Alan Robock

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Warming TrendsAre Here to StayClimate Change
and How it Affects Us
Alan Robock Department of Environmental
Sciences Rutgers University, New Brunswick, New
Jersey USA
robock_at_envsci.rutgers.edu
http//envsci.rutgers.edu/robock
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http//data.giss.nasa.gov/gistemp/graphs/Fig.A2.pd
f
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Paleoclimate information supports the
interpretation that the warmth of the last half
century is unusual in at least the previous 1300
years. The last time the polar regions were
significantly warmer than present for an extended
period (about 125,000 years ago), reductions in
polar ice volume led to 4 to 6 metres of sea
level rise.
Mann et al. (1999)
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Global Warming Fundamental Questions
1. How will climate change in the future? 2. How
will climate change affect us? 3. What should we
do about it?
Considerable warming, glacier retreat, more
precipitation and extremes, extinctions, stronger
hurricanes, and sea level rise Some winners but
more losers, including water, tropical
agriculture, national security Mitigation now
(reduce emissions, efficiency) is cheaper than
waiting, study impacts, adapt
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Global Warming Fundamental Questions
1. How will climate change in the future? 2.
How will climate change affect us? 3. What
should we do about it?
Intergovernmental Panel on Climate Change (IPCC)
Working Group I (WG I) IPCC WG II IPCC WG III
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Intergovernmental Panel on Climate Change
(IPCC) Established in 1988 jointly by the World
Meteorological Organization and the UN
Environment Programme 3000 scientists from more
than 150 nations
First Assessment Report (FAR), 1990 Second
Assessment Report (SAR), 1996 Third Assessment
Report (TAR), 2001 Fourth Assessment Report
(4AR), 2007
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In this Summary for Policymakers, the following
terms have been used to indicate the assessed
likelihood, using expert judgment, of an outcome
or a result Virtually certain gt 99
probability of occurrence Extremely likely gt
95 Very likely gt 90 Likely gt 66 More likely
than not gt 50 Unlikely lt 33, Very unlikely lt
10 Extremely unlikely lt 5
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The unequivocal detection of the enhanced
greenhouse effectfrom observations is not likely
for a decade or more. Climate Change The IPCC
Scientific Assessment (1990)
The balance of evidence suggests a discernible
human influence on global climate. Climate
Change 1995 The Second Assessment of the
Intergovernmental Panel on Climate Change (IPCC)
Most of the observed warming over the last 50
years is likely to have been due to the increase
in greenhouse gas concentrations. Climate Change
2000 The Third Assessment Report of the IPCC
Most of the observed increase in globally
averaged temperaturessince the mid-20th century
is very likely due to theobserved increase in
anthropogenic greenhouse gas concentrations. Clim
ate Change 2007 The Fourth Assessment Report of
the IPCC
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The unequivocal detection of the enhanced
greenhouse effectfrom observations is not likely
for a decade or more. Climate Change The IPCC
Scientific Assessment (1990)
The balance of evidence suggests a discernible
human influence on global climate. Climate
Change 1995 The Second Assessment of the
Intergovernmental Panel on Climate Change (IPCC)
Most of the observed warming over the last 50
years is likely to have been due to the increase
in greenhouse gas concentrations. Climate Change
2000 The Third Assessment Report of the IPCC
Most of the observed increase in globally
averaged temperaturessince the mid-20th century
is very likely due to theobserved increase in
anthropogenic greenhouse gas concentrations. Clim
ate Change 2007 The Fourth Assessment Report of
the IPCC
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Warming of the climate system is unequivocal, as
is now evident from observations of increases
in global average air and ocean temperatures,
widespread melting of snow and ice, and rising
global mean sea level. Discernible human
influences now extend to other aspects of
climate, including ocean warming,
continental-average temperatures, temperature
extremes and wind patterns. Climate Change
2007 The Fourth Assessment Report of the IPCC,
Working Group I
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Greenhouse gases are now higher than any time in
the past 650,000 years.
Brook, E., 2005 Tiny bubbles tell all, Science,
310, 1285-1287.
Time
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Elevated Eocene Atmospheric CO2 and Its
Subsequent Decline Tim K. Lowenstein and Robert
V. Demicco
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The equilibrium climate sensitivity is a
measure of the climate system response to
sustained radiative forcing. It is not a
projection but is defined as the global average
surface warming following a doubling of carbon
dioxide concentrations. It is likely to be in the
range 2 to 4.5C with a best estimate of about
3C, and is very unlikely to be less than 1.5C.
