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World and Asia climate change:
Assessment results by IPCC and
Japanese supercomputer model
predictions
LA of AR4 WG1 Chapter 5:
Observations: Oceanic Climate Change
and Sea Level
National Institute for Environmental Studies
Center for Global Environmental Research
Yukihiro NOJIRI
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AR4 Publication (Nov.21, 2007)

WG1 The Physical Science Basis,
published and pdf available from
IPCC web

WG2 Impacts, Adaptation and
Vulnerability, pdf available from
IPCC web

WG3 Mitigation of Climate Change,
pdf available from IPCC web
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NIES Contribution to IPCC AR4

5 Lead Authors and 1 Reviewing Editor for
the 3 WGs
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WG1: Y. Nojiri (LA) and contributors
WG2: H. Harasawa (CLA), K. Takahashi (LA), S.
Nishioka (RE) and contributors
WG3: M. Kainuma (LA), S. Hashimoto (LA) and
contriutors
NIES research field covers the whole aspect of
climate change sciences
We have 4 groups of climate change research;
carbon cycle, satellite observation, modeling,
socio-economic study.
IPCC Web Page
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AR4 is based on the direct obs.
of recent climate change
Since the TAR (3rd assessment report),
progress in understanding how climate is
changing in space and in time has been
gained through:
 improvements
and extensions of
numerous datasets and data analyses
 broader geographical coverage
 better understanding of uncertainties,
and
 a wider variety of measurements
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Global mean temperatures are
Warmest 12 years:
1998,2005,2003,2002,2004,2006,
rising faster with
time
2001,1997,1995,1999,1990,2000
Period
Rate
50 0.1280.026
100 0.0740.018
Years /decade
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Annual averages of the global
mean sea level
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Averaged global sea
level rise for 19612003 is 1.8mm/y.
Rising rate
increased to 3.1
mm/y for 19932003.
Sea level rise in
20th century is
estimated as 0.17m.
1961～2003：1.8±0.5mm/y
1993～2003：
3.1±0.7mm/y
17cm rise in 20th century
20th century: 1.7±0.5mm/y
Red: reconstructed sea level after 1870
Blue: tide gauge observed sea level after 1950
Black: sea level based on satellite altimetry
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Land precipitation is changing over broad areas
Increases
Decreases
Smoothed annual anomalies for precipitation (%) over land
from 1900 to 2005; other regions are dominated by variability.
Global-average radiative forcing
estimates and ranges
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Recent atmospheric CO2
change
atmospheric CO2
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Atmospheric CO2 is
increasing relating to the
fossil fuel emission rate.
Atmospheric oxygen
gives constraint for
estimating terrestrial and
oceanic CO2 sinks.
Atmospheric C isotope
change is one of strong
evidence of
anthropogenic emission.
oxygen/nitrogen ratio
fossil fuel emission
C isotope change
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How to project the future?
1. How will the world socioeconomic conditions develop?
2. How much GHGs will be emitted
from the society?
3. How much GHGs will be
accumulated in the atmosphere?
4. How will the climate change due
to increased atmospheric
GHGs?
5. How will the climate change
affect human society and
ecosystem?
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How will the climate change due to
the increased atmospheric GHGs?
‘Climate Model’ = a climate in a computer
Discretize atmosphere,
ocean, land into ‘grids’
Solve equations of physical
principles that govern climate
du 
u tan  
1
p
 f 

