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CLIMATE CHANGE PROJECTIONS:
SOURCES AND MAGNITUDES OF
UNCERTAINTY
Tom Wigley,
National Center for Atmospheric Research,
Boulder, CO 80307, USA
([email protected])
Presented at:
NCAR Summer Colloquium on Climate and Health
National Center for Atmospheric Research,
Boulder, CO.
July 22, 2004
OUTLINE OF TALK
Goal: To provide information about future
global-mean temperature and sea level
change and rates of temperature change, and
their uncertainties, for both no-climate-policy
and policy (concentration stabilization)
emissions scenarios.
OUTLINE OF TALK






Warming and sea level commitments
No-climate-policy projections (probability density functions
for temperature and rates of change of temperature)
CO2 concentration stabilization:
Concentration profiles and implied CO2 emissions
Article 2 and choosing a CO2 stabilization target:
Effects of adaptation and non-CO2 gases
Effects of CO2 stabilization on future warming and sea level
Multi-gas stabilization (CO2, CH4 and N2O)
Effects of CH4 and N2O on CO2 emissions, warming
and sea level
Future climate change depends on:
Perturbations already imposed on the climate
system (because of oceanic thermal inertia, the
effects of these perturbations have not yet been
fully realized); and
Perturbations we may impose in the future.
The latter depends on what policies we
introduce to limit future change.
FUTURE CLIMATE CHANGE: THREE CASES
(1) Changes already in the system –
the ‘warming commitment’
(2) ‘No climate policy’ emissions scenarios
(3) Policy (concentration stabilization) scenarios
CASE 1: WARMING COMMITMENTS (changes
already in the system)
(a) If we were able to stabilize atmospheric
composition at today’s (year 2000) level
[constant-C commitment]
(b) If we stabilized all emissions at today’s levels
[constant-E commitment]
COMMITMENT UNCERTAINTIES
….. are due to …..
(1) uncertainties in past natural and anthropogenic
forcing (mainly aerosol forcing)
(2) gas-cycle and climate model uncertainties …..
• carbon cycle feedbacks
•
•
climate sensitivity
ocean mixing
FORCING BREAKDOWN IN 2000
3
HALOS
2.5
TROP. O3
N2O
2
CH4
FORCING (W/m**2)
1.5
1
CO2
0.5
0
-0.23
-0.5
AEROSOL
-1
range used
in analyses
-1.5
-2
-1.91
UNCERTAINTY
2.68
CONSTANT-C WARMING COMMITMENT
CONSTANT-Q WARMING COMMITMENT: DT2x AND QAER EFFECTS
1
0.9
GLOBAL-MEAN TEMPERATURE CHANGE (degC)
0.8
DT2x = 4.5 degC
0.7
0.6
0.5
L
0.4
M
DT2x = 2.6 degC
H
0.3
0.2
DT2x = 1.5 degC
0.1
0
2000
2050
2100
2150
2200
YEAR
2250
2300
2350
2400
CONSTANT-E WARMING COMMITMENT
CONSTANT-E WARMING COMMITMENT: DT2x AND QAER EFFECTS
6
L
5.5
M
H
5
GLOBAL-MEAN TEMPERATURE CHANGE (degC)
DT2x = 4.5 degC
4.5
4
3.5
3
2.5
2
DT2x = 2.6 degC
1.5
DT2x = 1.5 degC
1
0.5
0
2000
2050
2100
2150
2200
YEAR
2250
2300
2350
2400
CONSTANT-C SEA LEVEL COMMITMENT
CONST-Q SEA LEVEL RISE COMMITMENT: DT2x, QAER & MELT EFFECTS
110
DT2x = 4.5 degC; QAER = LOW; MELT = HIGH
100
KEY : DT2x = 1.5, 2.6, 4.5 degC
GLOBAL-MEAN SEA LEVEL RISE (cm)
90
80
70
L
60
M
50
40
H
30
20
10
DT2x = 1.5 degC; QAER = HIGH; MELT = LOW
0
2000
2050
2100
2150
2200
YEAR
2250
2300
2350
2400
CONSTANT-E SEA LEVEL COMMITMENT
CONST-E SEA LEVEL RISE COMMITMENT: DT2x, QAER & MELT EFFECTS
220
DT2x = 4.5 degC; QAER = LOW; MELT = HIGH
200
KEY : DT2x = 1.5, 2.6, 4.5 degC
GLOBAL-MEAN SEA LEVEL RISE (cm)
180
160
L
140
M
H
120
100
80
60
40
20
DT2x = 1.5 degC; QAER = HIGH; MELT = LOW
0
2000
2050
2100
2150
2200
YEAR
2250
2300
2350
2400
CASE 2: CLIMATE CHANGE IN THE ABSENCE
OF CLIMATE MITIGATION POLICIES
PREDICTING FUTURE CLIMATE CHANGE
 Predict future socioeconomic changes
 Use these to predict future emissions
 From these predict changes in atmospheric
composition
 Use these results to drive a climate model
Question: How do we do this probabilistically?
