Interim targets: Guideposts to reaching long-term climate change goals

Brian O’NeillInternational Institute for Applied Systems Analysis

Laxenburg, Austria

Contributors:James Wang & Bill Chameides, Environmental Defense

Michael Oppenheimer, Princeton UniversityAnnie Petsonk, Environmental DefenseIlkka Keppo & Keywan Riahi, IIASA

Presented at the IIASA-RITE International Symposium12 March 2007, Tokyo

Long-term Climate ChangePolicy Goals

1992: Framework ConventionObjective: “...stabilization of greenhouse gas concentrations 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. ….”

Short-term Climate ChangePolicy Goals

1997: Kyoto ProtocolLegally binding emissions reductions targets for industrialized countries for 2008-2012

2001: Many details of flexible mechanisms agreed to at COP 10 in Marrakech2005: Entry into force

Dangerous interference:Criteria for Concern, IPCC

Source: Smith et al., 2001, IPCC TAR WG2, Ch. 19.

ProblemWill be difficult (in the near future, impossible?) to agree on what level of climate change is “dangerous”Meanwhile,

we may commit ourselves to potentially dangerous levels of climate changewe may commit ourselves to potentially dangerous rates of climate changewe lack policy signals to guide decisions with long time horizons – exactly the kinds of decisions necessary for meeting long-term goals

Short-term policies (e.g., Kyoto Protocol) do not sufficiently guard against these problems

Proposal: Interim (Mid-Century) Concentration Targets

Based on O’Neill et al., 2005.

Proposal: Interim (Mid-Century) Concentration Targets

?

Based on O’Neill et al., 2005.

Proposal: Interim (Mid-Century) Concentration Targets

?

Based on O’Neill et al., 2005.

Proposal: Interim (Mid-Century) Concentration Targets

?

?

Based on O’Neill et al., 2005.

Interim Concentration Targets

Keep a range of century-scale targets feasible while uncertainties are narrowedLimit rates of climate change in the medium termBetter inform multi-decade planning horizonsMay broaden grounds for agreement in policy discussions Would require periodic review and updating as new information became availableDoes not imply any single policy regime for achieving it

Interim Concentration Targets

Targets could take range of forms, from weak to strong:

Evaluation framework for climate policy proposalsInformal aspirational goal(s)Formal targets under Convention/Protocol regime

Integrating point for parallel policy regimes?

Why Concentrations?

Balances uncertainty in consequences with uncertainty in required mitigation activity

Easier to detect progress toward concentration goal than temperature goalEquivalent CO2 integrates across multiple gases

activities -> emissions -> concentrations -> climate change -> impacts

Why Mid-Century?

Psychologically tractablePolitical precedents (GATT/WTO, Social Security)Long enough to affect rates of temperature change, short enough to constrain themConsistent with timescale of long-lived capital

Related Proposals or AnalysesMedium-term emissions goals by countries (e.g., UK) or states (e.g., California)

Global emissions goals (Corfee-Morlot and Hoehne, 2003; Pacala and Socolow, 2004)

Technology needs in medium term (Hoffert et al., 2002; Pershing and Tudela, 2003)

Recent policy proposals:WBCSD (Nov. 2006): mid-century global emissions goal

GROCC (Feb. 2007): “ambitious but achievable” mid-century CO2 concentration target

Constraining Rates of Change

Rate of Temperature ChangeDifferent pathways to same long-term stabilization level imply substantially different rates of warming in the interim periodDifferences in rates of warming are large enough to be of concern for impacts that might be considered “dangerous”Examples: Thermohaline circulation shutdown, ecosystem impacts.

Source: O’Neill and Oppenheimer, PNAS, 2004.

Illustrative Emissions Pathways

Peak then declinepathway for Kyoto gases

Non-Kyoto gasesfollow medianof SRES scenarios

A range of concentrationtargets achievedin 2050

Constant annual % declinePeak then decline

Source: Wang et al., in prep.

Rate of Change vs. 2050 Target

Source:

Wang et al.