v  
dt 
a 
 a cos  
dT
d
p

dt
dt
．．．
cv
Define physical quantities
(wind, temp, ..) at each grid
Q
F
The “Earth Simulator”
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©JAMSTEC
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Climate model and resolution
©JAMSTEC
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Weather forecast is solved from the initial condition,
therefore it is impossible to project more than a week or so.
4/18(initial)
4/19(forecast)
4/20(forecast)
B
B
B
A
A
A
4/21(forecast)
4/22(forecast)
B
B
C
Weather chart from JWA
4/23(forecast)
C
D
C
Averaged feature of weather (i.e. climate) not depends16
on the initial condition, therefore an ensemble run from
many initial conditions can represent future climate.
100 yr projection of Japanese Jan. temperature from 3 initial conditions
The difference of initial conditions give different inter-annual
variability, however, the trend (e.g. 100 year average of
temperature increase) is very simillar.
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Why the prediction of temperature
rise (climate sensitivity) is difficult?
Feedback
Radiative
forcing
Temperature
rise
Changes in
vapor, snow-ice,
cloud …
The magnitude of feedback determines
climate sensitivity
Cloud feedback is especially uncertain
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How will the climate change due to
the increased atmospheric GHGs?
‘Climate Model’ = a climate in a computer
Descretize atmosphere,
ocean, land into ‘grids’
Solve equations of physical
principles that govern climate
du 
u tan  
1
p
 f 

v  
dt 
a 
 a cos  
dT
d
p

dt
dt
．．．
cv
Define physical quantities
(wind, temp, ..) at each grid
F
Q
Not purely derived from physical
principles (cloud, rain, radiation,
small-scale mixing, …)
↓
Half-empirically represented
(Source of uncertainty!)
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Simulated Temperature Change (1950-2100)
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Assessed ranges for surface warming
Scientific uncertainty
Scenario dependence
(IPCC, 2007）
Impacts of Climate Change
on Human Society
1. Agriculture
2. Water Resources
3. Human health
(Infectious diseases
and heat stress)
4. Coastal floods (Heavy
rainfall and high tide)
5. …
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Projections of Future Changes
in Climate

There is now higher confidence in
projected patterns of warming and
other regional-scale features,
including changes in wind patterns,
precipitation, and some aspects of
extremes and of ice.
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Frost days and heat waves

Extreme events like heat wave, draughts or floods
are likely to increase in the future climate.
Frost days (days of minimum
temperature of 0C)

decreasing
Winter warming may be more
significant than summer warming.
Heat waves (length of the period of
days of 5C higher than climatology)

increasing
Heat waves may increase globally,
especially Mediterranean and
Western North America.
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Change of precipitation
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Extreme events like heat wave, draughts or floods
are likely to increase in the future climate.
Precipitation intensity (annual total
precipitation/number of wet days)
Dry days (annual maximum of
consecutive dry day)
increasing
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Most of the area may have
increasing chance of heavy rain fall.
increasing
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Subtropical to mid latitude area may
have increasing chance of draught.
Climate change movies:
by Japanese Earth Simulator
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JAMSTEC/NIES/University of Tokyo Joint
Project
Climate Sensitivity of 4C/CO2 doubling,
which is within the higher sensitivity group
in the participated simulation models for
IPCC AR4 comparison
 Following simulation results are for A1B
scenario

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Global temperature increase
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Global precipitation change
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Sea surface temperature increase
Snow cover decrease
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Projection of 21th century climate change
for each continent from IPCC AR4 report
Projection for Asian climate
change from IPCC AR4 report
Figure 11.8
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Projection for Asian climate
change from IPCC AR4 report
Siberia
Central
Asia
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> global av. T
increase
Less
precipitation
Tibet
Japan
India
More
precipitation
Thailand
< global av. T
increase
Projection for Asian climate
change from IPCC AR4 report
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Robust findings on extreme precipitation
and draught from IPCC AR4 report
Box 11.1, Figure 2
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Hotspot of key vulnerabilities in Asia
from IPCC AR4 report Please check the WG2 report!
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Key vulnerabilities in Asia from IPCC AR4
report
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Southeast Asia will be vulnerable for Food and fibre, Biodiversity,
Coastal ecosystem, Human health and Land degradation by global
warming in 21th century
Central Asia is especially vulnerable for Water resource with very high
confidence and South Asia for Food and fibre