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IPCC AR4 Simulations with all forcings,including
humans (from 13 different climate models from
around the world) with only natural forcings
observations
models
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Fundamental Determinants of Climate
1. Input of solar radiation 2. Atmospheric
composition (gases and aerosols) 3. Surface
characteristics (albedo, roughness, potential
evapotranspiration)
Humans can change climate by affecting 2 or 3.
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Earths global, annual mean energy balance
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Earths global, annual mean energy balance
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Greenhouse Effect
A 4p r2
A p r2
Sun
Ts
Earth
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Global Energy Balance Incoming Energy
Outgoing Energy pr2 S0 (1-a) 4pr2 sTe4
r radius of Earth S0 solar constant
(1368 W/m2) a planetary albedo
(0.30) s Stefan-Boltzmann constant (5.67 x
108 W m-2 K-4) Te effective temperature of the
Earth Ts observed global average surface
temperature Greenhouse Effect Ts 288
K Te 255 K 33 K (33C 59F)
Greenhouse Effect
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Earths global, annual mean energy balance
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NCAR PCM climate model
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Observations
As simulated with all forcings
As simulated with only natural forcings
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Better tools for projection The new
assessment of the likely ranges now relies on a
larger number of climate models of increasing
complexity and realism, as well as new
information regarding the nature of feedbacks
from the carbon cycle and constraints on climate
response from observations. Warming tends to
reduce land and ocean uptake of atmospheric
carbon dioxide, increasing the fraction
of anthropogenic emissions that remains in the
atmosphere.
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NASA GISS climate model
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CCSM Climate Forecasts
(C)
(C)
Produced by Gary Strand, NCAR
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A1FI
A1B
A1T
B1
A2
B2
CO2 emissions
CH4 emissions
SO2 emissions
CO2 concentrations
CH4 concentrations
N2O concentrations
Radiative forcing
Global mean temperature
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For the next two decades a warming of about
0.2C per decade is projected for a range of SRES
emission scenarios.
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For the next two decades a warming of about
0.2C per decade is projected for a range of SRES
emission scenarios. Even if the concentrations
of all greenhouse gases and aerosols had been
kept constant at year 2000 levels, a further
warming of about 0.1C per decade would be
expected.
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Increases in the amount of precipitation are
very likely in high-latitudes, while decreases
are likely in most subtropical land regions,
continuing observed patterns in recent trends.
Relative changes in precipitation () for the
period 20902099, relative to 19801999.
Stippled areas are where more than 90 of the
models agree in the sign of the change.
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Based on a range of models, it is likely that
future tropical cyclones (typhoons and
hurricanes) will become more intense, with larger
peak wind speeds and more heavy precipitation
associated with ongoing increases of tropical
SSTs.
Hurricane Katrina, August 29, 2005, 1445
GMT(1045 am, EDT)
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Annual average number of tropical cyclones (winds
gt39 mph)About 80 of the tropical stormswill
grow into 75 mph hurricanes or typhoons.
Source The USA TODAY Weather Book by Jack
Williams
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Hurricane Katrina, August 29, 2005, 1445 GMT
(1045 am, EDT)
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Hurricane Rita, September 23, 2005, 2015 GMT
(415 pm, EDT)
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Hurricane Wilma, October 19, 2005The most
intense hurricane on record in the Atlantic,with
central pressure of 882 mb and winds of 175 mph.
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Why would a warmer climate produce stronger
hurricanes? 1. A warmer ocean surface provides
more evaporation of water vapor, the fuel for
hurricanes. 2. The middle troposphere will warm
more than the surface, which would tend to
inhibit hurricanes, but the enhanced evaporation
effect is stronger. Climate model results tell
us 1. Hurricanes will be stronger in a warmer
climate. There will be more strong
hurricanes. 2. No evidence for more hurricanes
where they already occur, but tracks will move
poleward. 3. Hurricanes will start to appear in
the South Atlantic, which is currently too cold
to support hurricanes.
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where Vmax is the maximum sustained wind speed
measured at the standard height of 10 m.
The PDI is the power dissipation index, a measure
of the total power dissipated by tropical cyclone
winds. SST is sea surface temperature.
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CATARINA The first tropical cyclone in the South
Atlantic in recorded history developed on 25
March 2004 and struck the southern coast of
Brazil in Santa Catarina State. The National
Hurricane Center in Miami estimated that the
storm was a full-fledged, category I hurricane,
with central winds between75 mph and 80 mph(121
kph to 129 kph).
