C21B-01: Glaciers Response to Climatic Trend and Climate
Variability in Mt Everest Region (Nepal)
Sudeep Thakuri1,2,3, Franco Salerno1,3, Nicolas Guyennon1, Gaetano Viviano1,3,
Claudio Smiraglia2,3 , Carlo D’Agata2,3, Gianni Tartari1,3
1Water
Research Institute ̶ CNR, Brugherio; 2Graduate School of Earth, Environment and Biodiversity,
University of Milan, Milan; 3Ev-K2-CNR Committee, Bergamo, Italy. (Correspondence: [email protected])
3. Results and Discussion
1. Introduction
Mount Everest region in central southern
Himalaya, influenced by monsoondominated
climate
system,
is
characterized by dense debris-covered
glaciers (Scherler et al., 2011). Glaciers in
response to climate shows dynamic
behavior in terms of glacier morphology
and mass balance. Little efforts has been
put so far on studies on interdisciplinary
linkages of hydro-meteorological process
and glacier dynamics in the Himalaya.
The continuous retreatment of glaciers observed since 1960s to 2011 with
continuously increased rate. Majority of glaciers are retreating but some
glaciers are stationary or even advancing in some analysed periods. The
average terminus retreat of glaciers was about 400±34 m (8.2 m a-1) in
1962 to 2011 (Fig. 3A). The glacier surface area had loss of 13.0±3.4 % (0.27
% a-1) from 404.6 km2 to 351.8 km2 in 50 years with the loss by 0.13 % a-1 in
1962-75 to 0.57 % a-1 in recent years (Fig. 3B)
Accumulation zone
Debris-covered
ablation zone
Fig. 1. Upper part of Ngojumba
glacier (~98 km2).
We present glacier terminus, surface area, snowline altitude (SLA) and
debris-cover area change from 1960s to 2011 and climatic trends with the
aim of understanding coupled climate-glacier dynamics in the Sagarmatha
(Mt Everest) National Park (1148 km2) in Nepal Himalaya (Fig. 2).
AChina
ALOS- AVNIR-2, Acquisition 24 Oct 2008; Cloud cover: 0-2%
B
Mt Everest
(8848m)
India
D
AWS-KP
Gokyo
C
AWS1 & AWS-ABC
AWS2
Pheriche
Thame
AWS-NC
Namche
Automatic Weather Station (AWS)
Fig. 2. (A) Location of the study site in Nepal; (B) Enlarged 3D visualization of the
Sagarmatha (Mt. Everest) region (C) Area-elevation curve showing the glacier area
distribution in 2011; (D) Glacier extent change in 1962 and 2011.
2. Data and Method
Multi-temporal satellite imagery (Corona KH-4 1962, Landsat
MSS/TM/ETM+ (1975, 1992, 2000, 2011), ALOS/AVNIR-2 2008 and ASTERDEM with resolution ranging ~ 8 to 60 m), assisting by topo-maps (1950s,
1963 & 1992) and hydro-meteorologial data (temperature, precipitation
and river discharge) from stations were used. Time series for temperature
and precipitation reconstructed through the monthly quantile mapping and
expectation maximization techniques from 6 Automatic weather stations
located in the region. The singular spectral analysis (SSA) and monthly
sequential Mann-Kendall test (seqMK) were performed for trend analysis.
20
A
a1
Fig. 4. Evolution of morainedammed pro-glacier lake in the
terminus, one of the main cause of
glacier terminus retreat. A case of
Imja lake evolution since 1962 to
2011. The debris-covered ablation
zone of the glaciers in these region
are characterized by a large
number of supraglacier lakes
Using the Kuhn’s Climate- ELA model (Roger, 2005; Kayastha & Harrison,
2008), we estimated that for observed 182 m upward shift of the
snowline, a temperature increase of 1.1 °C or 535 kg m-2 of precipitation
decrease or 1.78 MJ m-2 d-1 of solar imbalance increase is required.
The temperature has increased by +0.6°C and the precipitation has
decreased by around 100 mm in last two decades (Fig. 5A-B). Both
temperature and precipitation trend are statistically significant for premonsoon and winter months. The longest and closed time series of
temperature and precipitation from Kathmandu station also agree with
this observation, indicating increase of temperature by 0.44/decade in
1961-2011 (Fig. 5D), while the precipitation has statistically no significant
trend until 1990s, but significantly weakening trend in 1990s to 2011.
