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SRES Scenario Emissions
Total Emissions (CO2 Equivalent)
160.0
140.0
120.0
100.0
80.0
Population, technology,
production, consumption
IS92a
A1T
A1FI
B2
B1
A2
A1B
Emissions
60.0
40.0
Atmospheric concentrations
20.0
0.0
1990
2010
2030
2050
2070
Cumulative CO2 Emissions
Working with Uncertainty
2090
Radiative forcing
Temperature rise and global
climate change
Temperature Increase
% Change in Cereal
Production
0
-2
0
1
2
3
4
-4
Direct impacts (e.g. crops,
forests, ecosystems)
-6
-8
-10
-12
Without Carbon Fertilisation
With Carbon Fertilisation
Socio-economic impacts
Probability
% Change in Global Cereal Production
Projected impacts of climate change
0°C
Food
Water
Global temperature change (relative to pre-industrial)
1°C
2°C
3°C
4°C
5°C
Falling crop yields in many areas, particularly
developing regions
Falling yields in many
Possible rising yields in
developed regions
some high latitude regions
Significant fall in water
Small mountain glaciers
availability e.g. Mediterranean
disappear – melt-water
and Southern Africa
supplies threatened in
several areas
Sea level rise
threatens major cities
Ecosystems
Extensive Damage
to Coral Reefs
Rising number of species face extinction
Extreme
Rising intensity of storms, forest fires, droughts, flooding, heat waves
Weather
Events
Risk of Abrupt and
Increasing risk of dangerous feedbacks and
Major Irreversible
abrupt, large-scale shifts in the climate system
Changes
Stabilisation and Commitment to Warming
5%
400 ppm CO2e
95%
450 ppm CO2e
550 ppm CO2e
650ppm CO2e
750ppm CO2e
Eventual temperature change (relative to pre-industrial)
0°C
1°C
2°C
3°C
4°C
5°C
4
‘Non-Market’
Market
Projection
Limit of coverage
of some studies,
including
Mendelsohn
Socially
contingent
None
Some studies,
e.g. Tol
Bounded
risks
None
System
change/
surprise
Limited to
Nordhaus and
Boyer/Hope
None
None
Models only have partial coverage of impacts
Values in the literature are a sub-total of impacts
Source: Watkiss, Downing et al. (2005)
Aggregate Impacts Matrix
• Essential to take
account of risk and
uncertainty
• Models do not provide
precise forecasts
• Assumptions on
discounting, risk
aversion and equity
affect the results
Market
impacts
Broad
impacts
Baseline
climate
5%
(0-12%)
11%
(2-27%)
High
climate
7%
(1-17%)
14%
(3-32%)
Rough estimate of equity
weighting: 20%
Sensitivity analysis: discounting
Value of £100 over time using different discount rates
£
100
90.5
90
80
70
60.6
60
50
0.1%
0.5%
40
1.0%
5.0%
2.0%
10.0%
36.6
30
20
13.3
10
0
0
10
20
30
40
50
60
70
80
90
0.6
0.0
100
Years
7
Economics of Stabilisation
450ppm CO2e
100
Global Emissions (GtCO2e)
90
80
500ppm CO2e (falling to
450ppm CO2e in 2150)
70
550ppm CO2e
60
Business as Usual
50
40
50GtCO2e
30
65GtCO2e
20
70GtCO2e
10
0
2000
2010
2020
2030
2040
2050
2060
2070
2080
2090
2100
Stabilising below 450ppm CO2e would require emissions to peak by
2010 with 6-10% p.a. decline thereafter.
If emissions peak in 2020, we can stabilise below 550ppm CO2e if we
achieve annual declines of 1 – 2.5% afterwards
Estimating Costs of Mitigation
Expected cost of cutting emissions consistent with
550ppm CO2e stabilisation trajectory averages 1% of
GDP per year.
•Macroeconomic models: 1% of GDP in 2050, in range +/- 3%.
•Resource cost: 1% of GDP in 2050, in range –1% to +3.5%.
Costs will not be evenly distributed:
•Competitiveness impacts can be reduced by acting together.
•New markets will be created. Investment in low-carbon electricity
sources could be worth over $500bn a year by 2050.
Strong mitigation is fully consistent with the aspirations
for growth and development in poor and rich countries.
9
Strategies for Emission Reduction
Four ways to cut
emissions:
• reducing demand
• improving efficiency
• lower-carbon technologies
• non-energy emissions
Illustrative Marginal Abatement Option
Cost Curve
Illustrative Distribution of Emission Savings
by Technology
Contributions to Carbon Abatement 2025
Efficiency
CCS
Nuclear
Biofuels
dCHP
Solar
Wind
Hydro
Contributions to Carbon Abatement, 2050
Abatement 11 GtCO2
Efficiency
CCS
Nuclear
Biofuels
dCHP
Solar
Wind
Hydro
Abatement 43 GtCO2
Average Cost of Reducing Fossil Fuel
Emissions to 18 GtCO2 in 2050
Cost of carbon abatement ($/tCO2)
150
$/tCO2
100
50
0
-50
2000
2010
2020
2030
2040
2050
-100
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Key principles of policy
Climate change policy:
– Carbon pricing
– R,D&D
– Related market failures and behavioural
change
Consistency with other policy goals –
growth and energy security
Conclusion from Stern analysis
• Our understanding of the risks of climate
change has advanced strongly.
• We understand the urgency and scale of
action required.
• We know that the technologies and
economic incentives for effective action
are available or can be created
• We are in a much better position now to use
our shared understanding to agree on
what goals to adopt and what action to take.