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Climate Change

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Chapter 19 Climate Change and Ozone Depletion (we can get along!) – PowerPoint PPT presentation

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Title: Climate Change


1
Chapter 19
  • Climate Change
  • and
  • Ozone Depletion

(we can get along!)
2
Mount Pinatubo erupts!
the Phillipines
1991
Figure 20-1
3
The effects of the eruption were felt worldwide.
It ejected roughly 10 billion metric tonnes (10
cubic kilometres) of magma, and 20 million tons
of SO2, bringing vast quantities of minerals and
metals to the surface environment. It injected
large amounts of aerosols into the
stratospheremore than any eruption since that of
Krakatoa in 1883. Over the following months, the
aerosols formed a global layer of sulfuric acid
haze. Global temperatures dropped by about 0.5 C
(0.9 F), and ozone depletion temporarily
increased substantially. -Wikipedia
4
Core Case Study Studying a Volcano to Understand
Climate Change
  • A NASA scientist correctly predicted that the
    1991 Philippines explosion would cool the average
    temperature of the earth by 0.5Co over a 15 month
    period and then return to normal by 1995.

Figure 20-1
5
Core Case Study Studying a Volcano to Understand
Climate Change
  • The NASA climate change model was correct.
  • The Mt. Pinatubo model prediction success
    convince scientists and policy makers that
    climate model projections should be taken
    seriously.
  • Other climate models have shown that global
    temperatures are likely to rise several degrees
    during this century.

6
Chapter Overview Questions
  • How have the earths temperature and climate
    changed in the past?
  • How might the earths temperature and climate
    change in the future?
  • What factors influence the earths average
    temperature?
  • What are some possible beneficial and harmful
    effects of a warmer earth?

7
Chapter Overview Questions (contd)
  • How can we slow projected increases in the
    earths temperature or adapt to such changes?
  • How have human activities depleted ozone in the
    stratosphere, and why should we care?

8
PAST CLIMATE AND THE GREENHOUSE EFFECT
  • Over the past 900,000 years, the troposphere has
    experienced prolonged periods of global cooling
    and global warming.
  • For the past 1,000 years, temperatures have
    remained fairly stable but began to rise during
    the last century.

9
PAST CLIMATE AND THE GREENHOUSE EFFECT
Figure 20-2
10

Average temperature over past 900,000 years
Average surface temperature (C)
Thousands of years ago
Fig. 20-2a, p. 465
11

Average temperature over past 130 years
Average surface temperature (C)
Year
Fig. 20-2b, p. 465
12

Temperature change over past 22,000 years
Agriculture established
Temperature change (C)
End of last ice age
Average temperature over past 10,000 years 15C
(59F)
Years ago
Fig. 20-2c, p. 465
13

Temperature change over past 1,000 years
Temperature change (C)
Year
Fig. 20-2d, p. 465
14
From website Logicalscience. com
15
(No Transcript)
16
How Do We Know What Temperatures Were in the Past?
  • Scientists analyze tiny air bubbles trapped in
    ice cores learn about past
  • troposphere composition.
  • temperature trends.
  • greenhouse gas concentrations.
  • solar, snowfall, and forest fire activity.

Figure 20-3
17
(No Transcript)
18
Ice Core Analysis
19
Ice Core Analysis
20
National Ice Core Laboratory
21
Ice Core Analysis
A thin cut slice of an ice core.
22
How Do We Know What Temperatures Were in the Past?
  • In 2005, an ice core showed that CO2 levels in
    the troposphere are the highest they have been in
    650,000 years.

Figure 20-4
23

384 ppm in 2007
Concentration of carbon dioxide in the atmosphere
(ppm)
Carbon dioxide
Variation of temperature (C) from current level
280 ppm in 1725
Temperature change
End of last ice age
Thousands of years before present
Fig. 20-4, p. 466
24
The Natural Greenhouse Effect
  • Four major factors shape the earths climate
  • The sun.
  • Greenhouse effect warms the earths lower
    troposphere and surface because of the presence
    of greenhouse gases.
  • Oceans store CO2 and heat, evaporate and receive
    water, move stored heat to other parts of the
    world.
  • Natural cooling process through water vapor in
    the troposphere (heat rises).
  • Evaporation cools the Earths surface
  • Condensation in clouds releases heat in upper
    troposphere

25
Major Greenhouse Gases
  • The major greenhouse gases in the lower
    atmosphere are, IN ORDER
  • water vapor- most important greenhouse gas
  • carbon dioxide- greatest effect from human
    activities
  • Methane- CH4 -more powerful greenhouse gas per
    molecule than CO2, but less of it than CO2
  • nitrous oxide- N2O -comes from fertilizers and
    planting rice

26
Major Greenhouse Gases
  • The major greenhouse gases in the lower
    atmosphere are
  • water vapor carbon dioxide Methane nitrous
    oxide.
  • These gases have always been present in the
    earths troposphere in varying concentrations.
  • Fluctuations in these gases, plus changes in
    solar output and Earths Mankelovich cycles are
    the major factors causing the changes in
    tropospheric temperature over the past 400,000
    years.

27
Major Greenhouse Gases
  • Increases in average concentrations of three
    greenhouse gases in the troposphere between 1860
    and 2004, mostly due to
  • Fossil fuel burning (CO2 CH4)
  • Deforestation (CO2 N2O)
  • Agriculture (N2O)

Figure 20-5
28
384 ppm in 2007
280 ppm in 1725
Fig. 20-5a, p. 467
29
Fig. 20-5b, p. 467
30
Fig. 20-5c, p. 467
31
CLIMATE CHANGE AND HUMAN ACTIVITIES
  • Evidence that the earths troposphere is warming
  • The 20th century was the hottest century in the
    past 1000 years.
  • The 10 hottest years since 1861 have been since
    1990

32
CLIMATE CHANGE AND HUMAN ACTIVITIES
  • Since 1900, the earths average tropospheric
    temperature has risen 0.6 C.
  • Over the past 50 years, Arctic temperatures have
    risen almost twice as fast as those in the rest
    of the world.
  • Glaciers and floating sea ice are melting and
    shrinking at increasing rates.

33
CLIMATE CHANGE AND HUMAN ACTIVITIES
  • Warmer temperatures in Alaska, Russia, and the
    Arctic are melting permafrost, releasing more CO2
    and CH4 into the troposphere (feedback loop)
  • During the last century, the worlds sea level
    rose by 10-20 cm, mostly due to runoff from
    melting of land-based ice and the expansion of
    ocean water as temperatures rise.

34
The Scientific Consensus about Future Climate
Change
  • There is strong evidence that human activities
    will play an important role in changing the
    earths climate during this century.
  • Coupled General Circulation Models (CGCMs)
    couple, or combine, the effects of the atmosphere
    and the oceans on climate.

35
Coupled General Circulation Model of the Earths
Climate
  • Simplified model of major processes that interact
    to determine the average temperature and
    greenhouse gas content of the troposphere.

Figure 20-6
36
Factors that cool
Factors that warm
Troposphere
Ice and snow cover
Shallow ocean
Land and soil biota
Natural and human emissions
Deep ocean
Stepped Art
Fig. 20-6, p. 469
37
Measured and projected changes in the average
temperature of the atmosphere (2005).
  • ? 0.6 C since 1900
  • Consensus projection is 5 C by 2100 if we do
    nothing
  • Consensus is 4 C could threaten civilization as
    we know it

Figure 20-7
38

Most recent data suggests that temperatures are
increasing even faster than the worst-case 2007
IPCC estimates
Fig. 20-7, p. 470
39
Why Should We Be Concerned about a Warmer Earth?
  • A rapid increase (non-linear response pattern) in
    the temperature of the troposphere during this
    century would give us little time to deal with
    its harmful effects.
  • As a prevention strategy scientists urge to cut
    global CO2 emissions 50 over the next 50 years.
    50/50
  • This could prevent changes in the earths climate
    system that might last for tens of thousands of
    years (due to many positive feedback loops)

40
FACTORS AFFECTING THE EARTHS TEMPERATURE
  • Some factors can amplify (positive feedback) and
    some can dampen (negative feedback) projected
    global warming.
  • There is uncertainty about how much CO2 and heat
    the oceans can remove from the troposphere and
    how long the heat and CO2 might remain there
    (feedback?)
  • Warmer temperatures create more clouds that could
    warm or cool the troposphere (feedback?).

41
Human Effects on the Carbon Cycle
  • Burning fossil fuels for energy
  • Residential
  • Commercial
  • Industrial
  • Transportation
  • Clearing forests for agriculture forest
    products
  • Covering land with pavement
  • Exponential population growth

42
Effects of Higher CO2 Levels on Photosynthesis
  • Increased CO2 in the troposphere can increase
    plant photosynthesis (PS) but
  • The increase in PS would slow as the plants reach
    maturity.
  • Carbon stored by the plants would be returned to
    the atmosphere as CO2 when the plants die decay
  • Increased PS decreases the amount of carbon
    stored in the soil.

43
FACTORS AFFECTING THE EARTHS TEMPERATURE
  • Aerosol and soot pollutants produced by human
    activities can warm (SO4 aerosols) or cool (soot
    particulates) the atmosphere, but such effects
    will decrease with any decline in outdoor air
    pollution.
  • Warmer air can release methane gas stored in
    bogs, wetlands, and melting tundra soils and
    accelerate global warming (feedback?).

44
EFFECTS OF GLOBAL WARMING
  • A warmer climate would have beneficial and
    harmful effects but poor nations in the tropics
    would suffer the most.
  • Some of the worlds floating ice and land-based
    glaciers are slowly melting and are helping warm
    the troposphere by reflecting less sunlight
    (albedo) back into space (feedback?).

45
Fig. 19-5a, p. 501
46
Fig. 19-5b, p. 501
47
Sept. 1979
Sept. 2007
Russia
Russia
North pole
North pole
Greenland
Greenland
Alaska (U.S.)
Alaska (U.S.)
Canada
Canada
Fig. 19-6, p. 501
48
Rising Sea Levels
  • During this century rising seas levels are
    projected to flood low-lying urban areas, coastal
    estuaries, wetlands, coral reefs, and barrier
    islands and beaches (effects?)

Next
49

High Projection New Orleans, Shanghai, and other
low-lying cities largely underwater
35 inches
Mean Sea-Level Rises (centimeters)
Medium Projection More than a third of U.S.
wetlands underwater
4 inches
Low Projection
Year
IPCC (2000) Projections very likely (90-99
confidence level)
Fig. 20-10, p. 475
50
Rising Sea Levels
  • Changes in average sea level over the past
    250,000 years based on data from ocean cores.

Figure 20-9
51
Rising Sea Levels
  • If seas levels rise by 9-88cm during this
    century, most of the Maldives islands and their
    coral reefs will be flooded.

Figure 20-11
52

Warm, shallow current
Cold, salty, deep current
Fig. 20-12, p. 476
53
Changing Ocean Currents
It has recently been shown that the potential
shifting of ocean currents is less of a threat
than we thought before.
  • Global warming could alter ocean currents and
    cause both excessive warming and severe cooling.

Next
54
EFFECTS OF GLOBAL WARMING
  • Oceans remove 25-30 of tropospheric CO2
  • A warmer troposphere can decrease the ability of
    the ocean to remove and store CO2 by
  • decreasing the nutrient supply for calcareous
    phytoplankton that store CO2 in their calcium
    carbonate (CaCO3) shells, by potentially
    disrupting wind and ocean currents that provide
    nutrients via upwelling (feedback?)

55
EFFECTS OF GLOBAL WARMING
  • Increasing the acidity of ocean water
  • CO2 is dissolved in the ocean as carbonic acid,
    H2CO3
  • increased acidity interferes with calcareous
    phytoplankton shell formation
  • Increased acidity dissolves existing deposits of
    CaCO3 (feedback?)
  • CO2 is less soluble in warmer water (feedback?)

56
EFFECTS OF GLOBAL WARMING
  • Global warming will lead to prolonged heat waves
    and droughts in some areas (Africa, Asia,
    Western USA) and prolonged heavy rains and
    increased flooding in other areas (Europe more
    intense hurricanes and typhoons).
  • Between 1979 2002, the area of Earths land
    experiencing severe drought increased between 15
    and 30

57
Effects on Biodiversity Winners and Losers
  • Possible effects of global warming on the
    geographic range of beech trees based on
    ecological evidence and computer models.

Next
58

Beech
Future range
Overlap
Present range
Fig. 20-13, p. 478
59
EFFECTS OF GLOBAL WARMING
  • In a warmer world, agricultural productivity may
    increase in some areas (Canada Russia) and
    decrease in others (Asia Africa).why?
  • Crop and fish production in some areas could be
    reduced by rising sea levels that would flood
    river deltas (why?).
  • Global warming will increase deaths from
  • Heat and disruption of food supply.
  • Spread of tropical diseases to temperate regions.
  • Increase the number of environmental refugees.

60
DEALING WITH GLOBAL WARMING
  • Climate change is such a difficult problem to
    deal with because
  • The problem is global.
  • The effects will last a long time.
  • The problem is a long-term political issue.
  • The harmful and beneficial impacts of climate
    change are not spread evenly.
  • Many actions that might reduce the threat are
    controversial because they can impact economies
    and lifestyles.

61
DEALING WITH GLOBAL WARMING
  • Two ways to deal with global warming
  • Mitigation that reduces greenhouse gas emissions.
  • Adaptation, where we recognize that some warming
    is unavoidable and devise strategies to reduce
    its harmful effects.

62

Adaptation Strategies
Develop crops that need less water
Waste less water
Connect wildlife reserves with corridors
Move people away from low-lying coastal areas
Stockpile 1- to 5-year supply of key foods
Move hazardous material storage tanks away from
coast
Prohibit new construction on low-lying coastal
areas or build houses on stilts
Expand existing wildlife reserves toward
poles (why?)
Fig. 20-17, p. 485
63

Solutions
Global Warming
Prevention
Cleanup
Cut fossil fuel use (especially coal)
Remove CO2 from smoke stack and vehicle emissions
Shift from coal to natural gas
Store (sequester) CO2 by planting trees
Improve energy efficiency
Sequester CO2 deep underground
Shift to renewable energy resources
Sequester CO2 in soil by using no-till
cultivation and taking cropland out of
production
Transfer energy efficiency and renewable energy
technologies to developing countries
Reduce deforestation
Sequester CO2 in the deep ocean
Use more sustainable agriculture and forestry
Repair leaky natural gas pipelines and facilities
Limit urban sprawl
Use animal feeds that reduce CH4 emissions by
belching cows
Reduce poverty
Slow population growth
Fig. 20-14, p. 481
64
Solutions Reducing the Threat
  • We can
  • improve energy efficiency
  • rely more on carbon-free renewable energy
    resources
  • find ways to keep much of the CO2 we produce out
    of the troposphere (Carbon Capture
    Sequestration a.k.a. CCS)

65
Removing and Storing CO2
  • Methods for removing CO2 from the atmosphere or
    from smokestacks and storing (sequestering) it.

Figure 20-15
66

Spent oil reservoir is used for Crop field
Coal power plant
Tanker delivers CO2 from plant to rig
Tree plantation
Oil rig
CO2 is pumped down from rig for deep ocean
disposal
Abandoned oil field
Crop field
Switchgrass
CO2 deposit CO2 is pumped down to reservoir
through abandoned oil field
Spent oil reservoir is used for CO2 deposit
CO2 pumping
CO2 deposit
Fig. 20-15, p. 482
67
Problems with CCS
  • Unproven technology
  • Promotes continued use of fossil fuels
  • Requires huge government subsidies that draw
    funds from other solutions
  • There can be no leaks for any reason

68
DEALING WITH GLOBAL WARMING
  • Governments can
  • tax greenhouse gas emissions and/or carbon-based
    energy use
  • increase subsidies and tax breaks for saving
    energy
  • decrease subsidies and tax breaks for fossil
    fuels.

69
DEALING WITH GLOBAL WARMING
  • A crash program to slow and adapt to climate
    change now is very likely to cost less than
    waiting and having to deal with its harmful
    effects later (see below).
  • An ounce of prevention is worth a pound of cure

70
WHAT IS BEING DONE TO REDUCE GREENHOUSE GAS
EMISSIONS?
  • Getting countries to agree on reducing their
    greenhouse emissions is difficult.
  • ButA 2006 poll showed that 83 of Americans want
    more leadership from federal government on
    dealing with global warming.

71
International Climate Negotiations The Kyoto
Protocol (1997)
  • Treaty on global warming which first phase went
    into effect January, 2005 with 189 countries
    participating.
  • It requires 38 participating developed countries
    to cut their emissions of CO2, CH4, and N2O to
    5.2 below their 1990 levels by 2012.
  • Developing countries were excluded.
  • The U.S. and Australia did not sign, but
    California (worlds 6th largest economy) and
    Maine are participating.
  • U.S. did not sign because developing countries
    such as China, India and Brazil were excluded.

72
Moving Beyond the Kyoto Protocol
  • Countries could work together to develop a new
    international approach to slowing global warming
    (much has changed since 1997)
  • The Kyoto Protocol will have little effect on
    future global warming without support and action
    by the U.S., China, and India.
  • December 7-18, 2009 Copenhagen Climate Change
    Conference

73
Actions by Some Countries, States, and Businesses
  • In 2005, the EU proposed a plan to reduce CO2
    levels by 1/3rd by 2020.
  • Global companies (BP, IBM, Toyota) have
    established targets to reduce their greenhouse
    emissions to 10-65 below 1990 levels by 2010.

74
Actions by Some Countries, States, and Businesses
  • California has adopted a goal of reducing its
    greenhouse gas emission to 1990 levels by 2020,
    and 80 below by 2050.
  • The US EPA refused Californias request to set
    tough new standards(!)

75
Actions by Some Countries, States, and Businesses
  • BP spent 20 million to lower its greenhouse gas
    emissions to 10 below 1990 levels.
  • Took 3 years, from 1998 to 2001
  • Saved 250 million

76

What Can You Do?
Reducing CO2 Emissions
Drive a fuel-efficient car, walk, bike,
carpool, and use mass transit
Use energy-efficient windows
Use energy-efficient appliances and lights
Heavily insulate your house and seal all drafts
Reduce garbage by recycling and reuse (why?)
Insulate your hot water heater
Use compact fluorescent bulbs
Plant trees to shade your house during summer
Set water heater no higher than 49C (120F)
Wash laundry in warm or cold water
Use low-flow shower head
Buy products from companies that are trying to
reduce their impact on climate
Demand that the government make climate
change an urgent priority
Fig. 20-16, p. 485
77
OZONE DEPLETION IN THE STRATOSPHERE
  • During four months of each year up to half of the
    ozone in the stratosphere over Antarctica and a
    smaller amount over the Arctic is depleted.

Figure 20-19
78
OZONE DEPLETION IN THE STRATOSPHERE
  • Less ozone in the stratosphere allows for more
    harmful UV radiation to reach the earths
    surface.
  • The ozone layer keeps about 95 of the suns
    harmful UV radiation from reaching the earths
    surface.
  • Chlorofluorocarbons (CFCs) have lowered the
    average concentrations of ozone in the
    stratosphere.
  • In 1988 CFCs were no longer manufactured, due to
    the Montreal Protocol

79
Ultraviolet light hits a chlorofluorocarbon (CFC)
molecule, such as CFCl3, breaking off a chlorine
atom and leaving CFCl2.
Once free, the chlorine atom is off to attack
another ozone molecule and begin the cycle again.
A free oxygen atom pulls the oxygen atom off
the chlorine monoxide molecule to form O2.
The chlorine atom attacks an ozone (O3) molecule,
pulling an oxygen atom off it and leaving an
oxygen molecule (O2).
The chlorine atom and the oxygen atom join to
form a chlorine monoxide molecule (ClO).
Stepped Art
Fig. 20-18, p. 486
80
OZONE DEPLETION IN THE STRATOSPHERE
  • Since 1976, in Antarctica, ozone levels have
    markedly decreased during October and November.

Figure 20-20
81
OZONE DEPLETION IN THE STRATOSPHERE
  • Ozone thinning caused by CFCs and other ozone
    depleting chemicals (ODCs).
  • Increased UV radiation reaching the earths
    surface from ozone depletion in the stratosphere
    is harmful to human health, crops, forests,
    animals, and materials such as plastic and paints.

82

Natural Capital Degradation
Effects of Ozone Depletion
Human Health
Worse sunburn
More eye cataracts
More skin cancers
Immune system suppression
Food and Forests
Reduced yields for some crops
Reduced seafood supplies from reduced
phytoplankton
Decreased forest productivity for UV-sensitive
tree species
Wildlife
Increased eye cataracts in some species
Decreased population of aquatic species
sensitive to UV radiation
Reduced population of surface phytoplankton
Disrupted aquatic food webs from reduced
phytoplankton
Air Pollution and Materials
Increased acid deposition
Increased photochemical smog
Degradation of outdoor paints and plastics
Fig. 20-21, p. 488
Global Warming
Accelerated warming because of decreased ocean
uptake of CO2 from atmosphere by phytoplankton
and CFCs acting as greenhouse gases
83

This long-wavelength (low-energy) form of UV
radiation causes aging of the skin, tanning, and
sometimes sunburn. It penetrates deeply and may
contribute to skin cancer.
This shorter-wavelength (high-energy) form of UV
radiation causes sunburn, premature aging, and
wrinkling. It is largely responsible for basal
and squamous cell carcinomas and plays a role in
malignant melanoma.
Ultraviolet A
Ultraviolet B
Thin layer of dead cells
Hair
Squamous cells
Epidermis
Basal layer
Sweat gland
Melanocyte cells
Dermis
Basalcell
Blood vessels
Squamous Cell Carcinoma
Melanoma
Basal Cell Carcinoma
Fig. 20-22, p. 489
84
PROTECTING THE OZONE LAYER
  • To reduce ozone depletion, we must stop producing
    all ozone-depleting chemicals.

Next
85

What Can You Do?
Reducing Exposure to UV Radiation
Stay out of the sun, especially between 10 A.M.
and 3 P.M.
Do not use tanning parlors or sunlamps.
When in the sun, wear protective clothing and
sun glasses that protect against UV-A and UV-B
radiation.
Be aware that overcast skies do not protect you.
Do not expose yourself to the sun if you are
taking antibiotics or birth control pills.
Use a sunscreen with a protection factor of 15
or 30 anytime you are in the sun if you have
light skin.
Examine your skin and scalp at least once a
month for moles or warts that change in size,
shape, or color or sores that keep oozing,
bleeding, and crusting over. If you observe any
of these signs, consult a doctor immediately.
Fig. 20-23, p. 490
86
Updates Online
  • The latest references for topics covered in this
    section can be found at the book companion
    website. Log in to the books e-resources page at
    www.thomsonedu.com to access InfoTrac articles.
  • InfoTrac Upset about offsets Emissions offsets.
    The Economist (US), August 5, 2006 v380 i8489
    p53US.
  • InfoTrac Geologist seeks answers in Valley's
    house-sized rocks. Anchorage Daily News, August
    2, 2006.
  • InfoTrac Capital Pollution Solution? Jeff
    Goodell. The New York Times Magazine, July 30,
    2006 p34(L).
  • Union of Concerned Scientists Human Fingerprints
  • Science Daily Deep-sea Sediments Could Safely
    Store Man-made Carbon Dioxide
  • Discovery Channel Global Warming

87
Video Kyoto Protocol
  • This video clip is available in CNN Today Videos
    for Environmental Science, 2004, Volume VII.
    Instructors, contact your local sales
    representative to order this volume, while
    supplies last.

88
Video Melting Glaciers
  • This video clip is available in CNN Today Videos
    for Environmental Science, 2004, Volume VII.
    Instructors, contact your local sales
    representative to order this volume, while
    supplies last.

89
Video Global Warming
  • This video clip is available in CNN Today Videos
    for Environmental Science, 2004, Volume VII.
    Instructors, contact your local sales
    representative to order this volume, while
    supplies last.
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