Climate Change Science, Impacts, Mitigation

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Climate ChangeScience, Impacts, Mitigation
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Outline

• Understanding the climate system
• Anthropogenic influences on climate system
• Observed climate change
• Climate change modeling
• Reference emission scenarios
• Projected climate change
• Impacts of projected climate change
• Mitigation of GHG emissions and climate-change
  impacts

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Climate Average Weather

• Climate variables
• temp, precip, cloud type/amount, wind
• average over space, time mean, variability
• Climate system
• sun
• atmosphere gases, aerosols, clouds
• hydrosphere ocean, ice/snow, soil moisture
• biosphere transpiration, C/N/S cycles
• lithosphere weathering, volcanoes
• human impacts

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Components of the Climate System
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A One-Box Climate Model

• Climate system is like a closed box, with
  sunlight flowing in, and infrared energy flowing
  out

Heat, Q
Solar Energy, Fin
Infrared Energy, Fout

• Heat is the total kinetic energy of molecules in
  the system temperature is a measure of the
  average energy per molecule

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Reflected solar radiation
Outgoing infrared radiation
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Equilibrium Blackbody Temperature

• Constant stock of heat, constant global-mean
  temperatureis achieved when Fin Fout

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Blackbody v. Surface Temperature

• To is the temperature of the earth as seen from
  space temperature at top of the atmosphere
• To 255 K
• 255 273 18 C
• 1.8(-18) 32 0 F
• The actual global mean surface air temperature,
  Ts ? 290 K 17 C 63 F
• The difference (Ts To) 35 K 35 C 63 F
  is the greenhouse effect the fact that gases in
  the atmosphere absorb infrared radiation

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Climates of Other Planets
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Atmosphere is transparent to visible light, but
absorbs infrared
6000 K
255 K
temp increases until Fin Fout, area under
actual area under 255 K
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Absorption of infrared radiation by GHGs
electronic
rotational
vibrational
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Two-Box Model

• If atmosphere absorbs (and reradiates) fraction
  ? of infrared radiation

Atmosphere, Ta
Surface, Ts
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Annual/Global Mean Energy Balance
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Harte, III.6 Three-Box Model
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Radiative Forcing

• A change in the energy balance of the Earths
  climate system, calculated as follows
• change the concentration of a gas (e.g. CO2) or
  some other parameter (e.g., ?)
• calculate the instantaneous change in the energy
  budget of the Earth ?F Fin Fout
• all other climate parameters are held constant
• Over time, the climate system will adjust so that
  Fin Fout

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Temperature and Radiative Forcing
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?Ts from CO2 Doubling
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Climate Feedbacks

• Water Vapor
• increased evaporation
• Clouds
• increased clouds
• Ice and Snow
• decreased ice increased snow
• Oceans
• decreased dissolved CO2, decreased salinity
• Biosphere
• growth/decay, H2O, CO2, CH4, N2O cycling

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Water Vapor Feedback

Surface Temperature
Evaporation



Atmospheric Water Vapor
Increased IR absorption

Strong Positive Feedback
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Low Clouds High Clouds
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Cloud Feedback
High Uncertainty

Increased Albedo
Low Clouds




Surface Temperature
Evaporation



Increased IR absorption
High Clouds

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Ice-Albedo Feedbacks
Small positive or no feedback
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Global Thermohaline Circulation
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Ice-THC Feedbacks
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Biosphere Feedbacks

• Enhanced growth negative feedback
• higher CO2, rainfall, temp ? higher NPP ?
  increased carbon storage ? lower atm CO2
• Enhanced respiration/decay positive feedback
• warmer temperatures ? increased respiration,
  decay ? reduced carbon storage
• higher rainfall ? increased CH4 emissions
• Forest die-back and migration
• decreased carbon storage, decreased albedo,
  decrease transpiration

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Biospheric Feedbacks
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Feedback Summary
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Transient Response Mixed Layer

• Above, ?T is the equilibrium temperature change
  (surface global/annual average), ?Teq
• The temperature change as a function of time is
  given approximately

ocean mixed layer is about 100 m deep, 70 of
earth
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Concentrations non-constant flows

