CLIMATE CHANGE 2014
Mitigation of Climate Change
Key Insights from the AR5

Co-Chair, IPCC Working GroupTokyo08 September 2014
Working Group III contribution to theIPCC Fifth Assessment Report© dreamstime

Prof. Dr. Ottmar Edenhofer

Exploring the solution space

CLIMATE CHANGE 2014
Mitigation of Climate Change

Working Group III contribution to theIPCC Fifth Assessment Report

IPCC reports are the result of extensive work of many scientists
from around the world.
1 Summary for Policymakers
1 Technical Summary
16 Chapters
235 Authors
900 Reviewers
More than 2000 pages
Close to 10,000 references
More than 38,000 comments
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Working Group III contribution to theIPCC Fifth Assessment Report

#1
What are the trends in stocks and flows of
GHG emissions?
Working Group III contribution to theIPCC Fifth Assessment Report

GHG emissions growth has accelerated
despite reduction efforts.

Working Group III contribution to the
IPCC Fifth Assessment Report

GHG emissions growth between 2000 and 2010 has been larger
than in the previous three decades.

±4.5Gt6

Working Group III contribution to theIPCC Fifth Assessment ReportAbout half of the cumulative anthropogenic CO2 emissions
between 1750 and 2010 have occurred in the last 40 years.

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Regional patterns of GHG emissions are shifting along withchanges in the world economy.

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Working Group III contribution to theIPCC Fifth Assessment ReportMost of the recent GHG emissions growth has been driven by
growth in economic activity.

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Working Group III contribution to theIPCC Fifth Assessment Report

The long-standing trend of gradual decarbonization of energy
has reversed recently.

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Working Group III contribution to theIPCC Fifth Assessment Report

#2
What does the WGIII AR5 tell us about
mitigation action required to limit
global warming to 2°C and 1.5°C?
Working Group III contribution to theIPCC Fifth Assessment ReportLimiting warming to 2°C relative to preindustrial levels involves substantial
technological, economic and institutionalchallenges.

Working Group III contribution to the
IPCC Fifth Assessment ReportWithout additional mitigation, global mean surface temperature
is projected to increase by 3.7 to 4.8°C (2.5 - 7.8°C) until 2100.

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Working Group III contribution to theIPCC Fifth Assessment ReportStabilization of atmospheric GHG concentrations requires
moving away from the baseline, regardless of the mitigation
goal.

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Working Group III contribution to theIPCC Fifth Assessment ReportStabilization of atmospheric GHG concentrations requires
moving away from the baseline, regardless of the mitigation
goal.

~3°15

Working Group III contribution to theIPCC Fifth Assessment ReportStabilization of atmospheric GHG concentrations requires
moving away from the baseline, regardless of the mitigation
goal.

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Working Group III contribution to theIPCC Fifth Assessment ReportMitigation involves substantial upscaling of low carbon energy.

17Working Group III contribution to theIPCC Fifth Assessment ReportDelaying mitigation increases the difficulty and narrows theoptions for limiting warming to 2°C.

„immediate action“

18Working Group III contribution to theIPCC Fifth Assessment ReportDelaying mitigation increases the difficulty and narrows theoptions for limiting warming to 2°C.

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Working Group III contribution to theIPCC Fifth Assessment ReportDelaying mitigation increases the difficulty and narrows theoptions for limiting warming to 2°C.

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Working Group III contribution to theIPCC Fifth Assessment ReportDelaying mitigation increases the difficulty and narrows theoptions for limiting warming to 2°C.

„delayed mitigation“„immediate action“

21Working Group III contribution to theIPCC Fifth Assessment ReportDelaying mitigation increases the difficulty and narrows theoptions for limiting warming to 2°C.

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Working Group III contribution to theIPCC Fifth Assessment ReportDelaying mitigation increases the difficulty and narrows theoptions for limiting warming to 2°C.

Current Cancun Pledges imply increased
mitigation challenges.