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Cyclone (Hurricane) LarryMarch 20, 2006 Category
5 Strongest Australian cyclone in 30 years
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Cyclone (Hurricane) MonicaApril 24,
2006 Category 5 Strongest Australian cyclone in
34 days
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Cyclone (Hurricane) GonuJune 4, 2007 Category 4
on its way to category 5 The strongest hurricane
in history in the Arabian Sea
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Hurricane Dean hit the Yucatan coast on August
21, 2007 as category 5.
Hurricane Felix hit the Nicaraguan coast on
September 4, 2007 as a category 5 (160 mph winds).
This was the first time in history that two
category 5 storms made landfall in the Atlantic.
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It is very likely that hot extremes, heat
waves, and heavy precipitation events will
continue to become more frequent.
Changes in number of days with heat waves from
UCS Northeast Climate Impacts Assessment
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Number of deaths in Paris heatwave, summer 2003
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Migrations based on summer heat index from UCS
Northeast Climate Impacts Assessment
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From a Royal Society report, Ocean Acidification
Due to Increasing Atmospheric Carbon Dioxide
(2005) - The oceans are already 30 more acid
than before fossil fuel burning started. -
Acidification will kill corals, and probably make
many other species (like squid) extinct. - The
overall effects are unknown - there has been no
period like this in the last 2,000,000 years.
Increasing atmospheric carbon dioxide
concentrations lead to increasing acidification
of the ocean. Projections based on SRES
scenarios give reductions in average global
surface ocean pH of between 0.14 and 0.35 units
over the 21st century, adding to the present
decrease of 0.1 units since pre-industrial times.
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Donner, Simon D., and David Potere, 2007 The
inequity of the global threat to coral reefs,
BioScience, 57, 214-215.
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Global mean sea level changes
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Dynamical processes related to ice flow, not
included in current models but suggested by
recent observations, could increase the
vulnerability of the ice sheets to warming,
increasing future sea level rise.
Understanding of these processes is limited and
there is no consensus on their magnitude.
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Titus, J. G. and C. Richman, 2001, Climate
Research.
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Titus, J. G. and C. Richman, 2001, Climate
Research.
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Titus, J. G. and C. Richman, 2001, Climate
Research.
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SC
NC
Titus, J. G. and C. Richman, 2001, Climate
Research.
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Charleston, SC
Titus, J. G. and C. Richman, 2001, Climate
Research.
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Rahmstorf, Stefan, et al., 2007 Recent climate
observations compared to projections.
Science.Published online 2 February 2007,
10.1126/science.1136843 Dashed lines and gray
shading are 2001 TAR projections. Colored lines
are observations. While CO2 is increasing as
projected, temperature is increasing a little
more than all the scenarios. Sea level closely
follows the upper gray dashed line, the upper
limit referred to by IPCC as including land-ice
uncertainty. Note that the rate of rise for the
last 20 years of the reconstructed sea level is
25 faster than the rate of rise in any 20 year
period in the preceding 115 years.
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Detection Attribution
Projection
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• NCAR simulation ofArctic summer sea ice with
  global warming
• Recent retreat of Arctic sea ice is likely to
  accelerate so rapidly that Arctic Ocean will be
  devoid of ice during summertime as early as 2040.

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Service, Robert, 2004, Science.
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Areas of Human Endeavor That Could Be Affected by
Global Warming Agriculture Electricity
Demand Water Resources Wind Energy
Generation Fisheries Solar Energy Generation Air
Pollution Hydroelectricity Generation Human
Health Ocean Transportation Recreation Air
Transportation Insurance Land Transportation Wetl
ands Political Systems Forestry
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Released in Brussels, April 6, 2007
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In the course of the century, water supplies
stored in glaciers and snow cover are projected
to decline, reducing water availability in
regions supplied by meltwater from major mountain
ranges, where more than one-sixth of the world
population currently lives. Crop productivity is
projected to increase slightly at mid to high
latitudes for local mean temperature increases of
up to 1-3C depending on the crop, and then
decrease beyond that in some regions. At lower
latitudes, especially seasonally dry and tropical
regions, crop productivity is projected to
decrease for even small local temperature
increases (1-2C), which would increase risk of
hunger. Globally, the potential for food
production is projected to increase with
increases in local average temperature over a
range of 1-3C, but above this it is projected to
decrease.