The stream-flow data (Fig. 5C) indicates significantly widening of annual
(a1)
(b1)
(a2)
(b2)
(a3)
(b3)
(c1)
(d1)
A
B
-40
-60
1962-75
ΔTerminus (m)(m)
ΔTerminus
The SLA, a measure of ELA (Rabatel et al., 2012) and a proxy for the climate
change ( McFadden et al., 2011), was continuously moving upward (Fig. 3C)
from 5289 m a.s.l. (σ=139) in 1962 to 5471 m a.s.l. (σ=170) in 2011 with the
overall vertical shift of 182±8 m (3.7 m a-1). The rate of SLA shift was the
highest in recent years with the rate of 10.6±2.9 m a-1 a.s.l. The continuous
upward shift of the snowline indicates the negative mass balance.
-20
glacier terminus(m
change,
ΔTerminus
a-1)m yr
-1
0
a3
The smaller glaciers with <1 km2 dimension had decreased by 43 % in their
surface area showing rapid disappearance of small glacier/ice. The
accumulation area decreased by 24.8 %, whist ablation area increased by
17.7 % with about 17.6 % increase in debris-covered area in ablation zone
(~ 6 % net increase) from 1962 to 2011 (Fig. 3D).
-50
1975-92
1992-00
2000-08
2008-11
1962-11
a2
-150
-250
-350
-450
1955
B
1965
1975
1985
1995
2005
2015
b1
D
C(c2)
(d2)
(c3)
(d3)
-6
-4
-2
0
glacier surface change,
ΔSurface
(% a-1%)yr-1
2
b3
1962-75
ΔSurface
ΔSurface (%) (%)
10
1975-92
1992-00
2000-08
2008-11
1962-11
b2
0
-10
-20
1955
1975
1985
1995
2005
2015
c1
c3
-10
0
10
20
SLA shift,
ΔSLA
(mm yra-1-1)
30
40
C
1965
1962-75
ΔSLA (m)(m )
ΔSLA
200
150
1992-00
2000-08
1985
1995
2008-11
1962-11
c2
100
50
0
1955
1965
1975
2005
2015
d1
d3
-4
-2
0
2
4
4. Conclusion and Perspectives
1962-75
ΔDebris-cover
ΔDebris-cover (%) (%)
minimum and maximum discharges, with stationarity in overall trend until 2000 and than,
increased trend with two separate pre-monsoon and monsoon peaks. Our observations of
terminus and surface are lower than most of the previously reported values from the eastern,
western Himalaya and Tibetan plateau. These differences in variation of glaciers could be
explained by the distribution of debris-cover of glaciers. The glaciers in the central southern
Himalaya are heavily debris-covered than other parts of the Himalaya (Scherler et al., 2011).
6
8
D
debris-cover area change,
ΔDebris-cover
(%%ayr-1-1)
1975-92
Fig. 5. SeqMK test and SSA for (A) temperature, (B) precipitation, (C) downstream discharge, and (D) Kathmandu
temperature. In (A&B), upper first plot is SSA trend whereas in (C&D), upper first plot is annual trend. For all the
variables, middle plot is monthly SeqMK trend and third, for trend of Sen’s slope coeff. The asterisk shows the
significance of trend.
20
1975-92
1992-00
2000-08
1985
1995
2008-11
1962-11
d2
10
0
-10
1955
1965
1975
2005
2015
Fig. 3. Spatio -temporal changes of glacier terminus (A),
surface area (B), snowline altitude (C) and debris-covered
area (D) from 1962 to 2011. In the upper left panel, boxplot
represents variation occurred among glaciers (red points are
mean) in each analysed period while in the lower panel,
cumulative changes with associated uncertainty. In the
right side, the map shows spatial variation of glaciers.
The observed variation of glacier surface and SLA changes could be explained by the increase of
temperature and more importantly, by changes of precipitation in recent years but more analysis
is still required. We will explore the climate-glacier relationship by further more analysis of the
climate variables with the aim of integrating the glaciological, hydrological and climatic data for
understanding of future water availability scenario.
References:
Hooke, R.L. Principles of Glacier Mechanics, Cambridge University Press, p. 429 (2005).
Kayastha, R.B. & Harrison, S.P. Annals of Glaciology, 48:93-99 (2008).
McFadden, E. M., Ramage, J., and Rodbell, D. T. The Cryosphere, 5(2): 419-430 (2011).
Rabatel, A., Bermejo, A., Loarte, E., Soruco, A., Gomez, J., Leonardini, G., Vincent, C., and Sicart, J. E. Journal of Glaciology, 58(212): 1027–
1036 (2012).
Scherler, D., Bookhgen, B., and Strecker, M.R. Nature Geoscience, 4(3):156-159 (2011).