• c concentration of contaminant (mg/L, ?g/m3)

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Contamination and Clean-up
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Transient v. Equilibrium ?T
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Radiative Forcing of Climate Change
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CO2 Concentration air samples
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CO2 Concentration
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Carbon Emissions Fossil Fuel Cement
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Carbon Emissions Land Use Changes
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Carbon Emissions
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Methane Emissions
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Radiative Forcing Well-Mixed GHGs
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Equivalent CO2

• Total radiative forcing from all the well-mixed
  greenhouse gases is 2.43 W/m2
• The CO2 concentration that would produce an
  equivalent radiative forcing is given by

• CO2 concentration is 365 ppmv other GHGs are
  equivalent to an additional 73 ppmv of CO2
• When considering stabilization scenarios,
  important to take into account non-CO2 GHGs

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Global Warming Potential
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Predicted ?Ts from GHG ?F

• Calculated radiative forcing from observed
  increase in GHG concentration ?F 2.43 W/m2
• Predicted equilibrium change in global-mean
  surface temperature
• ?T2X 1.5 to 4.5 C gives ?T 1 to 3 C,
  compare to 0.6 C observed
• Missing transient response, other forcing

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Annual Aerosol Emissions (kg/km2h)
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Annual Aerosol Emissions (kg/km2h)
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Sulfate and carbon aerosol emissions
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Historical Sulfur Emissions
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Tropospheric Ozone Europe
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Solar Constant, 1979-99
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Solar Constant, 1600-2000
scaled to sunspot number based on Nimbus 7
Hoyt and Schatten
Lockwood Stamper
Lean et al.
Solanki Fligge
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Global/Annual Mean Radiative Forcing (1750-2000)
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Change in Radiative Forcing Anthropogenic
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Change in Radiative Forcing Natural
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Radiative Forcing 1979-95
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Observed Climate Change
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Estimates of Temperature Change
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Uncertainties 2 Standard Errors
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Temperature Trends by Period
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Temperature Trends by Season
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?T Greater at High Latitudes

• H2O is not well-mixed concentration, greenhouse
  effect much lower at high latitudes
• CO2 is well-mixed concentration, greenhouse
  effect is more uniform with latitude
• A given increase in CO2 therefore produces a
  larger relative change in forcing at high
  latitudes compared to low latitudes

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?T Greater during Winter

• H2O concentrations are higher during summer than
  winter
• CO2 concentrations are more uniform with season
  (but higher during winter than summer)
• A given increase in CO2 therefore produces a
  larger relative change in forcing during the
  winter compared to the summer

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?T Greater at Night

• The enhanced greenhouse effect due to increased
  CO2 (and other GHGs) operates day and night
• The effect of aerosolsnegative forcing due to
  increased reflection of sunlightoperates only
  during the day
• Thus, the temperature increase during night (due
  to GHGs) is greater than the temperature change
  during the day (due to GHG aerosols)
• Tmax Tmin diurnal temperature range

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Trends in Diurnal Temperature Range(1950-1993)
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Ocean heat-content changes, upper 300 m, 1948-1998
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Satellite v. surface temperature measurements
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Monthly (1966-00) and seasonal (1973-98) change
in snow cover in northern hemisphere, compared to
average of 25.2 Mkm2
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Trends in Freeze/Breakup Dates
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Monthly Arctic Sea-Ice Extent, 1973-96
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Seasonal Sea-Ice Extent, 1901-99
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Antarctic Sea-Ice Extent, 1973-96
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Glacier Length Records
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Paleoclimatology

• Instrumental records extend back to 1650, with
  decreasing geographical coverage other records
  (logs, diaries, letters) note major events
• Proxy data sources
• tree ring width, composition (1-8 ky BP)
• lake sediment width (5 ky BP)
• fossil pollen species (12 ky BP)
• positions of ice sheets, glaciers (25-40 ky BP)
• coral position, composition (100 ky BP)
• ocean sediments, fossil plankton (200 ky BP)
• air bubbles in ice cores (500 ky BP)

