Stabilizing Long-Term Temperature:
The Issues of Uncertainty, Timing,Costs and Technology
Richard Richels
Alan Manne
Tom Wigley

Greenhouse Gas Stabilization Scenario Workshop
National Institute of Environmental Studies
Tsukuba, Japan
22-23 January 2004

Issues
1. What is the range and likelihood of temperature change overthe 21st century in the absence of climate policy?
2. What is the impact of technological expectations on the least-costemission pathways for stabilizing global-mean temperature?
3. What is the impact of technological expectations on thenear-term price of carbon?
4. What is the potential value of a technology rich energy future?
5. Why focus on stabilizing temperature rather than concentrations?

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MERGE• An intertemporal CGE Model• 9 geopolitical regions• 150 year time horizon• Bottom-up representation of energy sector• Learning-by-doing (LBD)• Top-down representation of rest of economy• Multiple greenhouse gases• Aerosol cooling• Tradeoff among gases based on relative prices, not GWPs
• Climate module calibrated with MAGICC
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Electricity Generation Technologies
Identification/Examples

Availability Pessimistic
TechnologyScenario

Availability Optimistic
Technology
Scenario

Hydroelectric, geothermal and other renewables

yes

yes

Existing nuclear and fossil

yes

yes

Advanced combined cycle

yes

yes

New coal without CO2 recovery

yes

yes

Fuel cells with capture and sequestration

noyes

Integrated gasification and combined cycle with captureand sequestration

no

yes

Carbon-free technologies; costs do not decline with LBD

yes

yes

Carbon-free technologies; costs decline with LBD

noyes

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Nonelectric Energy Supplies
Description

Coal-direct uses
Oil
Gas
Coal-based synthetic fuelsRenewables
Carbon-free technologies; costs do notdecline with LBD
Carbon-free technologies; costs declinewith LBD

Availability Pessimistic
Technology
Scenario
yes
yes
yes
yes
yes
yes

Availability Optimistic
Technology
Scenario
yes
yes
yes
yes
yes
yes

no

yes

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Issues
1. What is the range and likelihood of temperature change overthe 21st century in the absence of climate policy?
2. What is the impact of technological expectations on the least-costemission pathways for stabilizing global-mean temperature?
3. What is the impact of technological expectations on thenear-term price of carbon?
4. What is the potential value of a technology rich energy future?
5. Why focus on stabilizing temperature rather than concentrations?

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Three Uncertainties• Income growth• Climate sensitivity• Temperature lag

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Potential Gross World ProductAnnualRate ofGrowth

600

Trillions of dollars

500

400

High (H)
Medium high (M-H)
Medium (M)Medium low (M-L)
Low (L)

300

200(%/year)

Probability

H

2.85%

M-H

2.620%

M

2.450%

M-L

2.120%

L

1.75%

1000200020202040

2060

2080

2100
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Carbon Emissions Baseline
4035

SRES High

Pessimistic
Optimistic

HM-H

Billions of tons

30

M
M-LH
M-H
L
M

25
20
15

M-L

pessimistic
technology
scenario
optimistic
technology
scenario

L

10
5
SRES Low

02000

2020

2040

2060

2080

2100
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Climate Sensitivity
10.8

CDF

0.6

0.4

0.2

00

12

34

56

78

Degrees CRR0104CG.10

Response Time for Alternative Climate Sensitivities
11.25°C
2.70°C

0.8
4.75°C

CDF

0.6

0.4

0.2

0050

100

150

200

Years
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Temperature Increase During 21st Century In theAbsence of Mitigation Policy
10.9
0.8
0.7
CDF

0.6
0.5
Optimistic
TechnologyPessimistic
Technology

0.4
0.3
0.2
0.1
002

2.7

3.1

46

Degrees C
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Issues
1. What is the range and likelihood of temperature change overthe 21st century in the absence of climate policy?
2. What is the impact of technological expectations on the least-costemission pathways for stabilizing global-mean temperature?
3. What is the impact of technological expectations on thenear-term price of carbon?
4. What is the potential value of a technology rich energy future?
5. Why focus on stabilizing temperature rather than concentrations?

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Percentage Reduction from the CO2 Emissions
Baseline (percent/year) for a 2°C Cap on
Temperature Change

Pessimistic Technology
Scenario

Optimistic Technology
Scenario

5th
50th
95th
5th
50th
95th
percentile percentile percentile percentile percentile percentile
2010

0

5200

3192020

1

9370

740

2030

119

5301960

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Issues
1. What is the range and likelihood of temperature change overthe 21st century in the absence of climate policy?
2. What is the impact of technological expectations on the least-costemission pathways for stabilizing global-mean temperature?
3. What is the impact of technological expectations on thenear-term price of carbon?
4. What is the potential value of a technology rich energy future?
5. Why focus on stabilizing temperature rather than concentrations?

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Price of Carbon ($/ton) with a 2°C Cap
on Temperature Change

Pessimistic Technology
Scenario

Optimistic Technology
Scenario

5th
50th
95th
5th
50th
95th
percentile percentile percentile percentile percentile percentile2010

236212022176

2020

462355037255

2030

6106637064409

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Temperature Increase During 21st Century In theAbsence of Mitigation Policy
10.9
0.8
0.7
CDF

0.6
0.5
Optimistic
Technology
Pessimistic
Technology

0.4
0.3
0.2
0.1
00123456Degrees C
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Carbon Price in 2010 with 2° and 3°C
Temperature Caps
10.9
3°C

0.8

2°C

0.7
CDF

0.60.5
Optimistic
Technology
Pessimistic
Technology

0.4
0.3
0.2
0.1
0050100150200

250

Dollars per ton of carbon
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Issues
1. What is the range and likelihood of temperature change overthe 21st century in the absence of climate policy?
2. What is the impact of technological expectations on the least-costemission pathways for stabilizing global-mean temperature?
3. What is the impact of technological expectations on thenear-term price of carbon?
4. What is the potential value of a technology rich energy future?
5. Why focus on stabilizing temperature rather than concentrations?

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Difference in Consumption Losses (in $ trillions) forTwo Technology Scenarios Under a 2°C Temperature
Cap – discounted to 2000 at 5%Consumption losses
under pessimistic
scenario
Consumption losses
under optimistic scenario
Difference inconsumption losses

5th
50th
95th
percentile percentile percentile
1.0
8.0
30.0

0.0

3.5

17.7

1.0

5.4

12.3

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Gross Benefits Under Alternative Temperature
Constraints
10.9
0.8
0.7
CDF

0.6
0.5

3°C
2°C

0.4
0.3
0.2
0.1
00

1.5

5.4

1020

Trillions of dollars – discounted to 2000 at 5%
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Issues
1. What is the range and likelihood of temperature change overthe 21st century in the absence of climate policy?
2. What is the impact of technological expectations on the least-costemission pathways for stabilizing global-mean temperature?
3. What is the impact of technological expectations on thenear-term price of carbon?
4. What is the potential value of a technology rich energy future?
5. Why focus on stabilizing temperature rather than concentrations?

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Stabilization of Atmospheric CO2 Concentrations(PPMV) for Alternative Temperature Caps

2°C
3°C

Pessimistic
Optimistic
Pessimistic
Optimistic

5th
percentile

50th
percentile

95th
percentile

417
414
535
523

472
445
574
580

743
503
669
592

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Causal Chain Between Human Activity
and Damages
Demographic/
Demographic/
Socio-economic/
Socio-economic/
Tech.
Tech.futures
futures

Emissions
EmissionsConcentrations
Concentrations

ClimateClimatechangechangeImpacts
Impacts
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