Ozone

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Stabilization Wedges Solving the Climate
Problem
BAU business as usual 1.5/yr avg growth
rate in CO2 emissions from the period 1975-2005
Present carbon emissions level 7
GtC/year Assertion we can solve the carbon
and climate problem in the next 50 years by
applying known technologies BAU reaches 14
GtC/yr. by 2050
Sci. Am. September 2006, p. 50 also see suppl.
material for Science 305, 968
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Stabilization Wedges Solving the Climate
Problem
BAU business as usual 1.5/yr avg growth
rate in CO2 emissions from the period 1975-2005
Present carbon emissions level 7 GtC/year A
wedge starts at zero and reaches 1 GtC/yr.
by 2056 Total additional carbon in the BAU is
175 GtC from 2006-2056 Each wedge removes a
total of 25 GtC by 2056 Seven wedges applied to
reach 1 GtC/yr saved each by 2056 175 GtC
why a wedge?
Sci. Am. September 2006, p. 50 also see suppl.
material for Science 305, 968
3
Stabilization Wedges Solving the Climate
Problem
BAU business as usual 1.5/yr avg growth
rate in CO2 emissions from the period 1975-2005
Of course, to achieve stabilization at any
level requires that ultimately the emissions
drop to zero This scenario if followed to
2056 would leave us at about 500 ppm
CO2 Scenario assumes 2 growth in energy con-
sumption/year Uncertainties population, C
sources/sinks
Sci. Am. September 2006, p. 50 also see suppl.
material for Science 305, 968
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15 wedges suggested

• General areas in
• which to achieve
• a wedge
• Energy efficiency
• Decarbonization of
• energy supply
• Shift fossil fuels
• CCS
• Alternative Energy
• Agriculture/Forestry

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Agriculture/Forestry Improving natural sinks
Two wedges achievable from Reducing tropical
deforestation Eliminate primary clearcutting
0.5 wedge Reforesting already-cut areas 0.5
wedge Establish new plantations on non-forested
land 0.5 wedge Improve crop tilling practices
carbon lost by increased aeration
comprehensive conservation tillage 0.5 1.0
wedge Issues preservation of biodiversity decre
ase likelihood of massive rainforest loss as T
increases need for land dedication to
agriculture verification and reversibility of
crop tillage practices
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Energy efficiency and conservation
Four wedges achievable from Increased auto fuel
economy (2 x 109 cars) 30 mpg average to 60 mpg
average 1 wedge reduce average mileage from
10K to 5K/year 1wedge Cut electricity use in
residential and commercial settings by 25 1
wedge Increase efficiency at coal-fired
electricity plants from 40 to 60 Plants of 1
GW capacity or larger, with 2x increase in coal
use Issues less tangible generally arise from
many small innovations design of urban areas and
mass transportation need for Government
incentives
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Decarbonizing Energy Supply
Nine wedges achievable from Switch from
coal-fired to gas-fired power generation 1
wedge Carbon emissions are roughly half at
natural gas plants Switch 4x as much coal to
gas, as there is gas presently used Implement
CCS (carbon capture and storage) 3
wedges Prevents 90 of carbon emissions, and
sequesters underground Install at conventional
coal or gas power plant 1 wedge Install at
H2-generation plants (H2 from coal, gas) 1
wedge Install at coal ? synfuels plants 1
wedge Alternative energies (replace coal
equivalent of energy) 3 wedges Add 2x current
capacity (700 GW) of nuclear fission 1
wedge Add 50x current capacity wind power (2
million at 1 MW) 1 wedge Add 700x current
capacity (2000 GW) solar power 1
wedge Alternative energies (replace gasoline
equivalent of energy) 2 wedges Add 100x
current capacity wind power to make H2 for cars
1 wedge Add 100x current US ethanol production
(1/6 world cropland) 1 wedge
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Growth in Energy Efficiency
Annual global growth rate in use of commercial
energy 2 Total energy/ year 400 x 1018 J
400 exajoules 1EJ 1018 J 100 EJ/year by
United States Over time in industrialized
countries the amount of energy consumed to
generate a unit of economic growth decreases
panel (a) Carbon intensity ratio of
CO2-equivalent emissions per unit of GDP
panel (b)
2003 US proposal in lieu of signing Kyoto accord
well reduce carbon intensity 18 by 2012! BUT
a 14 reduction would have been achieved without
doing anything new
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Expected future growth in energy consumption
much more in the developing countries Energy
efficiency in developed countries holds down
the growth of energy consumption
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Global primary energy use
1 W 1J/sec ? 14 TW (1 TW 1012 watts)
1 EJ 1018 J
(per year)

• 80 of energy from fossil fuels
• Three-quarters of Renewables are from
  developing countries biomass
• Solar wind together account for less than 1
• It is most likely that developing countries will
  switch from biomass to
• fossil fuels as economies develop

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