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Hot House Global Climate Change and the Human Condition

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Title: Hot House Global Climate Change and the Human Condition


1
Hot HouseGlobal Climate Change and the Human
Condition
Robert G. Strom, Professor Emeritus Department of
Planetary Sciences and Lunar and Planetary
Laboratory University of Arizona
2
Introduction
  • The Science Consensus
  • and
  • American Attitudes on Global Warming

3
Reliability of Global Warming Parameters
  • Global warming
  • Rise in greenhouse gases
  • Cause of global warming
  • Long term consequences of global warming
  • Solution to the problem
  • Prospects of implementing a solution
  • Firmly Established
  • Firmly Established
  • Firmly Established
  • Many known, but other consequences probable
  • Well understood
  • Extremely uncertain

4
Science Organizations that Support the Findings
on Global Warming and its Human Cause
  • U.S. National Academy of Sciences
  • American Geophysical Union
  • American Meteorology Society
  • American Association for the Advancement of
    Science
  • British Royal Society
  • At least 27 other international scientific
    societies

5
Figure Courtesy of IPCC
6
IPCC Main Conclusions
  • Global warming is unequivocal.
  • Human-caused emissions of greenhouse gases are
    the primary cause of global warming.

7
Main Statements of World Science Community to G8
Nations (2008)
  • A concrete timetable and coordinated plan to
    build a substantial number of carbon capture and
    storage demonstration plants.
  • Better preparedness for problems climate change
    may cause, including assessments of the
    vulnerability of developing countries.
  • A faster transition to a low-carbon economy,
    boosted by the promotion of greener lifestyles.
  • Heavy investment in carbon-removing technology
    and ways to "leapfrog" from fossil fuels to
    low-carbon energy sources.
  • Governments to support research on greenhouse gas
    reduction and climate change impact.

8
American Attitudes on Global Warming
9
Pew Research Center (July 2006) and ABC News
(March 2006) Polls
  • 70 believe there is solid evidence of global
    warming but only 41 believe it is caused by
    human activities. (Pew Research Center)
  • 64 perceive a lot of disagreement among
    scientists on global warming. (ABC)
  • Only 33 think scientists agree that global
    warming has begun. (ABC)

10
Americans are much less concerned about global
warming than others
  • How personally concerned are you about global
    warming? (Pew Research Center)
  • Those who said a great deal
  • Japan ---- 66
  • Spain ---- 51
  • France --- 46
  • China ---- 20
  • U.S.A. --- 19

11
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15
Part 1
  • Fundamentals

16
Climate Shift and Temperature
17
Natural Variations of Climate during Warming
18
The Greenhouse Effect
19
Small changes in the global average temperature
result in large climate changes
  • A 5 C drop in the global average temperature
    places us in the depths of an Ice Age.
  • An 8 C rise in the global average temperature
    places us near the top of a Hot House.

20
Greenhouse Gases Emitted by Human Activity
  • Carbon Dioxide - CO2 (56)
  • Methane - CH4 (16)
  • Tropospheric Ozone - O3 (12)
  • Halocarbons (11)
  • Nitrous Oxide - N2O (5)

21
Climate Drivers
22
Part 2
  • Past Climates

23
Generalized Climates for the Past 3 Billion Years
24
Climate Change During Past 180 Million Years
25
The Paleocene-Eocene Thermal Maximum (PETM)
26
The Pliocene/Pleistocene Ice House
27
Causes of Climate Change
  • Abundance of Greenhouse Gases
  • Major Volcanic Eruptions
  • Large Asteroid or Comet Impact
  • Change in Suns Irradiance
  • Change in Ocean Circulation
  • Continental Drift
  • Change in Earths Motions

Red main cause of current global warming
28
Part 3
  • Atmospheric Greenhouse Gas Levels

29
Greenhouse Gases for the Past 650,000 Years
30
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31
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32
Measured Increase in CO2, Nitrous Oxide, Methane
and CFCs Since 1979
33
Recent CO2 Increase (1959 - 2007)
34
Residence Time in the Atmosphere of a Pulse of CO2
35
Part 4
  • Rising Temperatures

36
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37
Temperatures from Proxies and Instruments for
Last 1,800 Years
  • The current temperature rise is unprecedented
  • It coincides with the Industrial Revolution and
    the exponential population growth
  • It also coincides with the rapid rise in
    greenhouse gas emissions

38
Radiative and Net Climate Forcing(1880-2006)
39
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40
Aerosols
Aerosols
41
Temperature, CO2 Concentrations and Carbon
Emissions
42
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43
Temperature Increase 1992-2004
  • The yellows and reds on these world maps are
    positive (warm) anomalies while blues are
    negative (cool) anomalies.
  • The greatest amount of heating has occurred
    generally in the Northern Hemisphere and
    specifically in the Arctic regions.