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Ice Cores
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Isotope Ratios

• Oxygen and hydrogen have more than one naturally
  occurring isotope
• H 1 (99.985), 2 (0.015)
• O 16 (99.762), 17 (0.038), 18 (0.20)
• At a given temperature, all molecules have the
  same average temperature, kinetic energy (½mv2
  kT) thus, lighter isotopes have velocities,
  evaporate faster
• O18O16 isotope ratio is measure of temperature
  when ice/snow was deposited

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Ocean Sediments
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NH Temperature Reconstruction
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Comparison of Reconstructions
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?T, CO2, CH4 Antarctic Ice Cores
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Temperature Variability over the last 400 ky
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Cause of Ice Ages Orbital Variations
Precession of equinox (23 ky)
Tilt of axis (40 ky)
Eccentricity (100 ky)
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Cause of Ice Ages Feedbacks

• Orbital variations can explain timing of observed
  climate changes over last 500 ky, but
• changes in solar forcing are only few W/m2, not
  sufficient to explain magnitude of climate change
• strong feedbacks must exist that amplify the
  solar forcinga reason for caution about our
  future?

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See Level 20 ky BP, during LGM, -120 m
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Temperature Variability over the last 25 ky
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Global Thermohaline Circulation
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THC and Rapid Climate Change
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Seasonal Precipitation Trends
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Precipitation Trends by Period
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El Niño-Southern Oscillation (ENSO)
Normal
El Niño
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El Niño-La Niña Variations, 1876-2000
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Increase in Mean Temperature
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Increase in Variance
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Increase in Mean and Variance
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Change in Number of Frost Days
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Change in Number of Frost Days
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Change in Heat Wave Duration
No. Consecutive days with Tmax gt 5 C above
1961-90 avg
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Change in Heat Wave Duration
Change in the number of consecutive days with
maximum temperature more than 5 C above 1961-90
average
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Change in Precipitation Intensity
Change in the maximum annual 5-day precipitation
total, over 1961-90 average
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Change in Precipitation Intensity
Change in proportion of annual precipitation
occurring on days on which the 95th percentile of
daily precipitation (over 1961-90) was exceeded.
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Number of US Hurricanes and Tornadoes
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Sea-level Rise 1700-2000
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Sea Level Last 140,000 y
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Components of Sea-level Rise
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Climate Change Modeling
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General Circulation Model (GCM)
The worlds fastest computers simulate 1 year of
climate in about 1 day
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Structure of the Atmosphere
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General Circulation
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Detection and attribution of climate
changemodeled v. observed ?T with and without
anthropogenic ?F
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Surface Temp Observed v. Model
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Observed v. Modeled Global Mean Temp
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Stratospheric Temp Observed v. Model
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Observed v. modeled precipitation trends ( per
century)
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Climate Sensitivity (?T2X) Summary
IPCC
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Outline

• Understanding the climate system
• Anthropogenic influences on climate system
• Observed climate change
• Climate change modeling
• Reference emission scenarios
• Projected climate change
• Impacts of projected climate change
• Mitigation of GHG emissions and climate-change
  impacts

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Reference Emission Scenarios
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Scenario Development
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Decomposing Fossil CO2 Emissions
Structure of energy supply
Per-capita Income
Emissions
Efficiency of energy use structure of economy
Population
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World Commercial Energy Use
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SRES Scenarios
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Average Growth Rates, 1990-2050
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SRES Scenarios
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Reference Emission Scenarios
pop econ inten low very
high high high low/med low low
high very high med medium medium
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CO2 Concentrations in SRES
4xCO2
3xCO2
2xCO2
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CO2 Scenarios
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Concentra-tions of other GHGs in SRES scenarios
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Aerosol Emissions in SRES Scenarios
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Projections of Future Climate Change
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?T observed v. modeled (IS92a)
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?P observed v. modeled (IS92a)
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?T for SRES A2 Scenario(2071-2100) (1961-1990)
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?T for SRES B2 Scenario(2071-2100) (1961-1990)
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Change in Runoff (in/yr)
lt-10 -10 to -6 -6 to -2 -2 to -1
-1 to 0 0 to 1 1 to 2 2
to 6 gt6
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?P () for SRES A2 Scenario(2071-2100)
(1961-1990)
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?P () for SRES B2 Scenario(2071-2100)
(1961-1990)
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?T for SRES Scenarios
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?T (v. 1990) for SRES Scenarios
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Models THC under IS92a
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Consistency of Modeled ?T by Region and Season
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Consistency of Modeled ?P by Region and Season
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Biospheric Feedbacks

