Glacier shrinkage in the Himalayas

under the monsoon climate

with the abundance of debris and dirt

NAKAWO, Masayoshi

National Institutes for the Humanities

1974 1994 1998

1978 1989 1998

Rikha Samba Glacier, Mukut Himal, Nepal

AX010 Glacier, Shorong Himal, Nepal

Mass 　 balance of world glaciersRikha 　 Samba Glacier

AX010 Glacier

Yala Glacier

Gla

cie

r su

rfac

e lo

we

ring

, mWhy the rate of shrinkage is

so large in the Himalayas?

① The warming rate is large?

② Other reason?

By Fujita

- 1

- 0.5

0

0.5

1

1900 1920 1940 1960 1980 2000

Tree Ring

Ice Core

The warming can be identified in the Himalayas, but the rate is not as pronounced, when compared with the rate at the other part of the world (roughly 0.7 to 0.8 degree/century), although the rate of glacier shrinkage is significantly large.

By Sano et al.

By Thompson et al.

Dai

ly T

empe

ratu

re,

deg

C

Dai

ly P

reci

pita

tion,

mm

OND JFM AMJ JAS

Observation of temperature and precipitation

made at the Rikha Samba Glacier, Mukut Himal, Nepal

Nepal

Tibet

Air Temperature, Deg C

Sno

w F

all p

roba

bilit

y, %

By Fujita et al.

Mon

thly

Pre

cipi

tatio

n, m

mComparison between glaciers fed during summer and winter, with the help of a glacier mass balance model, which takes into account the surface albedo.

Summer accumulationWinter accumulation

By Fujita et al.

Mass Balance, mm

Ele

vatio

n, m

Summer Type

Winter Type

Observation

If snow accumulates in winter, with completely the same total amount, the equilibrium line altitude becomes significantly higher, than glaciers fed during summer.

By Fujita et al.

Sur

face

Lev

el,

mA

lbed

o

Summer type

Winter type

Observation

OND JFM AMJ JAS

Summer snow keeps the surface albedo high so that the melting is hindered.

This albedo effect is the major advantage of summer accumulation type glaciers located in the Himalayas.

By Fujita et al.

Summary• The rapid shrinkage of glaciers in the Himalayas

is not caused by a higher rate of warming but by

1) Precipitation: Snow 　→　 Rain

２） Albedo effect: high(snow) → low(ice)

3) Warming effect:

→ higher rate of ablation

Therefore, the rapid shrinkage is caused by the fact that glaciers are fed during summer owing to the monsoon climate.

Monsoon

Yala Glacier, Langtang Himal, NepalAnother possible cause for the rapid shrinkage of Himalayan Glaciers : Biological activities

Yala Glacier, Lantang Himal

Cryoconite hole

Formation of Cryoconite ：　 Wisdom of the creatures who decide to live on glaciers

0

50

100

150

200

250

300

350

チベット ヒマラヤ パタゴニア アラスカ 北極

/

汚れ物質の量（乾燥グラム

平方メートル）

Tibet Himalaya Patagonia Alaska Arctic

Am

ount

of

dirt

mat

eria

ls,

dry

wei

ght,

g/m

2

Great abundance of Cyanobacteria over Himalayan glaciers could have caused the rapid shrinkage.

Third Pole region

By Takeuchi

Khumbu Himal, Nepal

0

1

2

3

4

5

6

0 2000 4000 6000 8000 10000(m)末端からの距離

(m/y

r)融

解速

度

Distance from the terminus, m

Mel

t rat

e, m

/aMelting of debris-covered ablation area, Khumbu Glacier

Glacier ice, even under a thick debris cover, has melted at a rate of about 1 m/a as an average.

Thick debris cover

of 0.5 to 2 m or more

Mass 　 balance of world glaciersRikha 　 Samba Glacier

AX010 Glacier

Yala Glacier

Gla

cie

r su

rfac

e lo

we

ring

, m

Debris-covered glacier (Khumbu)

Debris covered large glaciers have also shrunk at a high rate in the Himalayas.

Rapid deterioration of debris covered glaciers has lead to the formation of glacier lakes, and Glacier Outburst Flood with the failure of the dam bank.

Annual Precipitation, mm

Cha

nge

in a

nnua

l bal

ance

, m

Winter type

Summer type

Dongkemadi Glacier

Oerlemans’s estimation

Glaciers of summer accumulation type is more vulnerable to a warming climate than those of winter accumulation type.

This is considered the main cause for the rapid shrinkage of Himalayan glaciers during the recent warming climate.

With a warming experiment,

By Fujita et al.

4800

4900

5000

5100

5200

5300

5400

0 2000 4000 6000 8000 10000

x：流動方向に沿った水平距離　(m)

標高

　(m

)

1978測量1999測量1978

1999

2020

2040

2060

基盤

Distance along the flow direction, m

Ele

vati

on

, m

With　further　warming,　glacier　lake　could　form　near　the　terminus　of　debris-covered　glaciers.

By Naito et al.

Acceleration of glacier melt 　→　 Disappearance of glaciers

Formation of cryoconite is one of the styles of the adaptation of the living creatures on glaciers

Their wisdom, in association with the warming,

They would lose their home → 　 extinction ！

Human beings decided to live on earth and acclimatized with the environment.

We have triggered a rapid warming of global scale.

Warming proceeds, 　→　 deterioration of environment

Should we not be able to adapt, → 　 extinction ！