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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
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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 HealthNational 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
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
FOR
CIN
G (
W/m
**2)
CO2
CH4
N2O
TROP. O3
HALOS
AEROSOL
UNCERTAINTY
2.68
-0.23
-1.91
range used in analyses
CONSTANT-C WARMING COMMITMENTCONSTANT-Q WARMING COMMITMENT: DT2x AND QAER EFFECTS
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
2000 2050 2100 2150 2200 2250 2300 2350 2400YEAR
GLO
BA
L-M
EAN
TEM
PER
ATU
RE
CH
AN
GE
(deg
C)
DT2x = 1.5 degC
DT2x = 2.6 degC
DT2x = 4.5 degC
H
M
L
CONSTANT-E WARMING COMMITMENTCONSTANT-E WARMING COMMITMENT: DT2x AND QAER EFFECTS
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
2000 2050 2100 2150 2200 2250 2300 2350 2400YEAR
GLO
BA
L-M
EAN
TEM
PER
ATU
RE
CH
AN
GE
(deg
C)
DT2x = 1.5 degC
DT2x = 2.6 degC
DT2x = 4.5 degC
H
M
L
CONSTANT-C SEA LEVEL COMMITMENTCONST-Q SEA LEVEL RISE COMMITMENT: DT2x, QAER & MELT EFFECTS
0
10
20
30
40
50
60
70
80
90
100
110
2000 2050 2100 2150 2200 2250 2300 2350 2400YEAR
GLO
BA
L-M
EAN
SEA
LEV
EL R
ISE
(cm
)
DT2x = 1.5 degC; QAER = HIGH; MELT = LOW
DT2x = 4.5 degC; QAER = LOW; MELT = HIGH
H
M
L
KEY : DT2x = 1.5, 2.6, 4.5 degC
CONSTANT-E SEA LEVEL COMMITMENTCONST-E SEA LEVEL RISE COMMITMENT: DT2x, QAER & MELT EFFECTS
0
20
40
60
80
100
120
140
160
180
200
220
2000 2050 2100 2150 2200 2250 2300 2350 2400YEAR
GLO
BA
L-M
EAN
SEA
LEV
EL R
ISE
(cm
)
DT2x = 1.5 degC; QAER = HIGH; MELT = LOW
DT2x = 4.5 degC; QAER = LOW; MELT = HIGH
H
M
L
KEY : DT2x = 1.5, 2.6, 4.5 degC
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
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
4
1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
YEAR
RADIA
TIVE
FO
RCIN
G (
W/m
**2)
CO2
AEROSOLS
N2OHALOS
TROP O3CH4
SRES CARBON DIOXIDE (CO2) PROJECTIONS
(emissions and concentrations)
SRES DECADAL FOSSIL-FUEL CO2 EMISSIONS
0
5
10
15
20
25
30
35
40
1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100YEAR
FOSS
IL C
O2
EMIS
SIO
NS (
GtC
/yr)
A1 - REDB1 - BLACKA2 - GREENB2 - BLUE
MEAN - MAGENTA
SRES RANGE OF CO2 PROJECTIONS
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
1050
1100
1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100YEAR
CO
2 C
ON
CEN
TRA
TIO
N (
ppm
)
IPCC TAR GLOBAL-MEAN TEMPERATURE PROJECTIONS
MAGICC projections in the IPCC TARMAGICC projections in the IPCC 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
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0 1 2 3 4 5 6 7 8
1990-2100 TEMPERATURE CHANGE (degC)
PRO
BA
BIL
ITY
DEN
SITY
(de
gC**
-1)
AREA = 0.05 AREA = 0.0590% CONFIDENCE INTERVAL
1.7 4.9
SOURCES OF UNCERTAINTY IN GLOBAL-MEAN TEMPERATURE
CHANGE
KEY SOURCES OF UNCERTAINTY FOR GLOBAL-MEAN TEMPERATURE
(1) Future emissions (2) The climate sensitivity* (3) Heat flux into the ocean (4) Radiative forcing due to aerosols (5) Carbon cycle/climate feedbacks (6) 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 (T2x) pdfOcean mixing (Kz) pdfAerosol forcing pdfCarbon 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 T2x based on AOGCM results.
