ar5 highlights - working group iii

Working Group III contribution to the IPCC Fifth Assessment Report

© O

cean

/Cor

bis Youba SOKONA

Co-Chair, Working Group III

Highlights of the IPCC Fifth Assessment Report23 February 2015, Nairobi, Kenya


2

1 Summary for Policymakers

1 Technical Summary

16 Chapters

235 Authors

800+ Reviewers

Close to 1500 pages

Close to 10,000 references

More than 38,000 comments

IPCC reports are the result of extensive work of many scientists from around the world.


3

Climate change is a global commons problem that requires international cooperation and

coordination across scales.

© E

SA/N

ASA


4

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

Based on SRREN Figure 1.7


5

GHG emissions growth has accelerated despite reduction efforts.


6

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

Based on Figure 1.3


7

About half of the cumulative anthropogenic CO2 emissions between 1750 and 2010 have occurred in the last 40 years.

Based on Figure 5.3


8

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

Based on Figure 1.6


9

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

Based on Figure 1.6


10

GHG emissions rise with growth in GDP and population.

Based on Figure 1.7


11

The long-standing trend of decarbonization has reversed.

Based on Figure 1.7


Limiting warming involves substantial technological, economic and institutional challenges.


13

Based on WGII AR5 Figure 19.4

Without additional mitigation, global mean surface temperature is projected to increase by 3.7 to 4.8°C over the 21st century.


14

Stabilization of atmospheric GHG concentrations requires moving away from business as usual.

Based on Figure 6.7


15

Lower ambition mitigation goals require similar reductions of GHG emissions.

Based on Figure 6.9


16

Mitigation involves substantial upscaling of low-carbon energy.

Based on Figure 7.16


17

Mitigation involves substantial upscaling of low-carbon energy.



18

Many scenarios make it at least about as likely as not that warming will remain below 2°C relative to pre-industrial levels.

Based on Figures 6.32 and 7.16


19

Still, between 2030 and 2050, emissions would have to be reduced at an unprecedented rate...



20

...implying a rapid scale-up of low-carbon energy.



21

Delaying emissions reductions increases the difficulty and narrows the options for mitigation.



22




23




24

Mitigation cost estimates vary, but global GDP growth may not be strongly affected.


25

Global costs rise with the ambition of the mitigation goal.

Based on Table SPM.2


26

Mitigation can result in co-benefits for human health and other societal goals.



27

Climate change mitigation can result in co-benefits for human health and other societal goals.



28

• These influences can be substantial, although often difficult to quantify, and have not yet been thoroughly assessed in the literature.

• Co-benefits and adverse side-effects depend on local circumstances as well as on the implementation practice, pace and scale.

• Behaviour, lifestyle and culture have a considerable influence on emissions, with high mitigation potential in some sectors, in particular when complementing technological and structural change.

• Enhancing co-benefits and avoiding adverse side-effects: good governance, transparency, stakeholder participation, cross-sectoral analysis and design, etc.

Key points about co-benefits and adverse side effects


29

Low stabilization scenarios depend on a full decarbonization of energy supply.


30

Baseline scenarios suggest rising GHG emissions in all sectors, except for CO2 emissions from the land use sector.‐

Based on Figure TS.15


31

Mitigation requires changes throughout the economy. Systemic approaches are expected to be most effective.

Based on Figure TS.17


32

Effective mitigation will not be achieved if individual agents advance their own interests

independently.


33

• No single country can protect ‘its own’ climate by reducing its own emissions.

• Countries must persuade other countries to help it solve its climate problem.

• A country thus reduces its own emissions – and cooperates in other ways – for the sake of inducing reciprocal effort, i.e., getting other countries to do likewise.

• A country is more likely to be successful if it is perceived as doing its fair share of the effort.

• Thus, a cooperative agreement with equitable effort-sharing is more likely to be agreed and successfully implemented.

Climate change as a global commons problem: Equitable outcomes can lead to more effective cooperation.


34

Substantial reductions in emissions require significantchanges in investment patterns and appropriate policies.



Climate change mitigation is a necessary, but not a sufficient condition for sustainable development.

• Effort-sharing is fundamental to international cooperation in a global commons problem.

• There is a small set of broadly invoked ethical principles relating to equitable effort-sharing.

• Mitigation measures interact broadly (and sometimes strongly) with other sustainable development objectives, creating co-benefits or adverse side-effects.

• Highly context specific, difficult to quantify yet nonetheless significant both in welfare and political terms. Managing these interactions implies mainstreaming mitigation.


36

There has been a considerable increase in national and sub-national mitigation policies since AR4.



37

Sector-specific policies have been more widely used than economy-wide policies.



38

Climate change mitigation is a global commons problem that requires international cooperation across scales.


ar5 highlights - working group iii

Environment

assessment report mitigation

comments ipcc reports

srren figure

wgii ar5 figure

additional mitigation

carbon energy

world economy

substantial upscaling