• Illustration for one model and one (baseline)
  scenario, showing effects of modeled feedbacks on
  NPP, ?T, ?SL, and vegetation shift

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Impacts of Climate Change
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The Uncertainty Explosion
emission scenarios
carbon cycle response
range of possible impacts
global climate change
regional climate change
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Impacts

• Water
• water supply, irrigation, water pollution,
  hydropower, floods, navigation
• Ecosystems (and goods/services)
• agriculture, forests/forestry, wildlife, wetland,
  fisheries, coastal zones, biodiversity loss
• Human settlements
• sea-level rise and coastal infrastructure,
  floods, landslides, storms damage, energy use
• Human health
• heat/cold, air pollution, disease vectors

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Global water withdrawals and future projection,
without climate change
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Water Scarcity in Africa (no climate change)
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Change in Average Annual Runoff(2050, ensemble
mean)
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Per-capita water resources today and 2050 with
and without climate change
1990 2050, no climate change 2050, climate change
scenarios
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Impact of Climate Change on Water Withdrawals
Washington DC, 1990-2030

• Policy 1 no additional measures
• Policy 2 increased recycling, education,
  regulations
• Policy 3 50 real increase in water prices

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Scenarios of climate change impacts in 6 U.S.
basins, 2050
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Change in Annual Irrigation Requirements Due to
Climate Change2025 (1961-90)
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Percent Change in Cereal Production in 2060 from
CO2 doubling (?T2X 2.5-5 C)

• Adaptation (changes in crop and crop variety)
  significantly reduces impact of climate change
• Adaptive capacity of developing countries
  generally is much less than developed countries

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Impact on Agriculture of 2xCO2
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Impact on Agriculture of 2xCO2
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Change in Wheat Yield, 2050
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Changes in Crop Yields ()2xCO2, Various Climate
Models
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Trends in Net Grain Exports
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Ecosystem Migration

• Expected warming 1 to 3.5 C per century
• Migration of 150 to 550 km per century required
  to maintain similar climate conditions
• Historical rates for forests over last 100 ky
  0.4 to 5 km/century
• What is maximum?
• Dispersal rates of 100-200 km/century estimated
  for white pine (?1 C/century)

Die-back with release of C?
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Impact of 2xCO2 on ecosystem distribution
(Canadian model)
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Impact of 2xCO2 on ecosystem distribution (Hadley
model)
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Current, Future Forest Range 2xCO2
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Simulated Changes in Fish Habitat in Continental
US for 2xCO2
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Reef Bleaching

• Color in corals derives from microscopic algae
  (zooxantheallae) living in the coral (106/cm2)
• Widespread reports of bleaching (whitening) of
  corals, due to loss of zooxanthealle, have been
  reported over last 20 years
• May be due to increase in sea surface
  temperature, decrease in salinity, nutrient and
  sediment loadings, increased UV radiation

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Bleaching of Reefs, 1997-98
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Will Reefs Keep Up or Drown? Measured growth
rates fringing reefs 1-3 mm/y 10-30
cm/century barrier reefs 10-12 mm/y 100-120
cm/century Project sea-level rise 10-90
cm/century
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Causes of Sea Level Change
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Thermal Expansion IS92a
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IS92a Sea-level Rise v. Model
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Sea-level Rise v. SRES Scenarios
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Sea Level 90 cmOcean City, MD
Orleans, Cape Cod
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Long-term ?SL 2xCO2
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Long-term ?SL 4xCO2
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(No Transcript)
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Present Sea Level 5 m
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Human Settlements
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CAPACITY
Resources/Infrastructure/People
LOW
HIGH
URBAN
RURAL
medium
high/medium
medium/low
low
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medium
high/medium
medium/low
low
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Cost of Weather-Related Disasters
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Insured Weather-Related Losses, 1985-99
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Deaths, economic losses, and insurance losses
from natural disasters
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Temperature and Air Pollution
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Heat Stroke, Tokyo, 1980-95
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Disease Vectors
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Risk of Malaria
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fish
?SL
?P
?P
?P
?SL
?P
fish
?SL
?P
disease
ecosystems
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Asia
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Annual-average ?P, ?T in Asia
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WINTER (DJF)
SUMMER (JJA)
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Change in Monsoon Rainfall, 2xCO2
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Economics of Climate Change