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Working Group III contribution to theIPCC Fifth Assessment ReportScientific evidence on the 1.5°C goal remains limited.
A comprehensive assessment is difficult in the absence of multimodel comparison studies and the limited number of studies
focusing on the 1.5°C goal. Existing studies indicate:• Temperature overshoot and large scale application of carbon
dioxide removal technologies• Immediate mitigation action• Rapid upscaling of the full set of technologies• Development along a low energy demand pathway
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Working Group III contribution to theIPCC Fifth Assessment ReportMitigation cost estimates vary, but global
GDP growth is not strongly affected.

Working Group III contribution to theIPCC Fifth Assessment ReportGlobal costs rise with the ambition of the mitigation goal.

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Working Group III contribution to theIPCC Fifth Assessment ReportLimited availability of technologies can greatly increasemitigation costs.

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Working Group III contribution to theIPCC Fifth Assessment Report

#3
What are the options for reducing GHG
emissions?
Working Group III contribution to theIPCC Fifth Assessment Report

Ambitious mitigation scenarios require afull decarbonization of energy supply.
Energy demand reductions can help toreduce emissions in the medium termand to hedge supply-side risks in thelong-run.

Working Group III contribution to theIPCC Fifth Assessment ReportMitigation scenarios show there is a lot of flexibility in how todecarbonize energy supply.

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Working Group III contribution to theIPCC Fifth Assessment Report

The scale of energy demand reductions determines the flexibility
in decarbonization options and the extent of supply-side risks,
infrastructure lock-in and co-benefits of mitigation.

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Working Group III contribution to theIPCC Fifth Assessment ReportSubstantial reductions in emissions would require substantialchanges in investment patterns.

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Working Group III contribution to theIPCC Fifth Assessment Report

#4What is the role of international
cooperation and national policies inreaching mitigation goals?
Working Group III contribution to theIPCC Fifth Assessment ReportClimate change mitigation is a global
commons problem that requires
international cooperation andcoordination across scales.

Working Group III contribution to theIPCC Fifth Assessment Report

There is far more carbon in the ground than emitted in any
baseline scenario.

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Working Group III contribution to theIPCC Fifth Assessment Report

The number of climate change policies at the national andinternational level is growing. So far, these policies have notinfluenced the emission trend significantly.

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Working Group III contribution to theIPCC Fifth Assessment Report

Examples of the performance of emission taxes
UK Climate Change Levy: 10% tax on electricity use• Electricity use reduction >22% at plants subject to the levy
compared to plants with voluntary agreement• No evidence of detrimental effect on the economy or migration ofindustry
Swedish carbon tax• Reductions in carbon intensity of GDP of 40%

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Working Group III contribution to theIPCC Fifth Assessment Report

Examples of the performance of emission taxes
Fuel taxes• In the long run 10%
higher fuel prices willlead to a roughly 7%
reduction in fuel use andemissions• OECD could havedecreased fuel use by
more than 35% if all
member countries had
chosen taxes as high as inthe UK
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Working Group III contribution to theIPCC Fifth Assessment Report

Regions are starting to cooperate.

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Working Group III contribution to theIPCC Fifth Assessment ReportInternational climate policy is only slowly taking shape.
• The UNFCCC regime is the only platform with broad legitimacy.
• Cooperation outside the UNFCCC has increased but except for
the Montreal Protocol did not lead to significant emissions
reduction.
• The Kyoto Protocol was less successful than envisaged.
• The emissions commitments were reached, benefitting from
economic changes in countries in transition.
• The market mechanisms have mobilized low-cost mitigation,
whose additionality is however debated.

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Working Group III contribution to theIPCC Fifth Assessment ReportMitigation can result in large co-benefits for human healthand other societal goals.

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Working Group III contribution to theIPCC Fifth Assessment ReportSome final thoughts beyond IPCC

• After all, carbon pricing is a good a idea: Taxing bads instead ofgoods.
• Finance ministers might be interested in carbon pricing even if
they doubt scientific evidence of climate change.
• Infrastructure investments can create short-term benefits.

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Working Group III contribution to theIPCC Fifth Assessment ReportCLIMATE CHANGE 2014www.mitigation2014.org
Working Group III contribution to theIPCC Fifth Assessment Report© dreamstime

Mitigation of Climate Change