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GLOBAL CLIMATE CHANGE: WHY THE SKEPTICS ARE WRONG

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Title: GLOBAL CLIMATE CHANGE: WHY THE SKEPTICS ARE WRONG


1
GLOBAL CLIMATE CHANGE
WHY THE SKEPTICS ARE WRONG
JUNE 27, 2006
John Harte
University of
California, Berkeley
2
The increase in atmospheric carbon dioxide is
primarily due to world energy consumption and
secondarily due to deforestation.
3
The greenhouse gases trap outgoing heat and
radiate it back to the surface
Sunlight
Greenhouse gases
Heat
Heat
4
The central prediction of current climate models
What is the effect on global average surface
temperature of doubling the
atmospheric concentration of carbon dioxide?
  • The direct effect of heat absorption by the CO2
    1.2 oC
  • The indirect (feedback) effects
    0.3 to 3.4 oC
  • melting ice and snow increases absorption
    of sunlight (ice-albedo effect)
  • warmer air holds more water vapor,
    another greenhouse gas
  • warmer air results in different cloud
    characteristics

TOTAL
1.5 to 4.6oC
5
Should we worry about 4 oC change?
Temperatures During the Past Ice Age
oF
oC
6oC
Thousands of years ago
6
Climate Models Have Good Predictive Power….
0.7oC increase in past Century Up to 5oC
this century
7
Fingerprint of Global Warming
Models predict, and the data show that
  • Stratosphere cools as surface warms
  • Temperature rises faster at night than day
  • Temperature rises faster in winter than summer
  • High latitudes warm more than low latitudes

If global warming were caused by a brightening
sun, then the stratosphere would warm and
temperature rise would be greatest in daytime
8
  • We are entering
  • uncharted territory
  • in human experience.
  • If nothing is done to slow greenhouse gas
    emissions. . .
  • CO2 concentrations will be more than 700 ppm by
    2100
  • Temperatures may be warmer than any time since
    the dinosaurs!

2100
today
Source OSTP
9
IMPACTS OF GLOBAL WARMING
Greater intensity, frequency duration of
harmful summer heat waves Sea level rise
of at least ½ m by 2100 loss of some island
nations Melting of glaciers and sea ice
loss of alpine and arctic habitat polar
bears! Reduced snow pack loss of irrigation
water for crops Coral reef degradation due
to bleaching Near unanimity among scientists
active in the field high level of confidence in
predictions
10
MORE IMPACTS OF GLOBAL WARMING
Increased intensity and possibly frequency of
hurricanes and droughts Reduced crop yields
because of extreme events and persistent
drought Increased threat of major wildfires
Consensus exists on the underlying science
and facts work needed to sharpen predictions
11
AND STILL MORE IMPACTS
Sea level rise up to 40 feet because of
Greenland and Antarctica ice melt (bi-polar
disorder) catastrophic damage to
huge numbers of people and to much coastal
infrastructure Extinction
episode comparable to K-T boundary catastrophic
loss of ecosystem services Major spread of
infectious tropical and subtropical diseases to
the mid-latitudes
Agreement that the problem is real and of
serious importance data gaps and some basic
science still to be resolved
12
Prevailing Myths about Global Warming
Pre-historical climate change far exceeds the
anticipated changes in the next 100 years, so no
need to worry. Variation in sunlight probably
explain the recent warming trend Satellite data
contradict the evidence for a warming trend. A
cooling trend during 1940-1970 contradicts the
global warming concept The world should welcome
global warming because it will help moderate the
impacts of the impending ice age. Global warming
will be good for agriculture CO2
enrichment Global warming theory has never been
proven! Reducing emissions will severely damage
our economy
13
Future energy policy will determine this
Global average surface temperature is heading not
only far outside the range of variation of the
last 1000 years but outside the range experienced
in the tenure of Homo sapiens on Earth.
This warming has already occurred
1000
2100
Year
14
The Climate Challenge
Gigatons Carbon Emitted per Year
Doubled emissions from business as usual
14
The Stabilization Wedges
Emissions Stabilization
7
Current emissions
Climate Stabilization
0
1950
2000
2050
15
There are more than 7 wedges to choose from
Here are 15 candidates.
16
The policy issue in brief
  • Society has three options
  • Prevention, which means measures to reduce the
    pace magnitude of the changes in global climate
    being caused by human activities.
  • Examples of prevention include reducing
    emissions of GHG, enhancing sinks for these
    gases, and geoengineering to counteract the
    warming effects of GHG.
  • Adaptation, which means measures to reduce the
    adverse impacts on human well-being resulting
    from the changes in climate that do occur.
  • Examples of adaptation include changing
    agricultural practices, strengthening defenses
    against climate-related disease, and building
    more dams and dikes. But its a moving target!
  • Suffering the adverse impacts that are not
    avoided by either mitigation or adaptation.