• Traditional View
• Modern economies no sensitive to climate
• 3 GDP is very vulnerable (agriculture, forestry)
• 10 is somewhat vulnerable (construction, energy
  use, transportation, recreation)
• Impacts on developed countries are minor (1
  GDP), not enough to justify expensive mitigation
  (1 US GDP ? 100 G ? 70/tC)
• Impacts on developing countries greater, but they
  cant afford to pay greater returns to investing
  in economic development

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Economics of Climate Change

• Alternate View true impacts are much greater
  because traditional estimates ignore
• ecosystem/biodiversity loss, amenity
• risk of high-impact, unknown/unknowable events
• very long term impacts and discounting
• impact of climate variability on food supply

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Economic Losses Expert Opinion
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What is the Shape of the Cost Curve?
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Estimates of total economic losses ( GWP) due to
climate change, as a function of ?T
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Potential Climate Catastrophes

• Collapse of thermohaline circulation
• Collapse of West Antarctic Ice Shelf
• Release of methane clathrates (400 GtC in
  permafrost, 10,000 GtC in ocean)
• Massive forest die-back
• Major change in timing, intensity of monsoons
• Sudden, nonlinear change in climate sensitivity
• Unknown, unidentified, unimagined effects?

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Subjective Expert Opinion
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Time Scales of Climate Change
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Adaptation
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Build Dikes
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Adaptation to Climate Change
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Mitigation Greenhouse-Gas Emissions
Climate-Change Impacts
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Climate Change Chronology

• 1827 Fourier (France) describes greenhouse
  effect to explain small day-night temperature
  difference
• 1860 Tyndall (UK) measures ?F, attributes past
  climate change (ice ages) to variations in CO2
  concentration
• 1896 Arrhenius (Sweden) publishes theory of the
  enhanced greenhouse effect ?T2X 5-6 C
• 1938 Callendar (UK) first estimate of ?T,
  postulates this is due to increasing CO2
  concentrations from coal burning
• 1958 Revelle and Suess advocate, Keeling begins
  measuring CO2 concentration at Mauna Loa, Hawaii
• 1965 PCAST study on fossil fuels and climate
• 1970 MIT conference Mans Impact on Climate

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Climate Change Chronology

• 1975 NAS report estimates ?T2X 1.5 to 4.5 C
• 1979 First World Climate Conference
• 1980 Follow-up meetings in Villach, Bellagio
• 1982 Follow-up NAS report
• 1985 Advisory Group on Greenhouse Gases
• 1988 Hot summer, violent storms, icebergs
  Hanson
• Toronto 20 below by 2005, AOSOS
• IPCC formed by UNEP and WMO
• 1990 IPCC First Assessment 2nd World Climate
  Conf.
• 1992 UNFCC signed at UNCED, Rio de Janeiro
• 1994 UNFCC EIF

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The Ultimate Objective

• Stabilization of GHG concentrations at a level
  that would prevent dangerous anthropogenic
  interference with the climate system.
• Such a level should be achieved within a
  time-frame sufficient to allow ecosystems to
  adapt naturally, ensure that food production is
  not threatened and to enable economic development
  to proceed in a sustainable manner.
• Article 2, UNFCCC

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UNFCC, Article 3

• Parties should protect the climate systemon the
  basis of equity and in accordance with their
  common but differentiated responsibilities and
  respective capabilities. Accordingly, the
  developed country Parties should take the lead in
  combating climate change
• Parties should take precautionary measures Where
  there are threats of serious or irreversible
  damage, lack of full scientific certainty should
  not be used as a reason for postponing such
  measures
• Policies and measures should be cost-effective,
  cover all relevant sources, sinks and reservoirs
  of greenhouse gases and adaptation, and may be
  carried out cooperatively by Parties.
• All parties have a right to sustainable
  development.