44
Temperature Anomaly for 2007
45
Temperature Anomaly at CO2 Stabilization Relative
to 1800
46
Only Human-caused Greenhouse Gas Emissions Can
Account for Global Warming
  • The black line is the observed temperature rise.
  • The red area is computer simulations of all
    emissions, including human.
  • The blue area is computer simulations of only
    natural emissions and the increase in solar
    activity.

47
The Warming Oceans
48
Earths Heat Gain During the Past 50 years (1021
Joules)
  • Oceans 145 (84)
  • Continents 10.4 (6)
  • Earths Ice 8.1 (5)
  • Atmosphere 6.6 (4)

A joule is a unit of heat energy
49
What Global Average Temperatures Become Critical
and Catastrophic for Humans?
  • The current best estimate is 2 C above the
    1951-1980 average is potentially critical. About
    4 C is potentially catastrophic. The Earth is
    now 0.57 C above that average.
  • When the CO2 abundance reaches 450 ppm the
    temperature anomaly will eventually reach a
    minimum of 2 C. At 650 ppm it will eventually
    reach a minimum of 4 C.
  • The current abundance is 385 ppm and rising at a
    rate of 2 ppm/year, and this rate is increasing.
  • We have about 30 years to stabilize the
    greenhouse gas abundance by cutting emissions
    70 (80 for CO2 only). Even at todays
    abundance the temperature anomaly will rise
    another 0.6 to 1 C in about 40 years with
    serious consequences.

50
WHAT IS CRITICAL AND WHAT IS CATASTROPHIC?
  • CRITICAL --- serious drop in food production,
    serious water shortages, significant sea level
    rise, political unrest, major drop in world GDP,
    major animal extinctions and millions of human
    deaths. Third-world countries, e.g. Africa, are
    affected most, including large human migrations.
  • CATASTROPHIC --- mass extinction event (50
    species extinction), major sea level rise, mass
    starvation, political and economic chaos, 50
    human deaths (3 billion people). Probably the
    end of civilization as we know it today.

51
Possible CO2 Concentrations and Temperature
Increases
52
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53
Past and Future Temperatures
54
Part 5
  • Human-caused Greenhouse Gas Emissions

55
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56
Emissions Warning
  • Since 2000, the growth of carbon emissions from
    fossil fuels has tripled compared to the 1990s
    and is exceeding the predictions of the highest
    IPCC emission scenarios.
  • During the 1990s the emissions growth rate
    increased 1.3 per year, but from 2000-2006 it
    increased 3.3 per year.
  • The efficiency of natural sinks has decreased by
    18 over the last 50 years, and will continue to
    do so in the future. The longer we wait to reduce
    emissions, the larger the cuts needed to
    stabilize atmospheric CO2.
  • All of these changes characterize a carbon cycle
    that is generating stronger climate change much
    sooner than expected.

57
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58
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59
Amazon Rainforest Drying and Burning due to
Deforestation and Climate Change Drought
60
Greenhouse Gas Emissions
  • Today human-activities are emitting 36 billion
    metric tons of CO2 each year. Since 15-20
    billion tons (42 - 55) are absorbed by sinks
    (oceans and land), 21-16 billion tons are added
    to the atmosphere each year.
  • The present concentration of greenhouse gases has
    not been exceeded during at least the past
    800,000 years, and probably the past 20 million
    years.
  • The current rate of increase of CO2 (2.14 ppm per
    year) is unprecedented at least during the last
    20,000 years and probably much longer. The rate
    is increasing.
  • The global average temperature is rising faster
    than anytime during at least the past 10,000
    years.

61
The Root Cause
62
Estimated Population Growth from 2000 to 2025
63
Atmospheric CO2 and Population Growth
64
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65
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66
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67
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68
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69
1751-2006 CUMULATIVE CO2 Emissions
70
Sources of Present Emissions of CO2 and in
Todays Atmosphere
71
Coal The Worst CO2 Emitter
  • One mid-sized coal-fired power plant
    (500-megawatts) emits about 3.5 million tons of
    CO2 annually.
  • This is equivalent to 625,000 additional cars on
    the road traveling 12,000 miles per year.
  • Currently (2007), U.S. utility companies have
    proposed building 185 new coal-fired power plants
    (10 in operation, 32 under construction, and 90
    in early development).
  • China is building, on average, 1 coal-fired power
    plant each week.