[Results in this presentation use the MAGICC climate model. MAGICC can
be downloaded from www.cgd.ucar.edu]
THE SRES EMISSIONS SCENARIOS
(The basic drivers for future climate change)
The Intergovernmental Panel on Climate
Change (IPCC) has sponsored production of a
new set of ‘no-climate-policy’ emissions
scenarios for GHGs, sulfur dioxide, and other
gases
These scenarios are based on a range of
assumptions regarding future population,
economic growth, energy technology growth,
etc.
The scenarios are published in a Special Report
on Emissions Scenarios – hence the acronym
SRES
(Special Report on Emissions Scenarios, eds. N.Nakicenovic and
R. Swart, Cambridge University Press, 2000)
FUTURE EMISSIONS
IPCC SPECIAL REPORT ON EMISSIONS
SCENARIOS (SRES)
GASES CONSIDERED:
CO2
CH4
N2O
SO2
Reactive gases (CO, NOx, VOCs)
Halocarbons (CFCs, HCFCs, HFCs, PFCs, SF6)
RELATIVE IMPORTANCE OF
DIFFERENT GASES
FORCING CONTRIBUTIONS : A1B EMISSIONS
4
CO2
3.5
RADIATIVE FORCING (W/m**2)
3
2.5
2
1.5
1
AEROSOLS
0.5
HALOS
N2O
TROP O3
CH4
0
-0.5
1990
2000
2010
2020
2030
2040
2050
YEAR
2060
2070
2080
2090
2100
SRES CARBON DIOXIDE (CO2)
PROJECTIONS
(emissions and concentrations)
SRES DECADAL FOSSIL-FUEL CO2 EMISSIONS
40
35
A1 - RED
B1 - BLACK
A2 - GREEN
B2 - BLUE
FOSSIL CO2 EMISSIONS (GtC/yr)
MEAN - MAGENTA
30
25
20
15
10
5
0
1990
2000
2010
2020
2030
2040
2050
YEAR
2060
2070
2080
2090
2100
SRES RANGE OF CO2 PROJECTIONS
1100
1050
1000
CO2 CONCENTRATION (ppm)
950
900
850
800
750
700
650
600
550
500
450
400
350
1990
2000
2010
2020
2030
2040 2050
YEAR
2060
2070
2080
2090
2100
IPCC TAR GLOBAL-MEAN
TEMPERATURE PROJECTIONS
MAGICC
MAGICC projections
projections in
in the
the IPCC
IPCC TAR
TAR
PREDICTING FUTURE CLIMATE CHANGE
 Predict future socioeconomic changes
 Use these to predict future emissions
 From these predict changes in atmospheric
composition
 Use these results to drive a climate model
Question: How do we do this probabilistically?
A PROBABILISTIC PROJECTION IS ONE THAT …
quantifies uncertainties by …
(1) giving confidence intervals, or
(2) presenting results in the form of a probability
density function (p.d.f)
p.d.f. FOR GLOBAL-MEAN WARMING OVER 1990-2100
0.45
0.4
PROBABILITY DENSITY (degC**-1)
0.35
0.3
0.25
1.7
0.2
4.9
0.15
0.1
AREA = 0.05
AREA = 0.05
90% CONFIDENCE INTERVAL
0.05
0
0
1
2
3
4
5
1990-2100 TEMPERATURE CHANGE (degC)
6
7
8
SOURCES OF UNCERTAINTY IN
GLOBAL-MEAN TEMPERATURE
CHANGE
KEY SOURCES OF UNCERTAINTY FOR
GLOBAL-MEAN TEMPERATURE
(1)
(2)
(3)
(4)
(5)
(6)
Future emissions
The climate sensitivity*
Heat flux into the ocean
Radiative forcing due to aerosols
Carbon cycle/climate feedbacks
Changes in ocean circulation
* The climate sensitivity determines how much the climate will
change for a given change in atmospheric composition. It is usually
expressed as the eventual global-mean warming for a doubling of the
CO2 concentration, and lies in the range 1.5-4.5oC with approx. 90%
confidence.