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IPCC Working Group II In the course of the
century, water supplies stored in glaciers and
snow cover are projected to decline, reducing
water availability in regions supplied by
meltwater from major mountain ranges, where more
than one-sixth of the world population currently
lives. Crop productivity is projected to
increase slightly at mid to high latitudes for
local mean temperature increases of up to 1-3C
depending on the crop, and then decrease beyond
that in some regions. At lower latitudes,
especially seasonally dry and tropical regions,
crop productivity is projected to decrease for
even small local temperature increases (1-2C),
which would increase risk of hunger.
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The Chacaltaya glacier and ski lift,
BoliviaSkiing was no longer possible after 2004
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Climate Change Fundamental Questions
3. What should we do about it?
This is a political decision to be made by
society and individuals, and is based on
values. Cannot be answered directly by science,
but mitigation and adaptation need to be informed
by scientific results, for example - the
response to different mitigation choices -
scenarios for implementation of mitigation and
adaptation, such as wind climate for wind
generators, or future climate for agriculture -
assess carbon offset schemes
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REPORT OF THE UNITED NATIONS CONFERENCE ON
ENVIRONMENT AND DEVELOPMENT (Rio de Janeiro, 3-14
June 1992) Annex I RIO DECLARATION ON ENVIRONMENT
AND DEVELOPMENT Principle 15 In order to protect
the environment, the precautionary approach shall
be widely applied by States according to their
capabilities. Where there are threats of serious
or irreversible damage, lack of full scientific
certainty shall not be used as a reason for
postponing cost-effective measures to prevent
environmental degradation.
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The United NationsFramework Convention On
Climate Change 1992 Signed by 194 countries and
ratified by 188(as of February 26, 2004) Signed
and ratified in 1992 by the United States The
ultimate objective of this Convention ... is to
achieve ... stabilization of greenhouse gas
concentrations in the atmosphere at a level that
would prevent dangerous anthropogenic
interference with the climate system.
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How do you define Dangerous Change? Exterminati
on of Animal Plant Species 1. Extinction of
Polar and Alpine Species 2. Unsustainable
Migration Rates Ice Sheet Disintegration Global
Sea Level Rise Regional Climate Change 1. More
Strong Hurricanes 2. Droughts/Floods 3. Threats
to Water and Food Supply A Warming gt1C Risks a
Different Planet.
Partly from Jim Hansen, 11/21/06
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Kyoto Protocol Adopted at the third session of
the Conference of the Parties to the UNFCCC in
Kyoto, Japan, on 11 December 1997. It has been
signed, but not ratified, by the US. Agrees to
limit US greenhouse gas emissions to 93 of the
level of 1990 by 2008-2012. To come into force,
the Kyoto Protocol had to be ratified by at least
55 countries, including Annex I countries
accounting for at least 55 of this
industrialized groups emissions in 1990. The
Kyoto Protocol entered into force on February 16,
2005, after Russia ratified it. As of 16
September 2005, 156 states and regional economic
integration organizations have deposited
instruments of ratifications, accessions,
approvals or acceptances. The total percentage
of Annex I Parties emissions is 61.6.
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Science24 March 2006
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From Jim Hansen, 11/21/06
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From Jim Hansen, 11/21/06
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To avoid warming gt1C - Maximum CO2 450 ppm -
Slightly larger if non-CO2 forcings (e.g.,
methane, black carbon particles) decrease Gas
and Oil Use Most of 450 ppm Limit - Gas and oil
must be stretched via efficiency - Coal and
unconventional fossil fuels must be phased out or
capture CO2 - Future power plants must be
zero-CO2 - Vehicles eventually must be zero-CO2
Partly from Jim Hansen, 11/21/06
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From IPCC Working Group III Stabilization of
equivalent CO2 at a level of 445-535 ppm will
cost less than 0.12 of GNP annually through the
year 2030.
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One Method of Carbon Sequestration
New York Times, May 1, 2007
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The answers are Efficiency hybrid autos,
trucks, and trains, solid state lighting, more
efficient furnaces and appliances Conservation
better insulation, public transportation,
bicycles Renewable Energy solar, wind,
geothermal, biomass (e.g., ethanol, biodiesel,
wood) Carbon Sequestration especially for fixed
coal-burning plants in the U.S., India, and
China. And with biofuels, it will reduce
atmospheric CO2.
WE NEED ALL OF THE ABOVE
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IPCC Working Group III Summary for
Policymakers May 4, 2007
Table from Nature, May 10, 2007, vol 447, p. 121.