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• Article 4. Commitments
• national inventories of sources and sinks (paid
  for by Annex II countries)
• formulate and publish mitigation plans (Annex I
  shall adopt and publish, for review at COP 1)
• promote technology transfer, promote sustainable
  development, conservation of sinks, etc.
• Article 5-6. Research, education, public
  awareness
• Article 7. Conference of the Parties (COP) every
  year to examine obligations in light of
  objective
• Article 8. Secretariat
• Article 9. Scientific and technological advice
• Articles 10-15. Implementation, financial
  mechanism, communication, amendments, annexes,
  protocols, voting, signature, ratification, entry
  into force, reservations, withdrawal

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Climate Change Chronology

• 1995 COP1, Berlin Mandate for QELROs by COP3
• 1996 IPCC SAR discernable human influence
• COP2, Geneva
• 1997 COP3, Kyoto Protocol signed
• 1998 COP4, Buenos Aires
• 1999 COP5, Bonn
• 2000 COP6, The Hague
• 2001 IPCC TAR Bush decision to unsign Kyoto
  Protocol
• COP7, Marrakesh
• 2002 COP8, New Delhi
• 2003 COP9, Milan

219
Kyoto Protocol

• Article 2. Annex I parties shall implement
  policies and measures to achieve quantified
  emission limitation and reduction commitments
• Article 3. A-I parties shall, individually or
  jointly, ensure that CO2-equiv. emissions of GHGs
  (CO2, CH4, N2O, HFC, PFC, SF6) do not exceed
  assigned amounts, with a view to reduce emissions
  by 5 below 1990 levels in 2008-12, using IPCC
  GWPs, and including sinks.
• Article 4. A-I parties may fulfill commitments
  jointly.
• Article 5. National systems of accounting.
• Article 6. Emission trading among Annex I
  parties, joint implementation, supplemental to
  domestic actions to meet commitments.

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Kyoto Protocol

• Articles 7-8. Submission, review of information.
• Articles 10-11. Non-annex I countries shall
  formulate plans to mitigate emission, paid for by
  Annex II
• Article 12. Clean development mechanism (CDM)
  Annex I can get ERU for investing in projects in
  non-Annex I countries leading to reductions in
  emissions that are additional to any that would
  occur in the absence of the certified project
  activity.
• Article 25. EIF 90 days after ratification by
  55 parties to FCCC, including parties accounting
  for 55 of 1990 Annex I emissions

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Climate Change Chronology

• 1995 COP1, Berlin Mandate for QELROs by COP3
• 1996 IPCC SAR discernable human influence
• COP2, Geneva
• 1997 COP3, Kyoto Protocol signed
• 1998 COP4, Buenos Aires
• 1999 COP5, Bonn
• 2000 COP6, The Hague
• 2001 IPCC TAR Bush decision to unsign Kyoto
  Protocol
• COP7, Marrakesh
• 2002 COP8, New Delhi
• 2003 COP9, Milan

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Compliance with Kyoto Projected Marginal Cost in
2010, /tC
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Compliance with Kyoto GDP Losses in Year 2010
224
GDP Loss Small Difference in Rates

• The effects of climate policy are often given in
  terms of the loss of GDP in a future year. Let
• F(t), F(t) GDP/y in year t without, with
  policy

Example, 1 loss of GDP in 10 years, r r
(0.01)/(10 y) 0.001 0.1/y in other words,
1.9 /y growth rate v. 2.0 /y growth rate
225
GDP Loss Large Difference in

• Let S(t), S(t) total GDP in years 0 through t
  without and with policy

r 0.020/y r 0.019/y Fo 1013/y
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Kyoto and Climate

• By itself, the Kyoto Protocol would have very
  little effect on climate change

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Emissions v. Concentration

• For gases with a simple residence time, such as
  CH4 (? ? 12 y) and N2O (? ? 120 y), stabilizing
  emissions stabilizes concentrations.