INPUT REQUIREMENTS FOR PRODUCING
GLOBAL-MEAN TEMPERATURE PDFs
(from Wigley & Raper, Science 293, 451-454, 2001)
Emissions pdf (based on SRES)
Climate sensitivity (DT2x) pdf
Ocean mixing (Kz) pdf
Aerosol forcing pdf
Carbon cycle parameter pdfs
NOTE: Other climate model parameters are also altered (land-ocean sensitivity
ratio, exchange coefficients, THC slowdown rate), but the values are tied to DT2x
based on AOGCM results.
1.8
PROBABILISTIC PROJECTIONS OF GLOBAL
WARMING
1990-2030
1.4
o
-1
PROBABILITY DENSITY (( C) )
1.6
1.2
1
0.8
1990-2070
0.6
0.4
1990-2100
0.2
0
TAR RANGE
0
1
2
3
4
5
6
o
7
GLOBAL-MEAN TEMPERATURE CHANGE FROM 1990 ( C)
PROBABILISTIC PROJECTIONS
FOR THE RATE OF FUTURE
GLOBAL-MEAN WARMING
MAGICC
MAGICC projections
projections in
in the
the IPCC
IPCC TAR
TAR
PDFs FOR DECADAL WARMING TRENDS
PROBABILITY DENSITY FUNCTIONS FOR DECADAL TRENDS
8
1991-2000
PROBABILITY DENSITY (decade/degC)
7
6
5
4
3
2051-2060
2
1
2.6%
2091-2100
0
-0.2 -0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
GLOBAL-MEAN TEMPERATURE TREND (degC/decade)
1.1
1.2
CONFIDENCE LIMITS FOR DECADAL WARMING TRENDS
TREND UNCERTAINTIES AS PERCENTILES : SRES EMISSIONS
0.8
GLOBAL-MEAN TEMPERATURE TREND (degC/decade)
99%
0.7
95%
0.6
0.5
0.4
50% (=median)
0.3
0.2
5%
0.1
Trend over 1900-1999
0
1%
-0.1
1991
2001
2011
2021
2031
2041
2051
2061
DECADE (1991 = 1991-2000, etc.)
2071
2081
2091
CASE 3: CLIMATE MITIGATION POLICIES
ARTICLE 2 OF THE UNFCCC
Our objective should be …
“stabilization of greenhouse gas concentrations
in the atmosphere at a level that would prevent
dangerous anthropogenic interference with the
climate system ….. within a time-frame
sufficient to allow ecosystems to adapt naturally
to climate change, to ensure that food
production is not threatened and to enable
economic development to proceed in a
sustainable manner”.
POLICY CASES (CO2
CONCENTRATION STABILIZATION)
CO2 CONCENTRATION STABILIZATION PATHWAYS
800
WRE750
750
CO2 CONCENTRATION (ppm)
700
P50 BASELINE
WRE650
650
600
550
CONST EFOSS(2000)
WRE550
500
450
WRE450
400
350
1990 2010 2030 2050 2070 2090 2110 2130 2150 2170 2190 2210 2230 2250
YEAR
CO2 CONCENTRATION STABILIZATION PATHWAYS
800
WRE750
750
KEY POINTS
CO2 CONCENTRATION (ppm)
700
P50 BASELINE
WRE650
650
600
550
CONST EFOSS(2000)
WRE550
500
450
WRE450
400
350
1990 2010 2030 2050 2070 2090 2110 2130 2150 2170 2190 2210 2230 2250
YEAR
(1)
Stabilizing emissions does not stabilize
concentrations (magenta line in plot)
(2)
These concentration stabilization pathways
depart from the ‘no-policy’ baseline (black P50
line in plot) in 2005 (450ppm stabilization), 2010
(550ppm), 2015 (650ppm) and 2020 (750ppm)
(3)
A future departure date does not mean ‘do
nothing’ until then – it means setting in place now
the mechanisms for future (substantial) emissions
reductions below the no-policy case
EMISSIONS REQUIREMENTS FOR
CO2 CONCENTRATION
STABILIZATION
(Note: stabilization of emissions does not stabilize
concentrations, but leads to steadily increasing
concentrations – at around 100 ppm/century.)