72
U.S. Electricity Generation and CO2 Emissions
73
2005 and Projected Coal Use by Country or Region
74
Part 6
  • Consequences

75
Some Current Consequences of Global Warming
  • More Severe Heat Waves of Greater Duration
  • Sea-level Rise and Ocean Acidification
  • Glaciers, Ice Sheet and Permafrost Melting
  • Spreading Disease
  • Plant and Animal Range Shifts Plus Extinctions
  • Coral Reef Degradation
  • More Severe and Frequent Weather Events
  • More Severe and Frequent Flooding
  • More Severe Droughts and Fires

76
The Melting Earth
Part 6a
77
Mountain Glaciers
  • Over 95 of mountain glaciers are shrinking

78
Melting Glaciers
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81
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82
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83
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84
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85
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86
Two Ice Sheets
87
The Arctic
88
Arctic Summer Sea Ice Record Minimum (2007)
89
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90
The Worst Scenarios of the IPCC Underestimated
the Amount of Summer Sea Ice Decline
91
Computer Model Simulation vs. Observed Decline of
Arctic Summer Sea Ice
92
Age of Artic Sea Ice is Decreasing
93
How Will the Polar Bears Fare Under Global
Warming?
94
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95
Greenland Melting (1992-2005)(Volume loss (2005)
240 km3 per year)
96
Greenland Ice Sheet Melting
97
Greenland Ice Sheet Instability
98
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99
Decline in the Area of Arctic Permafrost
100
Projected Temperature Increase and Permafrost
Declineby the 2090s
101
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102
Melting Permafrost in Siberia (Siberian CO2
equivalent release from land was 235 million
metric tons per year in 2006)
103
Accelerated Permafrost Melting
  • The 2007 Arctic warming that caused the rapid and
    extensive sea ice decline accelerated the melting
    of permafrost. The accelerated warming extends up
    to 1500 km inland.
  • If the recent trend in sea ice loss continues it
    may triple Arctic warming, causing large
    emissions of carbon dioxide and methane from the
    tundra.
  • Simulated western Arctic land warming trends
    during rapid sea ice loss are 3.5 times greater
    than predicted 21st century climate-change
    trends.
  • This could lead to a non-linear catastrophic
    warming.

104
Methane Hydrate A Wake-up Call
105
Methane Hydrate Ice Burns
106
The Methane Hydrate Danger 1
  • The frozen Arctic continental shelf off Siberia
    has started to thaw and release long-stored
    methane gas. The consequence could be an
    unstoppable near- to long-term catastrophic
    warming of the Earth.
  • In this region the carbon content of the methane
    hydrates is estimated at 540 billion metric tons,
    or the CO2 equivalent of 1.98 trillion metric
    tons.
  • Methane hydrate in the shelfs sediments is
    perilously close to thawing. Three to 12 km from
    the coast the ocean sediment temperature is just
    below freezing at -1 to -1.5 C. Permafrost on
    land is as cold as -12.4 C.

107
The Methane Hydrate Danger 2
  • The permafrost has grown porous and is becoming
    unstable. The shelf has already become a source
    of methane passing into the atmosphere. If this
    Siberian permafrost-seal thaws completely and all
    the stored gas escapes, the methane content of
    the planet's atmosphere would increase
    twelve-fold leading to a catastrophic rise in
    temperature.
  • The Arctic Ocean will get warmer as the summer
    sea ice continues to recede and the ocean becomes
    ice-free for extended periods. This could result
    in the temperature of the continental shelf
    sediments rising above freezing, releasing vast
    quantities of methane to the atmosphere.

108
Methane Beginning to Increase After 8 Years of
Stability
  • During the past 8 years the methane abundance has
    been relatively stable due to industrial changes
    in Russia, changes in the methods of rice
    farming, and methane capture from landfill sites.
  • In 2007 the world methane abundance increased
    0.5.
  • Based on carbon isotope analyses the methane is
    of biogenic origin.
  • The source is probably release from melting
    permafrost, and possibly the Siberian Arctic
    continental slope methane hydrates.
  • We may now be entering a non-linear climate
    response.

109
Antarctica
110
First Year and Number of Days of Melting in
Antarctica
111
Antarctic Temperature Changes Between 1981 and
2007
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113
Larson B Ice Shelf Collapse (2002)
114
Breakup of the Wilkins Ice Shelf (2008)
In the past 50 years, the western Antarctic
Peninsula has experienced the biggest temperature
increase on Earth, rising by 0.5 degree Celsius
(0.9 degree Fahrenheit) per decade. Satellite
images indicate that the Wilkins began its
collapse on February 28, 2008 data revealed that
a large iceberg, 41 by 2.5 kilometers (25.5 by
1.5 miles), fell away from the ice shelfs
southwestern front, triggering a runaway
disintegration of 405 square kilometers (160
square miles) of the shelf interior.
115
Sea Level Rise
Part 6b
116
Sea Level Rise 1993-2006
117
Regional Patterns of Sea Level Change 1993-2007
118
Eroding Beaches on East Coast
119
Projected Home Destruction from Rising Sea Level
  • Projected minimum home destruction in next 30
    (outer white line) and 60 years (inner white
    line) in S. Bethany, Delaware.
  • House destroyed from beach erosion in West
    Hampton, NY.