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0 1 2 3 4 5 6 7GLOBAL-MEAN TEMPERATURE CHANGE FROM 1990 (oC)
PRO
BA
BIL
ITY
DEN
SITY
((o C
)-1)
PROBABILISTIC PROJECTIONS OF GLOBAL WARMING
TAR RANGE
1990-2030
1990-2070
1990-2100
PROBABILISTIC PROJECTIONS FOR THE RATE OF FUTURE GLOBAL-MEAN WARMING
MAGICC projections in the IPCC TARMAGICC projections in the IPCC TAR
PDFs FOR DECADAL WARMING TRENDSPROBABILITY DENSITY FUNCTIONS FOR DECADAL TRENDS
0
1
2
3
4
5
6
7
8
-0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2
GLOBAL-MEAN TEMPERATURE TREND (degC/decade)
PRO
BABI
LITY
DEN
SITY
(de
cade
/deg
C) 1991-2000
2051-2060
2091-21002.6%
CONFIDENCE LIMITS FOR DECADAL WARMING TRENDSTREND UNCERTAINTIES AS PERCENTILES : SRES EMISSIONS
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
1991 2001 2011 2021 2031 2041 2051 2061 2071 2081 2091
DECADE (1991 = 1991-2000, etc.)
GLO
BAL-
MEA
N TE
MPE
RATU
RE T
REND
(deg
C/de
cade
)99%
95%
50% (=median)
5%
1%
Trend over 1900-1999
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
350
400
450
500
550
600
650
700
750
800
1990 2010 2030 2050 2070 2090 2110 2130 2150 2170 2190 2210 2230 2250YEAR
CO
2 C
ON
CEN
TRA
TIO
N (
ppm
)
WRE450
WRE550
WRE650
WRE750
P50 BASELINE
CONST EFOSS(2000)
KEY POINTS
CO2 CONCENTRATION STABILIZATION PATHWAYS
350
400
450
500
550
600
650
700
750
800
1990 2010 2030 2050 2070 2090 2110 2130 2150 2170 2190 2210 2230 2250YEAR
CO
2 C
ON
CEN
TRA
TIO
N (
ppm
)
WRE450
WRE550
WRE650
WRE750
P50 BASELINE
CONST EFOSS(2000)
(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
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
1990 2010 2030 2050 2070 2090 2110 2130 2150 2170 2190 2210 2230 2250YEAR
TOTA
L C
O2
EMIS
SIO
NS
(GtC
/yr)
WRE450
WRE550
WRE650
WRE750
P50 BASELINE
KEY POINTS CO2 EMISSIONS TO ACHIEVE STABILIZATION
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
1990 2010 2030 2050 2070 2090 2110 2130 2150 2170 2190 2210 2230 2250YEAR
TOTA
L C
O2
EMIS
SIO
NS
(G
tC/y
r)
WRE450
WRE550
WRE650
WRE750
P50 BASELINE
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
Except for the 450ppm case, emissions can rise substantially above present levels and still allow concentration stabilization to be achieved
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 PDFs : CO2 STABILIZATION
CONCENTRATION IS CONTROLLED BY WARMING LIMIT,
CLIMATE SENSITIVITY AND NON-CO2 FORCING
INPUT PDF FOR CLIMATE SENSITIVITY
0
0.1
0.2
0.3
0.4
0.5
0 1 2 3 4 5 6CLIMATE SENSITIVITY, T2x (degC)
PRO
BA
BIL
ITY
DEN
SITY
(de
gC**
-1)
INPUT PDF FOR GLOBAL WARMING LIMIT (from 2000)
0
0.1
0.2
0.3
0.4
0.5
0.6
0 1 2 3 4 5 6GLOBAL WARMING LIMIT (degC)
PRO
BA
BIL
ITY
DEN
SITY
(de
gC**
-1)
INPUT PDF FOR NON-CO2 FORCING
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
-1 0 1 2 3 4
NON-CO2 FORCING (W/m**2)
PRO
BA
BIL
ITY
DEN
SITY
(m**
2/W
)
CO2 CONCENTRATION STABILIZATION TARGET
0
0.0002
0.0004
0.0006
0.0008
0.001
0.0012
0.0014
0.0016
0.0018
0.002
0.0022
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
CO2 CONCENTRATION (ppm)
PRO
BABI
LITY
DEN
SITY
(pp
m**
-1)
HIGH SENSITIVITYHIGH NON-CO2
FORCING
LOW SENSITIVITY
LOW NON-CO2 FORCING
Median (536 ppm)
17%
LOW WARMING LIMIT
HIGH WARMING LIMIT
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 ADAPTATIONPDFs FOR DANGEROUS INTERFERENCE WARMING
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0 1 2 3 4 5 6
GLOBAL-MEAN WARMING FROM 2000 (degC)
PRO
BA
BIL
ITY
DEN
SITY
(d
egC
**-1
)
BASE CASE
WITH ADAPTATION
EFFECT OF NON-CO2 EMISSIONS REDUCTIONS
PDFs FOR NON-CO2 FORCING
0
0.2
0.4
0.6
0.8
1
1.2
1.4
-0.5 0 0.5 1 1.5 2 2.5 3 3.5
RADIATIVE FORCING (W/m**2)
PRO
BA
BIL
ITY
DEN
SITY
(m
**2/
W)
BASE CASE
REDUCED EMISSIONS
REVISED PDF FOR TARGET CO2 LEVELSTAB TARGET PDFs : EFFECTS OF ADAPTATION AND NON-CO2 REDUCTIONS
0
0.0002
0.0004
0.0006
0.0008
0.001
0.0012
0.0014
0.0016
0.0018
0.002
0.0022
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
CO2 CONCENTRATION TARGET (ppm)
PRO
BA
BIL
ITY
DEN
SITY
(pp
m**
-1)
BASE CASE
ADAPTATION
NON-CO2 REDUCTIONS
BOTH
370
HOW WILL CO2 STABILIZATION AFFECT FUTURE GLOBAL-MEAN
WARMING?