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CH4 and N2O
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Calculation for Methane
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Calculation for Nitrous Oxide
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Carbon Dioxide

• Unlike most other gases, CO2 does not have a
  fixed residence time.
• Because ?13 stays in atmosphere forever,
  stabilization ultimately requires zero emissions
• Constant CO2 emissions results in increasing CO2
  concentrations

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Stabilization Scenarios
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CO2 Emissions for Stabilization
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Long-term ?T for Stabilization
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Temperature change relative to 1990 (C) v.
stabilization level
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Choosing a Stabilization Level

• Costs are minimized (benefits maximized) when
• marginal cost marginal benefit
• costs of reducing the next unit of pollution
  benefits of the reduction

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Theory Can Be Hard to Put into Practice
238
Costs of Mitigation, 16 Models
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Threshold for THC Collapse
?T2X 3.7 C
1 /y 2 /y 1 /y 1 /y 0.5 /y
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Threshold for THC Collapse
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Stabilization Scenarios
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CO2 Emissions to Stabilization
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Problem Wont Solve Itself

• The era of cheap oil may end, but huge fossil
  resources remain that can be exploited at
  reasonable prices

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Scenarios in Perspective
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Reference v. Stabilization
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Fossil Reduction for 550 ppm
Total Fossil 2000
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Fossil Reduction for 450 ppm
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Achieving Fossil Reductions

• Increase price of fossil fuels (i.e., tax)
  reduce demand, stimulate alternatives
• 30-200/tC by 2050 to stabilize at 550 ppm
• 250-500/tC by 2050 to stabilize at 450 ppm
• For comparison
• existing energy taxes 30/tC
• polls 40/tC to address climate change
• 100/tC is equal to
• 12/bbl oil, 25/gal gasoline
• 75/ton coal, 2.5/kWh coal-fired electricity
• 0.5-1 trillion/yr in global tax revenue

249
Rates of Energy-Intensity, Carbon-Intensity
Change for Stabilization
250
A Typical Cost Curve
251
The Effect of Recycling on Net Cost
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Ancillary Benefits of Emission Reductionsair
pollution, materials damage, recreation,
vegetation, traffic noise/congestion, etc.
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Ancillary Benefit v. Carbon Tax
254
Cost Curves for Various Mitigation Options
255
Energy Efficiency Pulp and Paper
40
256
Energy Efficiency Petrochemicals
27
257
Energy Efficiency Ammonia Production
30
258
Energy Efficiency Iron and Steel
45
259
Energy Efficiency Cement Production
55
260
Passenger Car Fuel Economy 1980-95
261
Passenger Car Fuel Economy
262
Cost of Reducing Carbon Emissions
263
Cost of Stabilization
264
Cost of Stabilization (GWP)
265
Cost of Stabilization at 550 ppmv(discounted at
5/y)
266
Carbon Price for 550 ppm
267
Carbon Price for 450 ppm
268
Cost of Carbon-free Energy

• Most important factors are (1) cost of
  carbon-free energy, (2) demand scenario, (3)
  stabilization level
• If cost of carbon-free energy is about the same
  as fossil, small tax required regardless of
  demand or stabilization level
• If cost of carbon-free energy is much more than
  fossil, large tax required unless demand low and
  stabilization level high

269
Non-Fossil Reference Scenarios
270
Non-Fossil Stabilization at 550
without demand reductions
271
Non-Fossil Stabilization at 450
without demand reductions
272
Growth of Non-Fossil Energy
without demand reductions (i.e., carbon taxes)
273
300-1300 carbon-free EJ/y by 2050?(1 EJ/y 10
GWe 0.5 Prudhoe Bay)

• Not hydro
• 29 EJ/y in 2000 could double or triple
• Not geothermal
• 0.8 EJ/y in 2000 5-20 EJ/y hot water possible
• Not nuclear fusion
• Not tidal, wave, or ocean thermal
• 0.006 EJ/y in 2000 (tidal)
• thermal resource large, but low efficiency, large
  economic/technical challenges