CO2 EMISSIONS TO ACHIEVE STABILIZATION
18
P50 BASELINE
17
16
15
TOTAL CO2 EMISSIONS (GtC/yr)
14
WRE750
WRE650
13
12
11
WRE550
10
9
8
7
6
WRE450
5
4
3
2
1
0
1990 2010 2030 2050 2070 2090 2110 2130 2150 2170 2190 2210 2230 2250
YEAR
CO2 EMISSIONS TO ACHIEVE STABILIZATION
KEY POINTS
P50 BASELINE
17
16
15
14
TOTAL CO2 EMISSIONS (GtC/yr)
 Except for the 450ppm case,
emissions can rise substantially
above present levels and still
allow concentration stabilization
to be achieved
18
WRE750
WRE650
13
12
11
WRE550
10
9
8
7
6
WRE450
5
4
3
2
1
0
1990 2010 2030 2050 2070 2090 2110 2130 2150 2170 2190 2210 2230 2250
YEAR
 After peak emissions, rapid reductions in emissions are
required to achieve stabilization, implying a rapid
transition to non-fossil energy sources and/or a rapid
reduction in carbon ‘intensity’ (CO2 emissions per unit of
energy)
 Eventually, emissions must fall substantially below current
levels
 Note that these results are for CO2 alone – in practice the
effects of other greenhouse gases must also be accounted
for
WHAT SHOULD THE CO2
STABILIZATION TARGET BE?
(What does ‘dangerous
interference’ mean?)
[From Wigley, ‘Choosing a stabilization
target for CO2’, Climatic Change, in press]
INPUT PDF FOR GLOBAL WARMING LIMIT (from 2000)
PROBABILITY DENSITY (degC**-1)
INPUT PDFs : CO2
STABILIZATION
CONCENTRATION IS
CONTROLLED BY
WARMING LIMIT,
CLIMATE SENSITIVITY
AND NON-CO2 FORCING
0.6
0.5
0.4
0.3
0.2
0.1
0
0
INPUT PDF FOR CLIMATE SENSITIVITY
1
2
3
4
GLOBAL WARMING LIMIT (degC)
5
6
INPUT PDF FOR NON-CO2 FORCING
0.7
0.5
PROBABILITY DENSITY (m**2/W)
PROBABILITY DENSITY (degC**-1)
0.6
0.4
0.3
0.2
0.1
0.5
0.4
0.3
0.2
0.1
0
0
0
1
2
3
4
CLIMATE SENSITIVITY, DT2x (degC)
5
6
-1
0
1
2
NON-CO2 FORCING (W/m**2)
3
4
CO2 CONCENTRATION STABILIZATION TARGET
0.0022
Median (536 ppm)
0.002
PROBABILITY DENSITY (ppm**-1)
HIGH SENSITIVITY
0.0018
HIGH NON-CO2
FORCING
0.0016
LOW WARMING
LIMIT
0.0014
0.0012
0.001
LOW SENSITIVITY
0.0008
LOW NON-CO2
FORCING
0.0006
HIGH WARMING LIMIT
0.0004
0.0002
17%
0
0
100
200
300
400
500
600
700
800
900
1000 1100 1200 1300 1400 1500
CO2 CONCENTRATION (ppm)
WHAT CAN BE DONE TO RELAX
THE CO2 TARGET?
(….. AND SO REDUCE THE CO2 MITIGATION LEVEL
AND COSTS)
EFFECTS OF ADAPTATION AND NON-CO2
GASES
EFFECT OF ADAPTATION
PDFs FOR DANGEROUS INTERFERENCE WARMING
0.45
WITH ADAPTATION
PROBABILITY DENSITY (degC**-1)
0.4
0.35
0.3
BASE CASE
0.25
0.2
0.15
0.1
0.05
0
0
1
2
3
4
GLOBAL-MEAN WARMING FROM 2000 (degC)
5
6
EFFECT OF NON-CO2 EMISSIONS REDUCTIONS
PDFs FOR NON-CO2 FORCING
1.4
REDUCED EMISSIONS
PROBABILITY DENSITY (m**2/W)
1.2
1
0.8
0.6
0.4
BASE CASE
0.2
0
-0.5
0
0.5
1
1.5
2
RADIATIVE FORCING (W/m**2)
2.5
3
3.5
REVISED PDF FOR TARGET CO2 LEVEL
STAB TARGET PDFs : EFFECTS OF ADAPTATION AND NON-CO2 REDUCTIONS
0.0022
BASE CASE
0.002
NON-CO2 REDUCTIONS
PROBABILITY DENSITY (ppm**-1)
0.0018
0.0016
ADAPTATION
0.0014
BOTH
0.0012
0.001
0.0008
0.0006
0.0004
0.0002
370
0
0
100
200
300
400
500
600
700
800
900 1000 1100 1200 1300 1400 1500
CO2 CONCENTRATION TARGET (ppm)
HOW WILL CO2 STABILIZATION
AFFECT FUTURE GLOBAL-MEAN
WARMING?
