The document summarizes key findings from the IPCC's Sixth Assessment Report Working Group III on mitigating climate change. It discusses how climate change scenarios inform the global energy transition, noting that immediate deep emissions reductions are needed to limit warming to 1.5°C. It outlines modeled mitigation strategies like transitioning from fossil fuels to renewables and efficiency improvements. Low demand scenarios that minimize energy demand through behavioral changes could offer large CO2 savings with lower costs and reliance on unproven technologies compared to traditional scenarios.

1. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
Low Demand Scenarios and the
IPCC 6th Assessment Report
(Working Group III)
David L. McCollum
ORNL (Oak Ridge National Laboratory)
IPCC AR6 (WG III TSU and Lead Author)
UNFCCC COP-27 (Sharm El Sheikh)
November 8, 2022
Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
[Matt Bridgestock, Director and Architect at John Gilbert Architects]

2. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
Climate Change Scenarios Inform and Guide the
Global Energy Systems Transformation
https://www.ipcc.ch/report/ar6/wg1/
https://www.ipcc.ch/report/ar6/wg2/
https://www.ipcc.ch/report/ar6/wg3/
Working Group I Working Group II Working Group III
• NDCs (Nationally Determined Contributions)
• Multi-national, national and sub-national energy,
environmental, and economic policies
• Corporate ESG targets
Science generates knowledge
and informs the possibility
space

3. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
“Unless there are immediate and deep emissions
reductions across all sectors, 1.5°C will be out of reach;
2.0°C would remain possible, but challenging.
The next years between now and 2030 are decisive.
Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
Findings from Chapter 3 and 4

4. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
Global temperatures will stabilize when the world reaches net zero
carbon dioxide emissions (‘balance between sources and sinks’)
NET ZERO CO2
EMISSIONS
EARLY 2050s 1.5°C
NET ZERO CO2
EMISSIONS
EARLY 2070s 2°C
(based on IPCC-assessed scenarios)
Credit: Volker Krey (IIASA)
NDCs
Current
Policies
2.8°C
3.2°C

5. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
“Modelled mitigation strategies to achieve these reductions
include transitioning from fossil fuels without CCS to very
low- or zero-carbon energy sources, such as
renewables or fossil fuels with CCS,
demand side measures and improving efficiency,
reducing non-CO2 emissions, and
deploying carbon dioxide removal (CDR) methods to
counterbalance residual GHG emissions. (high confidence)
Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
Findings from Summary for Policymakers

6. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
Modelling
teams
WGIII AR6 scenario
database
2266
scenarios
Initial
vetting
1686
scenarios
Vetting criteria:
Coherence with
historic trends
WG III scenario collection, vetting and assessment process
190 Models (91+ modeling families):
 98 globally comprehensive,
 71 national or multi-regional,
 20 sectoral models
Scenarios :
 3131 submitted scenarios (global, sectoral, national)
 2266 with sufficient information for climate assessment
 1686 scenarios passed the baseline vetting
 1202 in final Ch 3 climate assessment
Table SPM1
Climate
categorization
WGI Climate
emulators
(harmonization/infilling)
1202
scenarios
Credit: Ed Byers (IIASA)
The vast majority of 1.5 and 2.0 °C scenarios in the literature take a technology-centric approach, with heavy
reliance on supply-side solutions and the use of carbon dioxide removal.
Comparatively few explore demand-side measures and socio-cultural change in a concerted way.

7. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
“All mitigation strategies face implementation challenges, including technology
risks, scaling, and costs.
Many challenges, such as dependence on CDR, pressure on land and
biodiversity (e.g., bioenergy) and reliance on technologies with high upfront
investments (e.g., nuclear), are significantly reduced in modelled pathways that
assume using resources more efficiently (e.g., IMP-LD) or shift global
development towards sustainability (e.g., IMP-SP). (high confidence)
The impacts, risks and co-benefits of CDR deployment for ecosystems,
biodiversity and people will be highly variable depending on the method, site-
specific context, implementation and scale (high confidence).
Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
Findings from Summary for Policymakers
Note: ‘IMP-LD’ in AR6 is the same scenario as the ‘P1’ Illustrative Pathway in SR1.5.

8. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
Illustrative Mitigation Pathways (IMPs) =>
There are many ways to achieve net zero … with benefits and risks to each.
PRIMARY ENERGY
GHG EMISSIONS
Low Demand Sustainability
Renewables
Negative Emissions technologies
Credit: Keywan Riahi (IIASA)
Negative
Emissions
technologies

9. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
• The literature on low
demand scenarios is slowly
growing.
• Table 5.2 of Ch. 5
summarizes scenarios that
aim to:
• minimize service level energy
and resource demand as a
central mitigation tenet;
• evaluate the role of behavioral
change and Avoid-Shift-
Improve (ASI) strategies;
and/or
• achieve a carbon budget with
limited carbon dioxide removal
Table 5.2 contains additional rows that are not shown here.

10. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
Robust Insights Deriving from Low Demand Scenarios
1. Socio-cultural changes within transition pathways can offer Gigaton-scale CO2
savings potential at the global level, and therefore represent a substantial
overlooked strategy in traditional mitigation scenarios.
2. Deep demand reductions require parallel pursuit of behavioral change and
advanced energy efficient technology deployment; neither is sufficient on its
own.
3. Low demand scenarios can reduce both supply-side capacity additions and the
need for carbon capture and removal technologies to reach emissions targets.
4. The costs of reaching mitigation targets may be lower when incorporating Avoid-
Shift-Improve strategies for deep energy and resource demand reductions.
5. Achieving low demand requires combining innovations in several areas:
technological, behavioral, institutional, and business model
Sources: IPCC WG III AR6 Ch. 5, and Charlie Wilson (Oxford)

11. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
Characteristics of an Energy-Services Led
Transformation
• Inclusive wellbeing = decent living standards for all (well
above access and poverty thresholds)
• End-use transformations (efficiency, electrification) drive
upstream decarbonization
• Low resource use (energy, materials, land, water, …)
• Significant SDG synergies = remain within planetary
boundaries for climate, land-use, biodiversity, ...
• Key concept = services (i.e., amenities or functionalities like
thermal comfort, mobility, or nutrition that constitute wellbeing)
• focus on outputs and outcomes, instead of resource or economic inputs
• New Trends in Social and Technological Change
• Changing consumer preferences (e.g., diets)
• Generational change in materialism (access rather than ownership)
• New business models (sharing & circular economy)
• Pervasive digitalization and ICT convergence
• Rapid innovation in granular technologies
and integrated digital services
Source: Wilson, Grubler, and Zimm(2022). Energy-Services Led Transformation. In: Routledge Handbook of Energy Transitions(Ed: Araujo).
Grubler et al. (2018).

12. 12
AR6 WG III Scenario Database
(building on AR5 & SR1.5 experience)
Visit the Scenario Explorer at https://data.ece.iiasa.ac.at/ar6/
Special
Report
on
Global
Warming
of
1.5°C
(IPCC
SR15,
http://www.ipcc.ch/report/sr15/)
✔Facilitate collection of scenarios
from the community
✔Facilitates data sharing and
analysis during report writing
✔Establish internally consistent,
quality-controlled and comparable
datasets
✔Data security during report writing
✔Data transparency on publication
Credit: Ed Byers (IIASA)

13. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
SIXTH ASSESSMENT REPORT
Working Group III – Mitigation of Climate Change
Thank you!
David L. McCollum
ORNL (Oak Ridge National Laboratory)
IPCC AR6 (WG III TSU and Lead Author)
mccollumdl@ornl.gov

14. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
Appendix

15. Sixth Assessment Report
WORKING GROUP III – MITIGATION OF CLIMATE CHANGE
Source: Grubler et al. (2018).

16. quality
of life
urbanisation
new forms of
service
provision
user-oriented
(ICT) innovation
end-user
roles
granularity
decentralised
service
provision
rapid
transformation
accessing >
owning
digitalisation
of daily life
LED
scenario