274
Potential Major Sources

• Nuclear fission
• Biomass
• Solar
• Wind
• Decarbonized fossil fuels

275
Nuclear Fission

• Already deployed on large scale
• 437 reactors, 353 GWe
• 28 EJ/y, 16 world electricity production
• Near-term prospects dim
• significant growth unlikely for next 20 years
• near-term growth only in Asia (Japan, Korea,
  China, and India) possibly Russia
• significant decline possible in Europe, US

276
Installed Nuclear Capacity
277
Fraction of World Electricity Consumption
Generated by Nuclear (EIA)
278
Nuclear Fission

• To grow over the longer term, four issues must be
  addressed
• capital cost
• accident risk
• waste disposal
• proliferation
• Solutions must be appropriate for developing
  countries
• Electricity only

279
Nuclear Power in SRES Scenarios
280
Electrolytic H2 too expensive?
281
Capital Cost

• Nuclear twice as expensive as gas/coal in U.S.
• high capital cost, long construction times, high
  OM
• best nuclear plants are competitive with coal
• New ALWRs, standardized designs, streamlined
  regulation promise lower, predictable costs
• nuclear would be competitive with modest carbon
  tax
• New concepts small, modular plants produced
  largely in factories (like aircraft)

282
Safety

• Current reactors are safe if operated properly
• lt105 risk of core damage per reactor-year
• lt106 risk of a large release (gt1 fatality)
• lt108 risk of premature death for residents
• New ALWRs should be 10100 times safer should be
  safe enough even with ten-fold expansion
• Inherently safe reactors could virtually
  eliminate possibility of a large release

283
Westinghouse AP-600 an example of advanced,
passive safe reactor
284
Waste

• No country has operating repository for permanent
  disposal of high-level waste
• Cost, land use are not problems, but
• hard to prove no one, any time in future, could
  receive dose above standard
• assumes current (LNT-based) dose limits
• no detection, avoidance, removal, treatment
• Long-term international repositories
• Short-term dry-cask storage

285
Two dry casks can store fuel from operation of
1-GW reactor for one year
286
Proliferation

• All fuel cycles use nuclear explosive materials
  in fresh or spent fuel
• Once-through cycle is most economic, does not
  separate fissile materials
• If nuclear power grows substantially, U may
  become expensive, use of Pu will become
  economical
• each reactor produces 100 to 500 bombs-worth per
  year

287
Other Potential Major Sources
288
Biomass

• Mature technology, well-suited for developing
  countries
• Affordable portable fuels (liquids, H2)
• Aggressive use of wastes 30 EJ/y
• 1000 Mha energy crops 300 EJ/y
• 1000 Mha harvested for food
• 500-1000 Mha potentially arable (80 tropical)
• availability of land will depend on balance
  between growth in food consumption, yields

289
Wind

• 0.25 EJ/y in 2000, 20/y growth
• Mature technology, well-suited for developing
  countries (with a good grid)
• Electric only, intermittent
• Without storage, intercontinental transmission,
  practical limit roughly
• 100 EJ/y 40-100 Mha
• 10-20 world electricity in 2050

290
Solar

• 0.5 EJ/y in 2000 (mostly heat)
• High cost
• Low-temperature heat
• installed costs 400-2500/m2 10-100/GJ
• Electricity
• installed cost 5/Wp 0.2-0.5/kWh
• Intermittent source
• 10 world electricity in 2050 50-100 EJ/y
• 2-4 Mha sunny land

291
Decarbonized Fossil Fuels

• Recoverable resources are huge
• 105 EJ conventional, 106 EJ unconventional
• Huge existing industrial base
• Electricity or portable fuels,
• Cost, environmental impact of CO2 separation,
  transport, and disposal

292
Geoengineering

• Massive reforestation
• dump trees in ocean?
• Fertilize oceans?
• Pump CO2 in oceans, underground
• Particles in stratosphere, mirrors in orbit?