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Keith, David, 2001 Geoengineering, Nature, 409,
420.
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Whitesides, George M. and George W. Crabtree,
2007 Don't forget long-term fundamental research
in energy, Science, 796-798.
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Goldemberg, José, 2007 Ethanol for a sustainable
energy future, Science, 808-810.
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Goldemberg, José, 2007 Ethanol for a sustainable
energy future, Science, 808-810.
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Nature, 447, June 28, 2007
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Nuclear power is NOT the answer, for any one of
the following reasons 1. Unsafe operation (poor
NRC oversight, for profit culture, planned and
unplanned releases, fire protection, evacuation
plans) 2. Possibility of catastrophic
accident 3. Possibility of terrorist attack and
radioactive release 4. Not economically
viable 5. Waste disposal problem not solvable in
near future 6. Nuclear weapons proliferation
(fuel processing plant could produce 10-30 U
weapons/yr, waste reprocessing could produce 30
Pu weapons/yr)
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The 2005 Energy Bill OIL GAS SUBSIDIES 6
BILLION COAL SUBSIDIES 9 BILLION NUCLEAR POWER
SUBSIDIES 12 BILLION Oil gas regulatory
rollbacks Repealing the Public Utility Holding
Company Act (PUHCA), one of the most effective
consumer and protection laws governing the power
sector.
Source Public Citizen, http//www.citizen.org/cme
p/energy_enviro_nuclear/electricity/energybill/200
5/articles.cfm?ID13980
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Source American Wind Energy Association,
http//www.awea.org/pubs/factsheets/Subsidy.pdf
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What the US government should do immediately Al
Gore Congressional testimony, March 21, 2007
1. Immediately freeze carbon dioxide emissions
and then begin a program to reduce them by at
least 90 by 2050. 2. Replace the payroll tax for
Social Security and Medicare with a tax on
pollution, particularly carbon dioxide. 3. Use a
portion of the tax on pollution to help
low-income individuals adapt as carbon emissions
are reduced. 4. Work towards de-facto compliance
with the Kyoto Protocol to the United Nations
Framework Convention on Climate Change, and
create a new, strong international treaty with a
starting date of 2010 instead of 2012. 5. Enact a
moratorium on the construction of any new
coal-fired power plants that are not compatible
with carbon capture and sequestration.
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What the US government should do immediately Al
Gore Congressional testimony, March 21, 2007
6. Create an Electranet, a smart grid in which
power generation is widely distributed.
Homeowners and small businesses could use solar
and wind energy generators and sell that energy
into the grid at a rate that is determined by the
market. 7. Raise Corporate Average Fuel Economy
(CAFE) standards for automobiles, and set energy
standards for other industries. 8. Set a date for
a ban on incandescent light bulbs. 9. Create a
Connie Mae, a carbon-neutral mortgage
association that would help homebuyers pay for
energy reduction measures such as insulation and
energy-efficient windows that can have high
upfront expenses. 10. Have the Securities and
Exchange Commission (SEC) require the disclosure
of carbon emissions in corporate reporting.
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What the you can do immediately
- Support legislation that will help solve the
problem, both in New Jersey and in Congress. -
Vote for legislators who will help solve the
problem. - Install solar cells, with New Jersey
helping to pay the bill. - Use less energy Less
driving (telecommute, bike, train, bus) Smaller
car/hybrid Insulate your house Cooler house in
winter, warmer in summer Buy local
products Compact fluorescent bulbs Less meat
(energy, methane) Recycle Biodiesel
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The New York Times, Oct. 8, 2006
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Explanation of gas price 1.20 fuel,
refining 0.27 distribution 0.50 profit 0.25 sta
te highways 0.10 federal highways 4.05 military
0.69 local air pollution 0.57 climate change
0.00 marketing 7.63 Total
Gallons
13.563
Price per gallon
7.639
Total
103.61
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Copulos (2006)
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No regrets policies. Reduced usage of energy
will have many positive benefits to society, even
if projected global warming turns out to have
been exaggerated (which is just as likely as that
the warming turns out to have been
underestimated). We would have cleaner air,
less acid rain, greater visibility in the
atmosphere, cooler central regions of cities,
more trees, and less dependence on foreign oil
supplies.
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The words of the prophets are written on the
subway walls Sounds of Silence (Simon and
Garfunkel, 1966)
Very Likely
Photograph by Warren Washington