2
The past climate,
variability and causes
The farther backward you can look,
the farther forward you are likely to see,
Winston Churchill
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
G,Plaut,M,Ghil
and R,Vautard,
(1995) Science,
268,710–713
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
Milankovitch theory
Milutin Milankovitch
(1879-1958)
Oil painting by Paja Jovanovic
in 1943 in Belgrade (Vasko
Milakovitch Collection,
Melbourne,Australia),
Definitions,
eccentricity
obliquity
precession
The eccentricity defines the shape or flattening of the orbit,
The obliquity measures the angle between the Earth's
axis of rotation and the perpendicular to the ecliptic,
Precession—the change in the direction of the Earth's
axis of rotation,i.e.,the axis of rotation behaves like the
spin axis of a top that is winding down; hence it traces a
circle on the celestial sphere over a period of time,
During one year the Earth is running along an quasi-elliptic orbit around
the Sun,The eccentricity of this orbit characterising its flattening is
slowly changing through time from 0 (a circle) to 6% at the maximum,
In this diagram the eccentricity has been largely exagerated to show how
the orbit is changing with eccentricity,the semi-major axis (a) being kept
constant,
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
Stadial and interstadial
Dansgaard-Oeschger cycle,~2-3ky
Heinrich event,~7-10ky
Bond cycle
Thermalhaline Circulation?
Simulated D/O and Heinrich events,
a,Forcing,b,Atlantic
overturning,c,Atlantic salinity
(S ) at 608 N,d,air temperature
in the northern North Atlantic
sector (60± 708 N),and e,
temperature over Antarctica
(temperature values are given as
the difference from the present-
day climate,DT ),Andrey
Ganopolski & Stefan Rahmstorf,
2001,Nature
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
Internal interaction among subsystems,
Ocean-atmosphere,Ice-atmosphere,…
External forcing,
Solar activity,human activity,…
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
Internal interaction among subsystems,
ocean-atmosphere,Ice-atmosphere,
land cover changes,atmospheric dynamics,…
External forcing,
volcanic eruption,solar activity,
human activity,…
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
1.8KaBP
1.0KaBP
Manabe and Stouffer,2000
Streamfunction of the THC in the Atlantic Ocean of coupled model in units
of sverdrups,(a) 100-year average control run,(b) FWN
Changes in surface temperature due to a collapse of the Atlantic
THC,as simulated by two CGCMs,(T F Stocker,Science,
2002)
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
Proxy data
Tree ring
Coral
Bore hole data
Ice core
Documental evidence
Other proxy data
Transfer function and pitfall
A "proxy" climate indicator is a local
record that is interpreted using
physical or biophysical principles to
represent some combination of climate-
related variations back in time,Only
proxy climate indicators have the
potential to provide evidence for large-
scale climatic changes prior to the
existence of widespread instrumental or
historical documentary records,
Delta 18O data series
extracted from a Tarawa
coral core,Julie Cole,2000
Rarotonga Island (
21.5° S,159.5° W)
NRC,1999
人吃人 蝗
水淹城门 大水
秋旱
春夏无雨
1 0 0 0 1100 1200 1300 1400 1 5 0 0 1600 1 7 0 0 1800 1900 2 0 0 0
- 1, 5
- 1, 0
- 0, 5
0, 0
0, 5
1, 0
1, 5 - 1 0 0
0
100
R
a
i
n
f
a
l
l
/
m
m
Y e a r
D
r
o
u
g
h
t
/
f
l
o
o
d
i
n
d
e
x (a ) W e t n e s s / dr y n e s s i n d e x
(b ) S u m m e r r a i n f a l l
w e t t e r
d r i e r
Decadally averaged Drought/flood Index (a) and
summer rainfall (b) anomalies for the mid-lower
valley Changjiang River,In curve a,the anomalies
are with respect to whole period AD1000-1999,
(Wang et al,2000)
8 00 9 00 1000 1100 1 2 00 1 3 00 1 40 0 1 50 0 1 60 0 17 0 0 18 0 0 19 0 0 2000
- 0,6
- 0,4
- 0,2
0,0
0,2
- 0,6
- 0,4
- 0,2
0,0
0,2
-0,6
- 0,4
- 0,2
0,0
0,2
(a)
(b)
(c )
近 1.2 ka中国东部（ a）、西部（ b）及全国（ c）
年平均气温对 20世纪的偏差（分辨率 50a）,虚
线为整个序列的平均值 (王绍武 等 2000)
Retreats and advances of an alpine glacier over the last
300 years [upper panel courtesy of Musée Alpin–Les
Amis du Vieux Chamonix],
Typically,the interpretation of a proxy climate record
is complicated by the presence of "noise" in which the
climate information is immersed with a variety of
possible distortions of the underlying climate
information,
Careful calibration and cross-validation procedures are
necessary to establish a reliable relationship between a
proxy climate indicator and the climatic variables to
determine an appropriate "transfer" function through
which past climatic conditions can be estimated,
High-resolution proxy climate indicators,including tree
rings,corals,ice cores,and laminated lake/ocean
sediments,can be used to provide detailed information on
annual or near-annual climate variations back in time,
Certain coarser resolution proxy information (from e.g,
boreholes,glacial moraines,and non-laminated ocean
sediment records) can usefully supplement this high-
The number of reconstructions or records required to estimate global-
scale temperature series to known accuracy versus the time scale of
interest,From P,D,Jones and K,R,Briffa,1996
The past climate,
variability and causes
The farther backward you can look,
the farther forward you are likely to see,
Winston Churchill
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
G,Plaut,M,Ghil
and R,Vautard,
(1995) Science,
268,710–713
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
Milankovitch theory
Milutin Milankovitch
(1879-1958)
Oil painting by Paja Jovanovic
in 1943 in Belgrade (Vasko
Milakovitch Collection,
Melbourne,Australia),
Definitions,
eccentricity
obliquity
precession
The eccentricity defines the shape or flattening of the orbit,
The obliquity measures the angle between the Earth's
axis of rotation and the perpendicular to the ecliptic,
Precession—the change in the direction of the Earth's
axis of rotation,i.e.,the axis of rotation behaves like the
spin axis of a top that is winding down; hence it traces a
circle on the celestial sphere over a period of time,
During one year the Earth is running along an quasi-elliptic orbit around
the Sun,The eccentricity of this orbit characterising its flattening is
slowly changing through time from 0 (a circle) to 6% at the maximum,
In this diagram the eccentricity has been largely exagerated to show how
the orbit is changing with eccentricity,the semi-major axis (a) being kept
constant,
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
Stadial and interstadial
Dansgaard-Oeschger cycle,~2-3ky
Heinrich event,~7-10ky
Bond cycle
Thermalhaline Circulation?
