Transcript Mitigating Greenhouse Gas Emissions

Implications of alternative
metrics on mitigation costs and
agricultural GHG emissions
Andy Reisinger1 Petr Havlik2,3 Keywan Riahi2
Oscar van Vliet2 Michael Obersteiner2 Mario Herrero3
1 New
Zealand Agricultural Greenhouse Gas Research Centre
2 International Institute for Applied Systems Analysis (IIASA)
3 International Livestock Research Institute (ILRI)
Manuscript submitted to Climatic Change
Work funded by NZ Ministry of Agriculture and various EU-FP7 programs
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In a nutshell
100-year GWPs are not a cost-effective way of comparing GHGs
Alternative bio-physical metrics address some problems of GWPs –
but few studies have explored the cost and climate policy
implications if such metrics were to replace GWPs.
1. Determine the global cost-effectiveness of different
metrics under a variety of other assumptions
 100-year GTPs
 Time-dependent GTPs (focused on 2100)
 Exclusion of agricultural non-CO2 emissions
2. Evaluate regional implications of alternative metrics for
agricultural production and non-CO2 emissions
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Alternative metrics:
GWPs, fixed and time-dependent GTPs
CH4
N2O
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Emissions paths under alternative metrics
using MESSAGE
fixed 100-year GTPs: less CH4 mitigation
time-dependent GTPs: more CH4 mitigation
by 2100
Global agricultural marginal
abatement costs from Beach et al. (2008)
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Global
net costsresults
MESSAGE
450ppm
CH4 mitigation determines ‘atmospheric space’ for CO2 emissions
and hence total mitigation costs
550ppm
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Global agricultural CH4 emission pathways
5
rapid improvement in
agricultural mitigation
potential
no improvement in
agricultural mitigation
potential
rapid improvement in
agricultural mitigation
potential
250
200
150
NPV mitigation cost (US$ 2005 billion)
4000
100
50
3000
0
agriculture
CH4 2010 - 2050
2000
1000
0
Global discounted net
present value mitigation
costs (2010-2100)
Example for 550ppm
CO2-eq stabilisation
N2O 2010 - 2050
CH4 2050 - 2100
N2O 2050 - 2100
agriculture
industry
waste
forestry
energy
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GTP GTP
GWP CH
GTP GTP
GlobalGWPagricultural
emission pathways
(fixed) (time-dep.)
(fixed) 4
(time-dep.)
6
NPV mitigation cost (US$ 2005 billion)
5000
no improvement in
agricultural mitigation
potential
Global cost-effectiveness of metrics
• Fixed GTPs result in higher CO2 prices and higher total
mitigation costs than GWPs
• Time-dependent GTPs (focusing on year 2100) result in lower
CO2 prices and lower total mitigation costs than GWPs, but
escalating CH4 prices raise question about practical feasibility
• Assumptions about agriculture mitigation potential have a
larger effect on global costs than alternative metrics
• Different long-term stabilisation targets have a much larger
effect on global costs than alternative metrics
• Excluding agriculture globally is by far the most costly ‘metric’
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Regional implications
Use GLOBIOM to model agricultural production to 2050
• Spatially explicit partial equilibrium model for agriculture
and forestry (Havlik et al. 2010)
• Impose shadow prices for CO2, CH4 and N2O and biofuel
demands from global MESSAGE stabilisation runs under
alternative metrics:
 100-year GWPs (default)
 Fixed 100-year GTPs
 agricultural non-CO2 emissions excluded
• Explore regional agricultural production and GHG
emissions under additional GHG costs in all regions, and
effects on supply prices of livestock products
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Regional changes in livestock production
2030
Ruminant meat
Metrics have different effects regionally.
But the decision to impose a cost has a
bigger effect in most regions than the metric
by which the cost is imposed.
Some regions benefit from
a global mitigation response
because it increases their
competitive advantage.
Cattle milk
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Global agricultural CH4 emission pathways
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Regional changes in supply prices
Where future production increases
require land-use change, CO2 prices
dominate the response.
Otherwise, non-CO2 prices are
more important.
0.0
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Conclusions
GWPs are not the most cost-effective metric to compare GHGs
Fixed 100-year GTPs are even less cost-effective (+ 5 to 10%)
time-dependent GTPs would be more cost-effective (- 4 to 5%)
Cost implications of alternative metrics: smaller than
alternative assumptions about future agricultural mitigation
potential, and much smaller than choices of long-term target
Regional implications: depending on production systems and
land-use change, non-CO2 or CO2 prices have the dominant
effect on future production and supply prices
Further work: explore the implications for the political economy
of climate agreements, especially given their interaction with
supply prices and land-use change
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Impacts on global GDP
GWP - no improvement
GTP (fixed) - no improvement
GTP (time-dependent) - no improvement
GWP - rapid improvement
GTP (fixed) - rapid improvement
GTP (time-dependent) - rapid improvement
GDP loss in percent relative to baseline
8
6
450ppm CO 2-eq
Time-dependent GTPs defer
some mitigation costs
to future generations
4
550ppm CO2-eq
2
0
2020
2040
2060
Year
2080
2100
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Global GDP losses
12
Emissions paths under alternative metrics
using MESSAGE
Emissions paths for Leading
full set
of metrics and assumptions for agricultural abatement potential
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