Friday, October 20, 2017

At the summit: days #92-96 in the crater

This month we returned to Kilimanjaro's summit glaciers and automated weather stations, 14 months since our last visit (Aug. 2016). Yes, the changes were dramatic - everywhere we looked.

This post provides a few glimpses of the remaining ice, still incredibly beautiful. Once an initial inspection is done on recovered AWS data, a subsequent post will provide an overview.

Helping out on this fieldwork were Spencer and Chang'a (Fig. 1). This was both of their first times on the mountain and both brought new insights and questions, providing stimulating discussions during the ascent and in camps. Dr. Ladislaus Chang'a is Director of Research and Applied Meteorology at the Tanzania Meteorological Agency (TMA), and involved with the IPCC. He will be coordinating our new data- and information-sharing collaboration with TMA, hopefully as part of WMO's Global Cryosphere Watch.

As previous entries have mentioned, the past year has been drier than normal at the summit. Decreased albedo has resulted in considerable ablation of both vertical and horizontal surfaces. Indeed, ice loss at the surface caused an unprecedented number of ablation stakes to melt out, and the tipping of several instrument towers. With essential support from our Summit Expeditions (SENE) crew (photos here and here), the towers were reset after 4 nights camped at the summit (see Fig. 2 & 3) and everyone descended safely.

The Furtwängler Glacier provides one illustration of the speed with which glaciers are shrinking on the mountain (Fig. 6). Since February 2000, when Henry Brecher determined the glacier area from aerial photographs, more than 80 percent of this glacier has disappeared. A brief historical perspective on this glacier is available here. The linear rate of area decrease suggests that there will be nothing left of the Furtwängler by 2025.

Many thanks to longtime collaborator Thomas Mölg for helping to support this fieldwork!

Figure 1.  Spencer Hardy and Dr. Ladislaus Chang'a at Barafu Camp (4,670 m), our fifth night of the ascent.

Figure 2.  Looking west over the Northern Icefield. Visible instrumentation includes (left to right) a timelapse camera, high-accuracy temperature and radiation measurement (Climate Reference Network compatible), and the original AWS. Several ablation stakes are faintly visible in the area around the instruments. See next image for detail.

Figure 3.  Northern Icefield instrumentation site at ~noon, looking toward Uhuru Peak on left skyline (2 km distant). This cloud pattern represents typical diurnal development, with convection to the south and west, and rising up the Western Breach.

Figure 4.  Detail of Northern Icefield surface near the AWS, with small nieves penitentes formed since the 2017 long rain season. About 35 cm of the ablation stake is exposed. Between the penitentes is new snow from the previous evening. Also note the area of dirty ice to the right of the stake; the character of all glacier surfaces on Kilimanjaro is spatially heterogeneous and varies tremendously from year to year.

Figure 5.  Rapidly shrinking, east-end remnants of the Northern Icefield, likely once part of an ice body shown in image #95, here.

Figure 6.  The view north from near Uhuru Peak. Northern Icefield in the background, still 40+ meters thick, and the Furtwängler Glacier (foreground); Reusch Crater sloping up to the right. The Furtwängler ice area is 32 percent less than it was just two years ago (Sep. 2015). See image #115 here for the same view in 2013.

Figure 7.  The remaining ice of the former Eastern Icefield, ~1.5 km distant to the northeast.

Figure 8.  Upper Deckens Glacier near Uhuru Peak, one remnant of the former Southern Icefield. Compare with image #33 here from 2009, when the Decken and Kersten Glaciers were still connected. The upper sections of these dirty south-side glaciers provide dramatic evidence for the processes of both sublimation and melt.

Figure 9.  The upper Rebmann Glacier, not far from Stella Point. The recent break-up here has been rapid, associated (in part) with marginal lake formation and drainage; note several areas of buried ice. On the right-hand side of the image, note how the ice stratigraphy more-or-less parallels the slope, yet the ablation surface is nearly horizontal. Selecting sites to obtain ice samples for age dating of these glaciers, or for ice core drilling, is not a trivial issue.

Figure 10.  Looking east from camp, just after sunset. One of the views which keeps us going back!

1 comment:

  1. Beautiful pictures, all the pictures you shared in this post are amazing. Kilimanjaro is really a beautiful and adventurous place for enjoying.

    Climbing Mountain Meru