IPCC WG3 Symposium
September 8, 2014

Emission Pathways, Mitigation Costs
and the Economic Impacts

Keigo Akimoto
Research Institute of Innovative Technology for the Earth (RITE)(Guest Professor, the University of Tokyo)(LA of IPCC WGIII AR5, Chapter 6)

Long-term Emission Pathways

Baseline Emissions

3Figure 6.4- The median estimate of baseline CO2 emissions is around 80 GtCO2 in 2100, ofwhich is more than twice the current level, and smaller and larger than those in
RCP6.0 and RCP8.5, respectively. (RCP: Representative Concentration Pathway)- The emission of OECD1990 almost keeps the current level during the 21stcentury, but the emission of non-OECD1990 increases drastically.

Atmospheric GHG Concentration, Emission Reduction
in 2050, and Expected Temperature Increase(based on AR5 Table SPM.1, Table 6.3)

Probability of exceeding theGlobal GHG
Temperature temperature rise over 21stemissions in in 2100 (°C,century (relative to 18502050 (relative relative to1900)
1850-1900)
to 2010)
1.5 °C
2.0 °C
3.0 °C

Category byconcentrationin 2100 (ppmCO2eq)

Sub-categoryRCPs450 (430-480)―RCP2.6 -72−-41%1.5−1.7°C(1.0−2.8)

49-86%

12-37%

1-3%-57−-42%1.7−1.9°C(1.2−2.9)

80-87%

32-40%

3-4%-55−-25%

1.8−2.0°C(1.2−3.3)

88-96%

39-61%

4-10%-47−-19%2.0−2.2°C(1.4−3.6)

93-95%

54-70%

8-13%

95-99%

66-84%

8-19%

74-93%

14-35%

88-95%

26-43%

500 (480-530)

550 (530-580)(580-650)

No exceedanceof 530 ppm
CO2eq
Exceedance of
530 ppm CO2eq
No exceedanceof 580 ppm
CO2eq
Exceedance of580 ppm CO2eq-16−+7%―4-38−+24%
RCP4.5(650-720)―(720-1000)―

RCP6.0 +18−+54%

>1000

―

RCP8.5 +52−+95%-11−+17%

2.1−2.3°C(1.4−3.6)
2.3−2.6°C(1.5−4.2)
2.6−2.9°C(1.8−4.5)
3.1−3.7°C(2.1−5.8)
4.1−4.8°C(2.8−7.8)96100%
99100%
100100%100100%97100%
100100%55-83%
92-98%

Global Mean Temperature Changeof Different Scenario Categories

5Figure 6.13

Not only 430-480 ppm CO2eq, but also
480-530 ppm CO2eq scenarios also
expect 2 °C increase with the chancelarger than 50%.

As climate sensitivity has a large
uncertainty range, there is a considerable
chance to meet below +2 °C even under
530-580 ppm CO2eq scenarios.

Scenarios with Overshoot of Temperature
Figure 6.13?
?
??

- Scenarios with overshoot of atmospheric CO2 concentration and of temperature
were assessed in AR5 as well as concentration stabilization scenarios particularly
for tight temperature increase scenarios.
- High increase of actual global emissions after 2000 and “political” deep emission
reduction targets such as +2 °C target, combined together, induced to generatesuch overshoot scenarios to solve both two inconsistent conditions.

6

Emissions by Sector for 430-480 ppm- Negative emissions in electricity are required for 450 (430-530) ppm CO2eq scenarios
after 2050 by large use of BECCS.
- When CCS including BECCS is unavailable, large scale of afforestation is required.
- In both cases, the impacts on food prices through land conflict cause concern.

7

Global GHG Emissions in 2050
− Comparison with AR4 and AR5 −8Required emission reduction ratio in 2050
for below 2 °C relative to preindustrial level
Forth Assessment
Report (AR4)Fifth Assessment
Report (AR5)Fifth Assessment
Report (AR5)450 ppm CO2eq
stabilization
scenarios (best

Only the scenariosof 450 ppm CO2eq
in 2100

About 50% for
expecting below 2 °C
(including 500 ppm
CO2eq scenarios)

estimate of climatesensitivity)

Relative to
2000-50% to -85%

-26 to -65%

-6% to -65%

Relative to2010-60% to -88%

-41% to -72%

-25% to -72%

・According to the assessments of AR5, the required level of global GHG emission
reduction in 2050 for the 2 °C goal should be considered to be more flexible than theAR4 implication. For example, the levels are between -26% and -6% relative to 2000.
・They correspond to the level of -41 to -25% relative to 2010.

