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Precipitating Change: Holocene climate change in the Asian monsoon based on sediment archives from tropical lakes Roshni Sharma Masters of Applied Science School of Geosciences, University of Sydney
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Transcript of IsoEcol_RSharma_shorter1_20140708
Precipitating Change:
Holocene climate change in the Asian monsoon based on sediment archives
from tropical lakesRoshni Sharma
Masters of Applied Science School of Geosciences, University of Sydney
Thank you, thank you, thank you!Australian Research Council Discovery
Projects (DP1094367 )Cambodian Crater Lakes project collaborators:
D.A. Penny, University of SydneyB.M. Buckley, Columbia UniversityQ. Hua, ANSTO
Dr Andy Maxwell (Independent scholar, USA)Cambodian Ministry of EnvironmentANSTOAMMRF/ACMMAINSE travel scholarship for IsoEcol2014
Why?Understanding the Asian monsoon as a complex system
Responses over mainland Southeast Asia through the early Holocene ???
High resolution record of climate variability in the Asian tropics from the early Holocene from a direct climate proxy
Contribute to improvement of climate modelling / understanding of the earth systems as a complex
system
Oman
Tibetan Plateau
China
India
Cancer
Capricorn
Equator
Adapted from Black (2002: 528)
Summer
Winter
What does the literature say about the behaviour of the Asian monsoon through the Holocene?Oman Indian Summer
Monsoon
Gradual weakening
Strong summer monsoon
Tibetan Plateau
Indian Summer Monsoon / East Asian Summer monsoon
Gradual weakening
Asynchronous start
of weakening
Strong summer monsoon
South-west China
Indian summer monsoon / East Asian Summer monsoon
Gradual weakening
Strong summer monsoon
South China
East Asian Summer monsoon
Gradual weakening
Strong summer monsoon
Central China
East Asian Summer monsoon
Gradual weakening
Strong summer monsoon
Region
14C yr 1000 2000 3000 4000 5000 6000 7000 8000 9000
Cal yr BP 930 1940 3200
4400 5700 6800 7800
Strong summer monsoon
Strong summer monsoon
Strong summer monsoon
Strong summer monsoon
Strong summer monsoonGradual weakening
Gradual weakening
Gradual weakening
Gradual weakening
Gradual weakening
Asynchron-ous start of weakening
Cancer
Capricorn
Equator
Adapted from Black (2002: 528)
1. Are lake waters representative of regional climate?
2. How is climate recorded in lake sediment archives?
3. What does the direct climate proxy record say about the behaviour of the Asian monsoon system over mainland Southeast Asia in the early-mid Holocene?
1. Are lake waters representative of regional climate?
Yeak OamYeak Kara
Boeng LumkutYeak Loam
-2.50 -2.00 -1.50 -1.00 -0.50 0.00 0.500
5
10
15
20
25
30
35
40
Nov-11 Feb-12 Jul-12 Nov-12 Apr-13
δ18O (‰)
Dept
h (m
etre
s)Nov-1
1
Feb-12
Jun-12
Oct-12
Feb-13
-3.0
-2.5
-2.0
-1.5
-1.0
0
100
200
0 metres
δ18O (‰) amount rainfall (mL)
δ18
O (
‰)
rain
fall
(mL)
-3.0-2.5-2.0-1.5-1.0
10 metres
δ18
O (
‰)
-3.0
-2.5
-2.0
-1.5
-1.0
20 metres
δ18
O (‰
)
-3.0
-2.5
-2.0
-1.5
-1.0
30 metres
δ18
O (
‰)
-3.0-2.5-2.0-1.5-1.0
20 metres
δ18
O (‰
)
-3.0-2.5-2.0-1.5-1.0
40 metres
δ18
O (
‰)
Isotopic ratios of lake waters,
local meteoric waters, and the GMWL-15.00 -13.00 -11.00 -9.00 -7.00 -5.00 -3.00 -1.00
-120.00
-100.00
-80.00
-60.00
-40.00
-20.00
0.00f(x) = 8 x + 10R² = 1
f(x) = NaN x + NaNR² = 0f(x) = NaN x + NaNR² = 0
18O/2H rain waterLinear (18O/2H rain water)
δ18O (‰)
δ2H
(‰)
2. How is climate recorded in
lake sediment archives?
Authigenic inorganic calcium carbonate
Electron backscatter diffraction (EBSD)Description EBSD refraction pattern
Name Aragonite Database Inorganic Crystal Structure Database
Structure
Crystal System Orthorhombic
Shape
LaueGroup 3
Space Group 62
Unit Cell
a 5.74 Å
b 4.96 Å
c 7.97 Å
Alpha 90.00 °
Beta 90.00 °
Gamma 90.00 °
EBSD Phase map of calcium carbonate species
3. What does the direct climate proxy record say about the
behaviour of the Asian monsoon system over
mainland Southeast Asia in the early-mid Holocene?
Contribution of this study to the literature?
Oman Indian Summer Monsoon
Gradual
weakeningStrong summer
monsoon
Tibetan Plateau
Indian Summer Monsoon / East Asian Summer monsoon
Gradual weakening
Asynchron-ous start
of weakening
Strong summer monsoon
Mainland Southeast Asia
Indian summer monsoon / East Asian Summer monsoon
South-west China
Indian summer monsoon / East Asian Summer monsoon
Gradual weakening
Strong summer monsoon
South China
East Asian Summer monsoon
Gradual weakening
Strong summer monsoon
Central China
East Asian Summer monsoon
Gradual weakening
Strong summer monsoon
Region
14C yr 1000 2000 3000 4000 5000 6000 7000 8000 9000
Cal yr BP 930 1940 3200
4400 5700 6800 7800
Asynchron-ous start of weakening
Strong summer monsoon
Strong summer monsoon
Strong summer monsoon
Strong summer monsoon
Strong summer monsoon
Strong summer monsoon
Gradual weakening
Gradual weakening
Gradual weakening
Gradual weakening
Gradual weakening
Gradual weakening
How does this compare with a nearby record?
Comparison of broad trends in Donnge cave record (Wang et al., 2005) and Yeak Kara record of changes in the Holocene Asian monsoon. Both series are displayed with a three year moving average trend line
1.2 kaBP
5.0 90.0175.0
260.0345.0
430.0515.0
600.0685.0
0 100 200 300 400 500 600 700 800
4100
5100
6100
7100
8100
9100
δ18O (‰PDB) volcanic sulphate‰ PDB
Age
(yr B
P)
total sulphates (ppb)-20002004006008001000
4100
5100
6100
7100
8100
9100
δ18O (‰PDB) Jun mid-month insolation‰ PDB
Age
(yr B
P)
June mid-month insolation
GISP2 volcanic sulphates (Zielinksi & Mershon (1997), et al.)
Total solar irradiance (Berger & Loutre, 1991)