0

0.1

0.2

0.3

0.4

Median

SRES

2.0

3.0

4.5

Climatesensitivity

Tem

pera

ture

Cha

nge

2000

-205

0

(deg

C/d

ecad

e)

550 600400 450 500

Eqv. CO2, Kyoto gases only, 2050 (ppm)

Rate of Change vs. 2050 Target

Eqv. CO2, Kyoto gases only, 2050 (ppm)400 450 500 550 600

0

0.1

0.2

0.3

0.4

Range =

430 – 520 ppm

2.0

3.0

4.5

Climatesensitivity

Median

SRES

Tem

pera

ture

Cha

nge

2000

-205

0

(deg

C/d

ecad

e)

Source:

Wang et al.

Keeping Long-Term Options Open:

Exploring Atmospheric Pathways

Interim Targets and Long-TermTemperature Change

400 450 500 550 6000

1.0

2.0

3.0

4.0

Post

-205

0 em

issi

on d

eclin

e (%

/yr)

Global AverageTemperatureChange, 2200s

Median

SRES

Eqv. CO2, Kyoto gases only, 2050 (ppm) Source:

Wang et al.

Interim Targets and Long-TermTemperature Change

400 450 500 550 6000

1.0

2.0

3.0

4.0

Post

-205

0 em

issi

on d

eclin

e (%

/yr)

Median

SRES

Eqv. CO2, Kyoto gases only, 2050 (ppm) Source:

Wang et al.

Interim Targets and Long-TermTemperature Change

400 450 500 550 6000

1.0

2.0

3.0

4.0

Median

SRES

Post

-205

0 em

issi

on d

eclin

e (%

/yr)

Eqv. CO2, Kyoto gases only, 2050 (ppm) Source:

Wang et al.

Interim Targets and Long-TermTemperature Change

400 450 500 550 6000

1.0

2.0

3.0

4.0

Post

-205

0 em

issi

on d

eclin

e (%

/yr)

Median

SRES

Eqv. CO2, Kyoto gases only, 2050 (ppm) Source:

Wang et al.

Interim Targets and Long-TermTemperature Change

Source:

Wang et al.

Eqv. CO2, Kyoto gases only, 2050 (ppm)400 450 500 550 600

1.0

2.0

3.0

4.0

Post

-205

0 em

issi

on d

eclin

e (%

/yr)

Median

SRES

Upper

Bound

Lower

bound

0

Interim Targets and Long-TermTemperature Change

Source:

Wang et al.

Eqv. CO2, Kyoto gases only, 2050 (ppm)400 450 500 550 600

1.0

2.0

3.0

4.0

Post

-205

0 em

issi

on d

eclin

e (%

/yr)

Median

SRES

Upper

Bound

Lower

bound

0

Interim Targets and Long-TermTemperature Change

400 450 500 550 6000

1.0

2.0

3.0

4.0

Post

-205

0 em

issi

on d

eclin

e (%

/yr)

Median

SRES

Eqv. CO2, Kyoto gases only, 2050 (ppm) Source:

Wang et al.

Interim Targets and Long-TermTemperature Change

400 450 500 550 6000

1.0

2.0

3.0

4.0

Post

-205

0 em

issi

on d

eclin

e (%

/yr)

Median

SRES

Eqv. CO2, Kyoto gases only, 2050 (ppm) Source:

Wang et al.

Keeping Long-Term Options Open:

What Kind of Target?

Medium-term Conditions in GGI Mitigation Scenarios

IIASA Integrated Assessment Framework

Medium-term Conditions in GGI Mitigation Scenarios

0

200

400

600

800

1000

1200

1400

1600

1800

2000 2020 2040 2060 2080 2100 2120

CO

2eq

conc

entra

tion,

ppm

B1 B1-670 B1-590 B1-520B1-480 A2r A2r-1390 A2r-1090A2r-970 A2r-820 A2r-670

A2

B1

(b)

Source: Keppo et al., TFSC, 2007.