EFFECTS OF CO2 STABILIZATION ON TEMPERATURE PDFs
NO-POLICY, WRE450 AND WRE550 PDFs
0.8
450ppm CO2 STABILIZATION
PROBABILITY DENSITY (degC**-1)
0.7
0.6
550ppm CO2 STABILIZATION
0.5
0.4
0.3
0.2
NO POLICY (SRES)
0.1
0
0
1
2
3
4
5
6
1990 to 2100 GLOBAL-MEAN TEMPERATURE CHANGE (degC)
7
EFFECT OF CO2 STABILIZATION ON SEA LEVEL
[WRE profiles; other gases follow median emissions to 2100, then constant emissions]
SEA LEVEL PROJECTIONS FOR STABILIZATION PROFILES
90
650
80
550
GLOBAL-MEAN SEA LEVEL RISE (cm)
70
450
60
50
350
40
30
20
10
0
2000
2050
2100
2150
2200
YEAR
2250
2300
2350
2400
THE IMPORTANCE OF NON-CO2
GASES
In the following, CO2, CH4 and N2O concentrations are
stabilized. The emissions reductions required to do this
are balanced between the gases in order to minimize
the total cost (‘cost optimization’). This is done using the
energy-economics model MERGE developed by
economists Alan Manne and Richard Richels
CO2 stabilization pathways
CO2 CONCENTRATION STABILIZATION PROFILES
750
BASELINE (P50)
700
CO2 CONCENTRATION (ppm)
650
600
WRE550
550
500
550 to 450
450
WRE450
400
350
2000
2050
2100
2150
YEAR
2200
2250
2300
CH4 stabilization pathways
CONCENTRATIONS FOR COST-EFFECTIVE METHANE EMISSIONS REDUCTIONS
2750
No-policy baseline (P50)
2500
If CO2 target is 550ppm
METHANE CONCENTRATION (ppb)
2250
2000
1750
1500
1250
1000
750
If CO2 target is 450ppm
(including overshoot case)
500
2000
2050
2100
2150
2200
YEAR
2250
2300
2350
2400
N2O stabilization pathways
NITROUS OXIDE CONCENTRATIONS
410
No-policy baseline (P50)
400
N2O CONCENTRATION (ppb)
390
380
If CO2 target is 550ppm
370
If CO2 target is 450ppm
360
(including overshoot case)
350
340
330
320
310
2000
2050
2100
2150
2200
YEAR
2250
2300
2350
2400
Reducing CH4 and (to a lesser extent)
N2O concentrations reduces future
warming and so reduces the magnitude
of climate feedbacks on the carbon
cycle.
As a consequence, the CO2 emissions
required to follow a given concentration
pathway can be higher than otherwise.
