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The Atmosphere climate, climate change, and ozone depletion

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climate, climate change, and ozone depletion ... DEPLETION OF THE OZONE LAYER Lesson 20.5 Ozone Layer Protects Earth from harmful ultraviolet radiation. – PowerPoint PPT presentation

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Title: The Atmosphere climate, climate change, and ozone depletion


1
The Atmosphere climate, climate change, and ozone
depletion
  • Chapter 20

2
Hurricane Katrina
  • August 29,2005 made landfall in the Gulf Coast
    east of New Orleans.
  • Day before was a category 5, by landfall was a
    category 4 (131-155 mph winds).
  • Costliest storm ever 80 billion in damage.
  • 1300 deaths in four states.
  • 1 of 27 named storms that year.

3
The cycle of storms
  • 2005 part of a multi-decade cycle of ideal
    conditions for spawning hurricanes.
  • Abnormally warm surface temps.
  • Low wind shear.
  • Studies suggest there is a link between global
    warming and hurricanes.
  • Links atmosphere, oceans, human activities, and
    hurricanes.

4
Atmosphere and weather
  • Lesson 20.1

5
The Troposphere
  • Area closest to Earth
  • Where weather occurs.
  • Moderates the flow of energy to Earth
  • Involved in the biogeochemical cycling of many
    elements and compounds.
  • Capped by the tropopause.

6
The Stratosphere
  • Above the tropopause
  • Temperatures increase with altitude
  • Little vertical mixing of air and no
    precipitation from it
  • Substances can remain there (trapped) for a long
    time.
  • Location of ozone layer
  • Capped by the stratopause

7
Gases of the Atmosphere
  • Most crucial gases
  • Oxygen
  • Nitrogen
  • Carbon
  • Sulfur
  • Water

8
Weather vs. Climate
  • Weather
  • Climate
  • Day-to-day variations in temperature, air
    pressure, wind, humidity, and precipitation.
  • Mediated by the atmosphere.
  • Result of long-term weather conditions.
  • The study of both weather and climate
    (atmosphere) is called meteorology.

9
Air currents
  • Vertical
  • Horizontal
  • As heat is radiated back toward the atmosphere
    the gases near the Earth become heated, expanding
    and rising.
  • Air that must flow in to replace the rising air
    causes horizontal airflow (wind).
  • Convection currents bring us the day to day
    changes in our weather as they move in a general
    pattern from west to east.
  • Rising air creates high pressure area in
    atmosphere and low pressure on Earth.
  • Winds tend to flow from high to low pressure
    regions.

10
Hadley Cell
  • The ultimate source of the horizontal flow is
    cooler air that is sinking and the recombination
    produces the Hadley cell.

11
Jet Streams
  • Earths rotation and air-pressure gradients
    generate rivers of air.

12
Fronts
  • Air masses of different temperatures and
    pressures meet at boundaries called fronts.

13
CLIMATE
  • Lesson 20.2

14
Climate and biomes
  • The different temperatures and moistures in
    different parts of the world create the different
    ecosystems (biomes).
  • Tundra
  • Desert
  • Rainforest
  • These reflect the different adaptations of
    plants, animals, and microbes that will be
    present.

15
Humans and climate
  • Humans can adjust to practically any climate
    (short of the brutal conditions of mountain tops
    or burning deserts)
  • Other organisms in a region are adapted to a
    particular climate and any major changes present
    a major threat to the structure and function of
    the existing ecosystem.

16
Since 1880
  • Global average temperature has shown periods of
    cooling and warming, but the general pattern has
    increased 0.8C (1.4 F)

17
Warming trends
  • There have been two warming trends in the 20th
    century.
  • 1910-1945
  • 1976-present

18
Proxies
  • Measurable records that can provide data on
    factors such as temperature, ice cover, and
    precipitation.
  • Additional proxies include
  • Tree rings
  • Pollen deposits
  • Changes in landscape
  • Marine sediments
  • Corals
  • Ice cores

19
Why warming then ice ages?
  • The most likely explanation for the major
    oscillations is the existence of known variations
    in Earths orbit.
  • Orbital configuration varies the amount of solar
    radiation over different continents and latitudes
    substantially.
  • These intervals take place according to several
    periodic time intervals called Milankovitch
    cycles.
  • 100,000 years, 41,000 yrs. And 23,000 yrs.