120
High Tide in Tuvalu Islands
121
Affects of a Small Sea Level Rise on the Nile
Delta
  • For a 0.5-meter increase, 3.8 million people are
    displaced and 1,800 km2 of cropland is lost.
  • For a 1-meter increase, 6.1 million people are
    displaced and 4,500 km2 of cropland is lost.
  • In both cases, Alexandria, Port Said and several
    smaller towns are lost.

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125
Southeastern Seaboard After a 6 Meter Sea Level
Rise
126
Alaska and gulf coast area after a 1 to 6 meter
sea level rise
127
East Asia and Southeast Asia after a 1 to 6 meter
rise in sea level
128
North Europe and Mediterranean after a 1 to 6
meter sea level rise
129
South Asia and South America after a 1 to 6 meter
sea level rise
130
Weather Changes
Part 6c
131
Change in Precipitation
132
Number of Floods by Continent and Decade From
1950 to 2000
133
The European Heat Wave of 2003
  • During two weeks in August 2003 Europe
    experienced the highest temperatures in at least
    the past 500 years.
  • Parts of Europe had temperatures of 41 C or 107º
    F.
  • The heat wave resulted in about 35,000 deaths,
    almost half of which were in France.
  • Under current greenhouse gas emissions, these
    temperatures will be the summer norm in about 40
    years.

134
Observed European Temperature Rise and Computer
Projections
135
Increase in Hurricane Strength
136
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137
About 150,000 people die each year (2000) from
the effects of global warming
138
Temperature Effects in the United States
Part 6d
139
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140
Projected U.S. Temperature Increase (2040-2060)
141
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142
U.S. Rainfall Anomaly Jan.-August 2007
143
43 of U.S. in Drought Conditions in Oct. 2007
144
The Future
Part 7
145
Positive Feedbacks to Global Warming
  • Warming oceans and soils are absorbing less CO2,
    so more CO2 is accumulating in the atmosphere.
  • Melting permafrost is now emitting CO2 and
    methane the more melting the greater the
    emission.
  • The warming methane hydrates on the Siberian
    continental shelf are beginning to emit methane
    and CO2.
  • The decreasing ice and snow cover is exposing
    more dark surfaces causing more surface and
    atmospheric heating.
  • A warming atmosphere holds more water vapor (a
    strong greenhouse gas) increasing the temperature.

146
Model Future Water Vapor Increase
147
Positive Feedbacks Can Lead to a Non-linear
Climate Response
148
The 800 lb Gorilla Nobody Wants to Talk About
ABRUBT CLIMATE CHANGE
  • Some large natural climate changes have occurred
    abruptly.
  • In some instances, the average global temperature
    has risen or fallen 8º C in less than 10 years,
    and at least one in as little as 5 years. An
    increase of 6 C in this century would be
    considered an abrupt climate change.
  • The trigger for the abrupt temperature rises is
    not well understood but probably involves a
    catastrophic release of methane and carbon
    dioxide.
  • Global warming could trigger an abrupt climate
    change. If this happened its effects would
    certainly be catastrophic. The recent accelerated
    melting of permafrost and increased atmospheric
    methane could be the beginning of an abrupt
    climate change.

149
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150
Inertia in Action
  • CFCs have decreased dramatically during the past
    20 years.
  • The ozone hole in 2006 was as large as ever
    because of the long lifetime of CFCs in the
    stratosphere and continuing emissions.
  • It will take about 70 years for the ozone hole to
    disappear.

151
Carbon Emissions for Peak CO2 Stabilization
152
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155
Summary
156
To Date Global Warming Mitigation Has Been a
FAILURE
157
Important Points 1
  • Global warming is an extremely serious problem
    that requires the worlds (primarily
    industrialized nations) immediate action to curb
    greenhouse gas emissions.
  • Currently (2007) CO2 emissions are increasing at
    a rate of 3.3 per year. Keeping the atmospheric
    abundance below the critical level of 450 ppm
    will probably be impossible without extraction
    from the atmosphere. Even cutting emissions
    enough to prevent a potentially catastrophic
    level of 650 ppm will be difficult, but possible
    if we act now in a vigorous manner.
  • Currently it is unlikely that the Kyoto Protocol
    extension will be able to keep the CO2 abundance
    under the critical level.

158
Important Points 2
  • China surpassed U.S. greenhouse gas emissions in
    2007 and is now the greatest emitter. If the U.S.
    and China do not drastically reduce emissions,
    the situation is hopeless. Together they account
    for about 40 of the total emissions.
  • Because of the inertia of the climate system the
    global average temperature will rise at least
    1.5 C this century putting us above the critical
    level, even if we completely stopped all
    greenhouse gas emissions by 2050.
  • The worlds grandchildren will pay dearly for our
    inaction.

159
Part Of The Generation That Is Depending On Our
Actions.
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