GC41A-0090
SPACE-BASED OBSERVATIONS OF BATURA GLACIER FLUCTUATIONS, WESTERN KARAKORAM HIMALAYA
Jack Shroder, M. Bishop, U. Haritashya, H. Bulley, J. Olsenholler, Department of Geography and Geology, University of Nebraska at Omaha, Omaha, NE 68182, jshroder@mail.unomaha.edu
ABSTRACT
Monitoring glacier variations by our GLIMS (Global Land Ice Measurements
from Space) Regional Center for Southwest Asia (Afghanistan and Pakistan)
shows unusual fluctuations over a 40-yr period for Batura Glacier. We use multiple field measurements (1984, 1991, 1992, 1993), maps and the work of others (1966, 1974, 1975, 1978, 1980), and satellite imagery (KH-9 Lower Resolution Mapping Camera 4/Aug/1973; Landsat MSS 15/Jul/1979; SPOT 20/
Jun/1990; Landsat 5 TM 15/Oct/1992; Landsat 7 ETM 29/Oct/2000 & 30/
Sep/2001; ASTER 29/Oct/2003 & 13/Sep/2004). The terminus was at the
Hunza River in late 19th and first half of 20th century and then retreated rapidly
~800 m by 1966, leaving behind prominent end moraines on the north terminus. Orthorectified declassified KH-9 imagery of 1973 shows variable widths
on Batura Glacier that were spurious and the result of preprocessing error.
Orthorectification was useful for point-to-point comparisons between multitemporal scenes, but not for within-scene comparisons or measurements. Batura does not surge and kinematic waves have not been detected. An ice cliff
had formed at the terminus in 1966, advanced forward 100 m and thickened by
15 m by 1975, and advanced another 33 m by 1978. Then instead of advancing
as predicted by Chinese scientists, by 1984 the frontal ice cliff had retreated 50100 m, declined in slope angle, and was covered with debris and vegetation,
which makes the slope still visible on recent imagery. Our orthorectified imagery shows that from 1973 – 2004 the front of the white ice stream from the
first ice fall on the right (south) side underwent retreat of ~2846 m, (retreat rate
of 92m yr-1), mainly through down-wasting increase of debris cover and new
melt-water lakes. Similarly the terminus underwent ~392 m of retreat from
1973 – 1990 (~23 m yr-1 annual retreat rate), ~36 m retreat from 1990-1992,
(~18 m yr-1 annual retreat rate), and a ~37 m advance (~3 m yr-1 annual advance rate) from 1992-2004. High-resolution imagery on Google Earth™ acquired in 2007 shows an exposed-ice terminus that has advanced ~50 m from
2004 on. A large new ice cliff has emerged on the southeast side ~ 275 m behind the present ice terminus, even while the parent south white-ice-stream
source continued to retreat up-ice. The Chinese Batura Glacier Investigation
Group used mass balance and tree-ring data in the 1970s to predict glacier advance from the 1970s, cessation in 1991 – 1997, and retreat for 20 – 30 years
thereafter. Global cooling was hypothesized with advances again by 2060, but
the actual situations have been otherwise. Glacier mass- balance regime
change is suggested by apparent increased summer monsoonal precipitation,
which falls as snow >~5000 m, and renewed terminus advance from beneath an
increasingly protective debris cover, even while the lowermost white-ice stream
continues to retreat through increased down-wasting during possible global
warming.
View of lower Batura Glacier in 1992 showing position of white ice stream that derives from the first
ice fall from Batura Muztagh. The up-ice retreat of the front of the white ice stream may reflect down
-wasting at lower altitudes.
ASTER Scene 13 September 2004. 1—Ice cliff. 2– Ice portal and Batura
River. 3– Farthest recent ice advance. 4– Red vegetation signature of
camel thorn on marginally stabilized terminus.
Overview of lower Batura Glacier from ASTER scene acquired 13 September 2004. Lower ice stream ogives pass down-ice into
reticulated ice hills before disappearing beneath increasing debris cover. The terminus region is blow up in the adjacent image.
By 1984, the bare ice cliff of 1974 was thinly covered with debris. The outflow channels of 1974, in the foreground of both these pictures, has been invaded
by camel thorn bushes and a kettle lake had developed that persists to the present.
This map, done for an unpublished summary paper of glacier-terminus changes, shows the 1966 and
1974 ice cliffs mapped by Chinese workers, as well as areas of active ice mapped by us. The changes
in the ice portal of the Batura river are shown, as well as other landforms. BI-Buried Ice; M-Moraine.
Precipitation and temperature reanalysis data for Hunza region (Batura Glacier—2o lat/long) generated using GCM climate simulations (European ERA40 climate model) constrained by regional climate-station data. These data can be produced on a monthly basis that show a new increase in summer monsoonal precipitation that falls as snow >~5000 meters. Note increasing precipitation
trend.
Conclusion:
Digital Globe Google Earth image 18 April 2007 of Batura Glacier terminus.
Glacier mass-balance regime changes may be occurring as a result of global warming wherein increases in summer precipitation reflect a change from winter westerly storms to summer monsoonal
storms. The enigmatic retreat of the white ice stream is perhaps a sensitive indicator of down-wasting but not of terminus changes, which may be more sensitive to overall increases of summer precipitation increase. Glaciers in the Western Himalaya and Karakoram are not melting away as are so many glaciers are in the Eastern Himalaya.
In 1993, much of the debris-buried ice of 1974 and earlier had been invaded by camel thorn. But from this view high on the valley side, melting ice can be
seen in the left center, with the ice portal of the Batura River out of site below the cliff.
Terminus retreat of the Batura Glacier from left bank of Hunza River according to Goudie, Jones, and
Brunsden (1984) as a result of the 1980 British IKP Expedition to Hunza.