20
Younger Dryas
  • Within the major oscillations of Milankovitch
    cycles are rapid climate fluctuations called
    Younger Dryas.
  • 10,700 years ago the temperature in the arctic
    region rose 7C in 50 years!
  • Tremendous effect on living organisms

21
El Nino
  • Occurs when a major shift in the atmospheric
    pressure over the Central Equatorial Pacific
    Ocean leads to a reversal of the trade winds that
    normally blow from an easterly direction.
  • Warm water spreads to the east, the jet stream
    strengthen and shift from their normal courses,
    patterns in precipitation and evaporation are
    affected.
  • Most severe El Nino occurred 1997-2000.
  • 1998 shifted to a La Nina.
  • Global damage approx. 36 billion, 22,000 deaths.

22
La Nina
  • Reverse of El Nino
  • Easterly trade winds are reestablished with even
    greater intensity, upwelling of colder ocean
    water in the eastern Pacific from the depths
    replaces surface water blown westward, the jet
    streams are weakened, and weather patterns are
    again affected.

23
Thermohaline
  • Refers to the effects that temperature and
    salinity have on the density of water.
  • Conveyer like system
  • Salty water from the Gulf stream is carried
    northward on the surface and is cooled by the
    arctic air currents. Cooling increases density
    of the water, which then sinks to depths of
    4,000m (the North Atlantic Deep Water NADW).
    This deep water spreads southward where it is
    joined by the northward Antarctic waters.

24
Thermohaline
25
Thermohaline
  • When the conveyer is interrupted, climate changes
    abruptly.
  • North Atlantic marine sediments show evidence of
    the periodic invasion of icebergs from the polar
    ice cap that supplied huge amounts of fresh water
    as they melted-called Heinrich events.

26
Global Climate change
  • Lesson 20.3

27
Factors affecting climate
  • Internal
  • External
  • Oceans
  • Atmosphere
  • Snow cover
  • Sea ice
  • Solar radiation
  • Earths rotation
  • Slow changes in orbit
  • Gaseous makeup of the atmosphere

28
Greenhouse Effect
  • The interior of a car heats up when the car is
    sitting in the Sun with the windows closed.
    Sunlight comes through the windows and is
    absorbed by the seats and other interior objects
    thus converting light energy to heat energy in
    the form of Infrared radiation. IR is trapped
    by the glass and cannot leave the car, causing
    the internal temperature to rise.
  • Earths glass is the CO2, water vapor, and
    other gases in the atmosphere.

29
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30
Greenhouse gases
  • Greenhouse effect was first recognized by
    Jean-Baptiste Fourier in 1827.
  • Without greenhouse gases the Earth would be too
    cold to inhabit.
  • Ozone in the troposphere has a positive forcing
    effect (leads to warming).
  • Negative forcing leads to a cooling effect.

31
IPCC
  • Intergovernmental Panel on Climate Change.
  • 1988, Established by the UN Environment Program
    and World Meteorological Society.
  • Established three working groups
  • One to assess scientific issues (working group I)
  • One to evaluate the impact of global climate
    change and the prospects for adapting to it
    (working group II)
  • A third to investigate ways of mitigating the
    effects (working group III)
  • Groups consist of more than 2000 experts in
    appropriate fields from over 100 countries.
  • The work of the IPCC has been guided by 2 basic
    questions
  • Risk assessment Is the climate changing and
    what is the impact on society and ecosystems?
  • Risk management How can we manage the system
    through adaptation and mitigation?

32
IPCC findings
  • January 2001 third assessment released
  • