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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
SCIENCE
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
DAMAGES
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
‘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)
The PAGE model and other Integrated Assessment models
Percent of world GDP p
4
2
Global mean temperature
0
-2
0
1
2
3
-4
-6
-8
-10
-12
Hope
Mendelsohn
Nordhaus, output
Nordhaus, population
Tol, output
Tol, equity
4
5
6
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
10
STABILISATION
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
MITIGATION
COSTS
Strategies for Emission Reduction
Four ways to cut
emissions:
• reducing demand
• improving efficiency
• lower-carbon technologies
• non-energy emissions
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 $500bn a year by 2050.
Strong mitigation is fully consistent with the aspirations
for growth and development in poor and rich countries.
15
Illustrative Marginal Abatement Option
Cost Curve
The Relationship Between the Social Cost of
Carbon and Emissions Reductions
Social cost of
carbon
Marginal abatement
costs
2005
2050
Marginal abatement
costs rise
Innovation may
reduce average costs
Time
Emissions
reductions
Illustrative Distribution of Emission Savings
by Technology
Contributions to Carbon Abatement 2025
Efficiency
CCS
Nuclear
Biofuels
dCHP
Solar
Wind
Hydro
Contributions to Carbon Abatement, 2050
Abatement 11 GtCO2
Efficiency
CCS
Nuclear
Biofuels
dCHP
Solar
Wind
Hydro
Abatement 43 GtCO2
Average Cost of Reducing Fossil Fuel
Emissions to 18 GtCO2 in 2050
Cost of carbon abatement ($/tCO2)
150
$/tCO2
100
50
0
-50
2000
2010
2020
2030
2040
2050
-100
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POLICY
Mitigation policy instruments
• Pricing the externality- carbon pricing via tax
or trading, or implicitly through regulation
• Bringing forward lower carbon technologyresearch, development and deployment
• Overcoming information barriers and
transaction costs– regulation, standards
• Promoting a shared understanding of
responsible behaviour across all societies –
beyond sticks and carrots
Global carbon markets can be expanded
20000
18000
2 emissions, 2002
16000
Total em
issionsfromfossil fuels
E
m
issionsfrompow
erandindustrial sectors(estim
ated)
14000
12000
10000
MiliontonnesCO
8000
6000
4000
2000
0
E
uropeanU
nionU
nitedS
tatesof C
hina, India,
(25)
A
m
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M
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razil,
S
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(+5)
G
7
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25, Jap, A
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• Increasing the size of global carbon markets – by
expanding schemes to new sectors or countries, or
linking regional schemes – can drive large flows across
countries and promote action in developing countries
Adaptation
Adaptation is inevitable: climate change is with us and
more is on the way
Adaptation cannot be a substitute for mitigation
– only reduce the costs of climate change...
– ...but these are rising rapidly
– for severe impacts there are limits to what adaptation
can achieve
– Doesn't address risks and uncertainty
Adaptation crucial in developing countries
23
Conclusion from Stern analysis
Unless emissions are curbed, climate change will bring
high costs for human development, economies and the
environment
– Concentrations of 550ppm CO2e and above - very high risks of serious
economic impacts
– Concentrations of 450ppm CO2e and below - extremely difficult to achieve
now and with current and foreseeable technology
Limiting concentrations within this range is possible. The
costs are modest relative to the costs of inaction.
Decisive and strong international action is urgent: delay
means greater risks and higher costs
24
www.sternreview.org.uk
25