EFFECTS OF CO2 STABILIZATION ON TEMPERATURE PDFsNO-POLICY, WRE450 AND WRE550 PDFs
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 1 2 3 4 5 6 7
1990 to 2100 GLOBAL-MEAN TEMPERATURE CHANGE (degC)
PRO
BABI
LITY
DEN
SITY
(de
gC**
-1)
NO POLICY (SRES)
450ppm CO2 STABILIZATION
550ppm CO2 STABILIZATION
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
0
10
20
30
40
50
60
70
80
90
2000 2050 2100 2150 2200 2250 2300 2350 2400
YEAR
GLO
BA
L-M
EAN
SEA
LEV
EL R
ISE
(cm
)
650
550
450
350
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 pathwaysCO2 CONCENTRATION STABILIZATION PROFILES
350
400
450
500
550
600
650
700
750
2000 2050 2100 2150 2200 2250 2300
YEAR
CO
2 C
ON
CEN
TRA
TIO
N (
ppm
)BASELINE (P50)
WRE450
WRE550
550 to 450
CH4 stabilization pathwaysCONCENTRATIONS FOR COST-EFFECTIVE METHANE EMISSIONS REDUCTIONS
500
750
1000
1250
1500
1750
2000
2250
2500
2750
2000 2050 2100 2150 2200 2250 2300 2350 2400
YEAR
MET
HA
NE
CO
NC
ENTR
ATI
ON
(pp
b)No-policy baseline (P50)
If CO2 target is 550ppm
If CO2 target is 450ppm(including overshoot case)
N2O stabilization pathwaysNITROUS OXIDE CONCENTRATIONS
310
320
330
340
350
360
370
380
390
400
410
2000 2050 2100 2150 2200 2250 2300 2350 2400
YEAR
N2O
CO
NC
ENTR
ATI
ON
(pp
b)No-policy baseline (P50)
If CO2 target is 550ppm
If CO2 target is 450ppm
(including overshoot case)
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
-1
0
1
2
3
4
5
6
7
8
9
10
11
2000 2050 2100 2150 2200 2250 2300 2350 2400
YEAR
FOSS
IL C
O2
EMIS
SIO
NS
(GtC
/yr)
WRE550
550 to 450
WRE450
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
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
2000 2050 2100 2150 2200 2250 2300 2350 2400
YEAR
GLO
BA
L-M
EAN
TEM
PER
ATU
RE
(deg
C)
WRE550
550 to 450
WRE450
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
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
2000 2050 2100 2150 2200 2250 2300 2350 2400
YEAR
GLO
BA
L-M
EAN
SEA
LEV
EL R
ISE
(cm
)WRE550
550 to 450
WRE450
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
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
0.22
0.24
0.26
0.28
2000 2050 2100 2150 2200 2250 2300 2350 2400
YEAR
WA
RM
ING
RA
TE (
degC
/dec
ade)
WRE550
550 to 450
WRE450
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
(per 1oC global-mean warming)
Normalized annual-mean temperature and precipitation changes in CMIP2 1%/year CO2 increase experiments
Normalized temperature change
Normalized precipitation change
-12.5
-10
-7.5
-5
-2.5
0
2.5
5
7.5
10
12.5
15
Longitude_pr
Latitu
de_p
r
-180 -120 -60 0 60 120-90
-70
-50
-30
-10
10
30
50
70
90
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
2.25
2.5
2.75
3
3.25
Longitude_tas
Latitu
de_ta
s
-180 -120 -60 0 60 120-90
-70
-50
-30
-10
10
30
50
70
90
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
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7
NORMALIZED TEMPERATURE CHANGE (degC/degC)
NO
RM
ALI
ZED
PR
ECIP
ITA
TIO
N C
HA
NG
E (%
/deg
C)
Sth. CA: 30 to 35N, 115 to 120W
Model mean
CCC1BMRC
GISS
CCSR
PCMCSM
HadCM2
ECHAM3
ECHAM4
HadCM3
GFDL
CSIRO2
MRI
W&M
LMD
IAP
CERF
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