5,400 m, as can be seen above or more clearly in this image. Consequently, all portions of the glacier below this elevation lost mass during 2013-14, despite above-average accumulation at the summit.