Lessons from the Long-term Scenarios of AR5

9♦ Global GHG emissions in baseline will continue to increaseduring this century, and the deep emission reductions aresurely required.
♦ A lot of emission scenarios (over 1000 scenarios) weregathered from several scientific communities in the world for
the AR5.
♦ According to the gathered scenarios, there are considerable
flexibilities in the long-term pathways to meet the 2°C goal,such as overshoots of atmospheric GHG concentration andof temperature change, probabilities below the target level tobe achieved (e.g., >50% or >66%).
♦ Consequently, the required global GHG emission reductions
by 2050 have wider ranges than those provided in the AR4.

Mitigation Costs and theEconomic Impacts

Marginal and Average Abatement Costs
430-530 ppm CO2eq
Around 100-300$/tCO2
Around 1000-3000$/tCO2- The global CO2 marginal abatement costs (Carbon prices) for 430-530 ppm CO2eq in
2050 and 2100 are about 100−300 $/tCO2 (25-75 percentile) and about 1000−3000 $/tCO2,respectively.
- It will be very challenging to achieve such deep levels of emission reductions. Carbon
pricing policies particularly explicit carbon pricing will not work for such high prices.

11Consumption and GDP Losses- GDP loss is about 4-10% (median: about 5%) of baseline GDP for 430-530 ppm in 2100.
- We should recognize that about 5% of GDP is not small by any means. The GDP ofAfrica in 2010 is about 2.4% of the global GDP. According to the outlook by RITE, theGDP of Africa in 2050 is still about 5% of the global GDP.

12

Cost Increase in the Scenarios with Limited
Availability of Technologies
Figure 6.24

- Some of the models estimated that it is impossible to achieve the GHG concentration at 450 ppm
CO2eq in 2100 when one of the key technologies are unavailable.
- The cost increase in the case without CCS is estimated to be about +29 to +297% (median: +138%)by a limited number of models which had the feasible solutions. The cost increases in the cases ofnuclear phase-out and limited solar/wind are about +7% and +6%, respectively (for the median).

13

For Sustainable Measures toward
Deep Emission Cuts
(Innovative Technologies Required)

RITE ALPS GHG Emission Scenarios
140
ALPS A-Baseline

120
GHG emission (GtCO2eq/yr)

ALPS A-CP6.0
100

ALPS A-CP4.5

80

ALPS A-CP3.7

60

ALPS A-CP3.0
RCP8.540
RCP6.020

RCP4.50
2150

2130

2110

2090

2070

2050

2030

2010

1990

RCP3PD(2.6)

Note: CO2 emissions including those from industrial processes and LULUCF
RCP: Representative Concentration Pathway
ALPS: ALternative Pathways toward Sustainable development and climate stabilization

15CO2 Marginal Abatement Costfor Different Stabilization Levels

Temperature change
relative to 1990

600
CO2 marginal abatement cost ($/tCO2)

16

ALPS A-CP6.0

3.3°C

ALPS A-CP4.5

2.8°C

ALPS A-CP3.7

2.3°C

ALPS A-CP3.0

1.9°C

500
400
300
200
IEA WEO2011
New Policy (EU)

1000
2000

IEA WEO2011
450 (US)
2020

2040

2060

2080

2100

Baseline:
4.1°C

Equilibrium Climate Sensitivity: 3.0 °C

High marginal abatement costs are estimated after 2040 particularly for the450 ppm CO2eq. (CP3.0) scenario, like the result of the AR5, even if all thecountries make the coordinated efforts (uniform marginal abatement cost) andthe least cost mitigation measures are adopted.

Image of Standard Scenarios for Deep Cuts

Carbonprice

17

Carbon price/
Marginal abatement cost

Baseline scenario
CO2emissionIntervention scenario

This situations cannot be expected in a real world. Particularly explicit
high carbon prices (e.g., over 100$/tCO2) in real price are unacceptable.

Possible Deep Cuts Scenario in a Real World
Carbonprice

CO2emission

18

Carbon price (inc. implicit carbon price)/Marginal abatement cost

BaselinescenarioAchieved by technologicaland social innovations

Intervention scenario

Mitigation measures avoiding high explicit carbon prices andtechnological and social innovations inducing low carbon prices are
key for deep emission cuts.

For Sustainable Measures from theViewpoint of Equitable Mitigation
Costs across Regions/Countries

Mitigation Costs across Countries♦ The mitigation costs summarized in the AR5 which wereshown in the previous slides were estimated underbasically the assumption of the least cost measures, thatmeans the equal marginal abatement costs acrosscountries were assumed.
♦ When the emission reduction measures with different
marginal abatement costs across countries areimplemented, the mitigation costs will be larger thanthose shown in AR5.
♦ Equitable efforts across countries will be required forachieving deep emission reductions with smaller
mitigation costs in the world.