Medium-term Conditions in GGI Mitigation Scenarios

0%

20%

40%

60%

80%

100%

440 460 480 500 520 540 560 580 600 620 640 660 680

CO2 eqivalent concentration (2050)

Prob

abili

ty o

f sta

ying

bel

ow th

e ta

rget

2°C

3°C

A2rB1r

Source: Keppo et al., TFSC, 2007.

Medium-term Conditions in GGI Mitigation Scenarios

0%

20%

40%

60%

80%

100%

400 420 440 460 480 500 520 540 560 580

CO2 concentration (2050)

Prob

abili

ty o

f sta

ying

bel

ow th

e ta

rget

2°C

3°C

A2rB1r

Source: Keppo et al., TFSC, 2007.

Medium-term Conditions in GGI Mitigation Scenarios

0%

20%

40%

60%

80%

100%

0% 20% 40% 60% 80% 100%

Share of zero-carbon energy (2050)

Prob

abili

ty o

f sta

ying

bel

ow th

e ta

rget

2°C

3°C

2000

A2r B1r

Source: Keppo et al., TFSC, 2007.

ConclusionsAn interim target could constrain rates of temperature change and preserve long-term options, serving as a bridge to a longer term climate goalTarget setting plus regular review could serve as important anchor for medium-term policy expectations, facilitating long-term investmentsA globally-agreed interim target could serve as means of integrating across a fragmented international policy regimeUseful additional analysis:

Implications of different metrics for an interim target: what medium-term conditions would position us best for the second half of the century?Costs and political feasibility of different interim targetsImplications of interim targets for shorter-term actions

Mitigation Costs of Interim Targets:

Research Needs

Costs in GGI Mitigation Scenarios

0

0.2

0.4

0.6

0.8

1

0.0% 0.5% 1.0% 1.5% 2.0% 2.5% 3.0%

GDP losses

Prob

abili

ty o

f ach

ievi

ng g

oal

B1, 2 degrees B1, 3 degreesA2, 2 degrees A2, 3 degrees

B1, 3 deg

B1, 2 deg

A2, 3 deg

A2, 2 deg

Source: Calculated based on Keppo et al., TFSC, 2007.

Costs in GGI Mitigation Scenarios

0

0.2

0.4

0.6

0.8

1

0.0% 0.5% 1.0% 1.5% 2.0% 2.5% 3.0%

GDP losses

Prob

abili

ty o

f ach

ievi

ng g

oal

B1, 2 degrees B1, 3 degreesA2, 2 degrees A2, 3 degrees

B1, 3 deg

B1, 2 deg

A2, 3 deg

A2, 2 deg

70% likelihood

Source: Calculated based on Keppo et al., TFSC, 2007.

Costs in GGI Mitigation Scenarios

0

0.2

0.4

0.6

0.8

1

0.0% 0.5% 1.0% 1.5% 2.0% 2.5% 3.0%

GDP losses

Prob

abili

ty o

f ach

ievi

ng g

oal

B1, 2 degrees B1, 3 degreesA2, 2 degrees A2, 3 degrees

B1, 3 deg

B1, 2 deg

A2, 3 deg

A2, 2 deg

70% likelihood

Source: Calculated based on Keppo et al., TFSC, 2007.

Costs of Interim Targets70 % confidence required for reaching the target

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

430 440 450 460 470 480 490 500 510

CO2 concentration in 2050

GDP

loss

es, %

B1, 2 degrees B1, 3 degrees A2, 3 degrees

A2, 3 deg

B1, 2 deg

B1, 3 deg

Source: Calculated based on Keppo et al., TFSC, 2007.

Costs of Interim Targets70 % confidence required for reaching the target

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

430 440 450 460 470 480 490 500 510

CO2 concentration in 2050

GD

P lo

sses

, %

B1, 2 degrees B1, 3 degrees A2, 3 degrees

A2, 3 deg

B1, 2 deg

B1, 3 deg

HypotheticalInterimTarget

How do costs change?What new information willbe available in 2050?

?

Source: Calculated based on Keppo et al., TFSC, 2007.