CO2 emissions: with CH4 and N2O reductions (full lines)
compared with the no CH4/N2O reduction case (dashed lines)
CO2 EMISSIONS WITH (BOLD) AND WITHOUT (DASHED) CH4/N2O REDUCTIONS
11
10
FOSSIL CO2 EMISSIONS (GtC/yr)
9
8
7
6
5
4
WRE550
3
2
WRE450
1
550 to 450
0
-1
2000
2050
2100
2150
2200
YEAR
2250
2300
2350
2400
TEMPERATURE AND SEA LEVEL RESULTS
Global warming: with CH4 and N2O reductions (full lines)
compared with the no CH4/N2O reduction case (dashed lines)
TEMPERATURES WITH (BOLD) AND WITHOUT (DASHED) CH4/N2O REDUCTIONS
3
2.8
GLOBAL-MEAN TEMPERATURE (degC)
2.6
2.4
2.2
2
WRE550
1.8
1.6
1.4
1.2
WRE450
1
550 to 450
0.8
0.6
0.4
0.2
0
2000
2050
2100
2150
2200
YEAR
2250
2300
2350
2400
Sea level change: with CH4 and N2O reductions (full lines)
compared with the no CH4/N2O reduction case (dashed lines)
SEA LEVEL WITH (BOLD) AND WITHOUT (DASHED) CH4/N2O REDUCTIONS
80
WRE550
75
70
GLOBAL-MEAN SEA LEVEL RISE (cm)
65
60
550 to 450
55
50
45
40
WRE450
35
30
25
20
15
10
5
0
2000
2050
2100
2150
2200
YEAR
2250
2300
2350
2400
Warming rate: with CH4 and N2O reductions (full lines) compared
with the no CH4/N2O reduction case (dashed lines)
dT/dt WITH (BOLD) AND WITHOUT (DASHED) CH4/N2O REDUCTIONS
0.28
0.26
0.24
WARMING RATE (degC/decade)
0.22
0.2
0.18
WRE450
0.16
0.14
0.12
0.1
0.08
WRE550
0.06
0.04
0.02
0
550 to 450
-0.02
-0.04
2000
2050
2100
2150
2200
YEAR
2250
2300
2350
2400
CONCLUSIONS 1: Commitments
Concentrations stabilized
0.11 to 0.48oC warming by 2050
sea level rises at 2–27cm/century
Emissions stabilized
warming at 0.8 to 2.0oC/century
sea level rises at 8–54cm/century
CONCLUSIONS 2: NO-POLICY
(1) 90% C.I. for 2000-2100 warming 1.5–4.7oC
(2) 90% C.I.s for warming rates …..
2050s: 0.16–0.65oC/decade
2090s: 0.02–0.58oC/decade
[cf. 20th century warming at 0.07oC/decade]
(3) 3% probability of cooling in the 2090s
CONCLUSIONS 3: STABILIZATION
(1) CO2 emissions must eventually drop well below present
levels
(2) Based on ‘dangerous interference’, there is a 17% chance
that the CO2 stabilization target should be less than the
present level (absent adaptation and non-CO2 emissions
reductions)
(3) Multi-gas concentration stabilization:
• CO2 emissions targets less stringent [for a given conc. profile]
• Asymptotic warming is reduced by almost 1oC
• Sea level rise is reduced by up to 15cm
• Maximum warming rate is reduced by 2% to16%
POST SCRIPT
Lead in to Nychka/Tebaldi
presentation.
RESULTS FOR PATTERNS OF
CLIMATE CHANGE
o
(per 1 C global-mean warming)
Normalized annual-mean temperature and precipitation
changes in CMIP2 1%/year CO2 increase experiments
90
70
Normalized
temperature
change
L a t it u d e _ t a s
50
30
10
-1 0
-3 0
-5 0
-7 0
-9 0
-1 8 0
-1 2 0
0
-6 0
0.5
0.25
0
Long itude_ta s
1.5
2
1
0.75
1.25
60
120
2.5
1.75
2.25
3
2.75
3.25
90
70
Normalized
precipitation
change
L a t it u d e _ p r
50
30
10
-1 0
-3 0
-5 0
-7 0
-9 0
-1 8 0
-1 2 0
-1 2 . 5
-6 0
-7 . 5
-1 0
-2 . 5
-5
0
Long itude_pr
2.5
0
60
120
7.5
5
12.5
10
15
MODELS GIVE A WIDE RANGE
OF RESULTS FOR PROJECTED
PRECIPITATION CHANGES
SPANNING THE RANGE OF POSSIBLE FUTURES
(blue = better models)
DJF PRECIP CHANGES vs DJF TEMP CHANGES (Control drift removed)
30
BMRC
CCC1
NORMALIZED PRECIPITATION CHANGE (%/degC)
25
20
HadCM2
15
10
MRI
5
PCM
CERF
CSM
0
IAP
ECHAM4
GISS
Model mean
-5
GFDL
LMD
-10
CSIRO2
W&M
-15
ECHAM3
-20
HadCM3
-25
Sth. CA: 30 to 35N, 115 to 120W
CCSR
-30
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
NORMALIZED TEMPERATURE CHANGE (degC/degC)
1.6
1.7
FURTHER INFORMATION
IPCC Third Assessment Reports published by
Cambridge University Press (see www.ipcc.ch).
These reports are quite technical. Summaries are
downloadable from the web site.
Pew Center on Global Climate Change
(www.pewclimate.org).
The Pew Center has published many plain language reports
on various facets of the global warming issue; downloadable.
The MAGICC (Global-mean temperature and sea
level)/SCENGEN (Regional details for temperature and
precipitation) software can be downloaded from …..
www.cgd.ucar.edu