20

Energy efficiency comparison
for major energy-intensive sectors
43

China

Coal power

US

39

India

37

Japan

35

Germany

33

South Africa

31

KoreaSource) RITE, 2014
based on IEA, 2013

Russia29

EU (27)27

Iron & steel
Oda et al. 2012;(BOF steel) Source)RITE, 2012

World25
1990

1995

2000

2005

2010

35

Primary energy consumption of BOF steel(GJ/ton of crude steel)

Efficiency (%)

41

21

2005
30
25.9 25.7

25

2010
28.3

23.1

22.9

26.8

34.5

33.1

27.7 27.7

28.1 28.2

FranceUK

28.9

28.3

29.1

30.0 30.3

33.2

31.1

28.3

23.5 23.8

20

15

10
Japan

Korea

Germany

China

India

BrazilUS

RussiaUkraineEmission Reduction Levels for Major Countries
in 2030 for Meeting the Least Cost (1/2)
MAC:
33 $/tCO2

200

22

MAC:
294 $/tCO2

GHG emissions (%)

150
100
500-50-100[relative to [relative to [relative to [relative to [relative to [relative to [relative to [relative to [relative to1990]
2005]
2010]
1990]
2005]
2010]
1990]
2005]
2010]
Baseline

United States

550ppmCO2eq

EU-27

Japan

Russia450ppmCO2eq

Korea

BrazilChina

Source: RITE DNE21+ for the EMF27 study

There are greatly different levels of emission reductions acrosscountries for the least cost mitigation measures.

India

Emission Reduction Levels for Major Countries
in 2030 for Meeting the Least Cost (2/2)

23100

550 ppm CO2eq
MAC: 33 $/tCO28040
200-20-40[relative to 1990][relative to 2005][relative to 2010]

550ppmCO2eq
United States

EU-27

Japan

Russia

Korea

BrazilChina

450 ppm CO2eq
MAC: 294 $/tCO2India
60
40
20

GHG emissions (%)

GHG emissions (%)

60

Source: RITE DNE21+ for the EMF27 study
Note: The assumption that nuclear power can be deployed andoperated also in Japan according to an international outlook fornuclear power are adopted.

0-20-40-60-80[relative to 1990][relative to 2005][relative to 2010]

450ppmCO2eq
United States

EU-27

Japan

Russia

Korea

BrazilChina

India

Conclusion

24♦ Climate change is a big issue and should be seriously tackled.
♦ IPCC AR5 greatly improved from the AR4 in several fields.

Assessments of emission pathways were also improved byseveral international collaboration projects etc.
♦ A certain range of emission levels and of emission pathways
exist even for meeting a certain target of temperature level, e.g.,
2 °C goal, with different probabilities of achievement,
overshoot/non-overshoot etc.
♦ Mitigation costs are large for deep emission reduction scenarios.
♦ Wide deployments of all the low-carbon technologies and thelarge contributions of all countries to emission reductions withequitable efforts will be necessary for deep emission reductions.
♦ In addition, innovative technologies will be required for deepemission reductions such as 450 ppm CO2eq. to be achieved in
the real world.

Appendix

Historical Global GHG Emissions Profiles
26

Despite several climate policies including Kyoto Protocol, the speed of global GHG
emission increase between 2000 and 2010 rather higher than that before 2000.

Historical CO2 Emissions for Country Income Groups
27

High Income Countries($12,616 and more)

Upper Middle Income Countries($4,086 to $12,615)(China, Brazil, Iran, Malaysia, South
Africa etc.)
Larger differences in emissions still exist inbetween HIC and UMC when consumptionbased measures are adopted.
Rapid increase in emissions in the Upper
Middle Income Countries

Lower Middle Income Countries($1,036 to $4,085)(India, Indonesia, Philippines, Egypt etc.)

Low Income Countries($1,035 and less)Relationship between CO2 Concentration Categoryand Probability Achieving the Temperature LevelFigure 6.14

Probabilityof 50%

Not only the atmospheric CO2 concentration level of 430-480 ppm CO2eq but
also of 480-530 ppm CO2eq will be able to expect to achieve the temperaturelevel below 2 °C with over 50% probability.

28

GHG Concentration and Temperature Changefor the RITE ALPS Scenarios

291100
ALPS A-Baseline
ALPS A-CP6.0
ALPS A-CP4.5

900

ALPS A-CP3.7800

ALPS A-CP3.0
RCP85700

RCP6600

RCP45500

RCP3PD

4007300
1990 2010 2030 2050 2070 2090 2110 2130 2150

ALPS A-Baseline

6Surface temperature
relative to pre-industrial (K)Concentratins incl. all forcing agents(CO2-eq.ppm)

1000

ALPS A-CP6.05

ALPS A-CP4.5
ALPS A-CP3.7

4

ALPS A-CP3.0
3

RCP8.5
RCP6.0

2RCP4.5
1Equilibrium Climate Sensitivity: 3.0 °C

RCP3PD01990 2010 2030 2050 2070 2090 2110 2130 2150