17
Approaches to prevention
  • Improve energy use efficiency (e.g. hybrids)
  • Alter life styles to use less energy (e.g. walk
    to work)
  • Use cleaner fossil fuels (e.g., gas not coal)
  • Solar energy (wind, photovoltaics, biomass)
  • Sequester carbon from fossil fuels underground
  • Nuclear energy

18
Approaches to prevention (continued)
  • TYPES OF POLICY MEASURES FOR PREVENTION
  • regulations (such as emission standards) and
    incentives (such as taxes or tax relief) to
    promote cleaner energy
  • government funding for RD to insure that
    technical options are available in the
    marketplace
  • incentives for private investment in research,
    development, demonstration.
  • IN ADDITION, THE IMPORTANCE OF CONSUMER
    PRESSURE SHOULD NOT BE UNDERESTIMATED

19
The renewable option Is it real?
  • SUNLIGHT ½ of the worlds land area receives
    enough sunlight, converted to useable energy at
    20 efficiency, to meet the worlds rate of
    energy use in 2005.
  • WIND Wind power estimated to be harvestable
    from windy sites covering 2 of Earths land
    surface is about twice world electricity
    generation in 2005.
  • BIOMASS Energy crops grown at the average
    terrestrial photosynthetic yield on 10 of land
    area (equal to whats now used for agriculture)
    and converted to liquid biofuels at 50
    efficiency would provide a little over half of
    world oil use in 2005.
  • Renewable energy potential is immense, but big
    concerns about biomass
  • habitat loss


    To replace US gasoline, need to grow
    corn-for-ethanol on the entire combined area of
    Nebraska, Kansas, Oklahoma, Arkansas, Missouri,
    Iowa!
    photovoltaics gives a 20x
    advantage wrt land use, and dont need prime land
  • competition between ethanol production and food
    production
  • resources water, fertilizer, herbicides,
    pesticides for biomass,
  • unanticipated climate effects
  • Non-CO2 greenhouse gases from biomass
    production
  • albedo of land surface

20
SUMMARY (1) The consensus view 1. There is a
scientific consensus that human-caused global
warming is a serious problem a. its effects
are already observed, b. if preventive steps
are not taken, its future consequences for human
well being will be large and detrimental 2.
Many attractive options exist for reducing carbon
dioxide emissions first and foremost is
improving efficiency of energy use.
21
  • SUMMARY (2)
  • A personal view
  • Global warming is an opportunity as well as a
    problem
  • it provides us with a wonderful excuse to
  • a. Restore to world leadership our dying
    automobile industry
  • Reduce our dependence on foreign oil and the
    costs of maintaining that dependence
  • Reduce levels of smog and other air pollutants
    that result from fossil fuel burning and that
    impair our health
  • Save industry and consumers billions of by
    becoming more efficient in the use of energy

Solving global warming will make us richer,
healthier, and more peaceful…what a deal!
22
(No Transcript)
23
The Vostok core data imply additional feedback
Milankovitch mechanisms are the forcing, and thus
the time keeper, but their magnitude is too weak
to explain the magnitude of the huge climate
variability CO2 release during slight warming
must cause more warming! And CO2 uptake during
slight cooling must cause more cooling.
This feedback is not incorporated in our current
GCMs and suggests that future warming may be
worse than we think
24
How much prevention is needed? (continued)
  • Until a few years ago, many analysts and groups
    were suggesting a target of about 3C.
  • This was a compromise perhaps the highest
    value that might be tolerable (taking into
    account potential for adaptation) and at the same
    time the lowest value that might be achievable
    (taking into account the known mitigation options
    and their costs).
  • Recent insights about impacts have led many
    analysts groups, over the past few years, to
    argue for a tighter target, around 2C.
  • This would mean confining the sum of human
    influences to the equivalent of CO2s reaching
    400-450 ppmv.
  • Some analysts doubt that so low a target can be
    achieved.

25
How much prevention is needed?
  • The conclusion of most analysts is that
    we are going to need
  • as much prevention as we can get,
  • as quickly as we can get it.

26
GLOBAL CLIMATE CHANGE
WHY THE SKEPTICS ARE WRONG
JUNE 27, 2006
John Harte University of California, Berkeley
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