Simulated D/O and Heinrich events,
a,Forcing,b,Atlantic
overturning,c,Atlantic salinity
(S ) at 608 N,d,air temperature
in the northern North Atlantic
sector (60± 708 N),and e,
temperature over Antarctica
(temperature values are given as
the difference from the present-
day climate,DT ),Andrey
Ganopolski & Stefan Rahmstorf,
2001,Nature
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
Internal interaction among subsystems,
Ocean-atmosphere,Ice-atmosphere,…
External forcing,
Solar activity,human activity,…
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
Internal interaction among subsystems,
ocean-atmosphere,Ice-atmosphere,
land cover changes,atmospheric dynamics,…
External forcing,
volcanic eruption,solar activity,
human activity,…
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
1.8KaBP
1.0KaBP
Manabe and Stouffer,2000
Streamfunction of the THC in the Atlantic Ocean of coupled model in units
of sverdrups,(a) 100-year average control run,(b) FWN
Changes in surface temperature due to a collapse of the Atlantic
THC,as simulated by two CGCMs,(T F Stocker,Science,
2002)
1,Variability and mechanism
2,Glacial and interglacial cycles
3,Millennial variations
4,Holocene climate changes
5,Seasonal-interannual-decadal variations
6,Abrupt/rapid events
7,Reconstruction of the past climate
Proxy data
Tree ring
Coral
Bore hole data
Ice core
Documental evidence
Other proxy data
Transfer function and pitfall
A "proxy" climate indicator is a local
record that is interpreted using
physical or biophysical principles to
represent some combination of climate-
related variations back in time,Only
proxy climate indicators have the
potential to provide evidence for large-
scale climatic changes prior to the
existence of widespread instrumental or
historical documentary records,
Delta 18O data series
extracted from a Tarawa
coral core,Julie Cole,2000
Rarotonga Island (
21.5° S,159.5° W)
NRC,1999
人吃人 蝗
水淹城门 大水
秋旱
春夏无雨
1 0 0 0 1100 1200 1300 1400 1 5 0 0 1600 1 7 0 0 1800 1900 2 0 0 0
- 1, 5
- 1, 0
- 0, 5
0, 0
0, 5
1, 0
1, 5 - 1 0 0
0
100
R
a
i
n
f
a
l
l
/
m
m
Y e a r
D
r
o
u
g
h
t
/
f
l
o
o
d
i
n
d
e
x (a ) W e t n e s s / dr y n e s s i n d e x
(b ) S u m m e r r a i n f a l l
w e t t e r
d r i e r
Decadally averaged Drought/flood Index (a) and
summer rainfall (b) anomalies for the mid-lower
valley Changjiang River,In curve a,the anomalies
are with respect to whole period AD1000-1999,
(Wang et al,2000)
8 00 9 00 1000 1100 1 2 00 1 3 00 1 40 0 1 50 0 1 60 0 17 0 0 18 0 0 19 0 0 2000
- 0,6
- 0,4
- 0,2
0,0
0,2
- 0,6
- 0,4
- 0,2
0,0
0,2
-0,6
- 0,4
- 0,2
0,0
0,2
(a)
(b)
(c )
近 1.2 ka中国东部（ a）、西部（ b）及全国（ c）
年平均气温对 20世纪的偏差（分辨率 50a）,虚
线为整个序列的平均值 (王绍武 等 2000)
Retreats and advances of an alpine glacier over the last
300 years [upper panel courtesy of Musée Alpin–Les
Amis du Vieux Chamonix],
Typically,the interpretation of a proxy climate record
is complicated by the presence of "noise" in which the
climate information is immersed with a variety of
possible distortions of the underlying climate
information,
Careful calibration and cross-validation procedures are
necessary to establish a reliable relationship between a
proxy climate indicator and the climatic variables to
determine an appropriate "transfer" function through
which past climatic conditions can be estimated,
High-resolution proxy climate indicators,including tree
rings,corals,ice cores,and laminated lake/ocean
sediments,can be used to provide detailed information on
annual or near-annual climate variations back in time,
Certain coarser resolution proxy information (from e.g,
boreholes,glacial moraines,and non-laminated ocean
sediment records) can usefully supplement this high-
The number of reconstructions or records required to estimate global-
scale temperature series to known accuracy versus the time scale of
interest,From P,D,Jones and K,R,Briffa,1996
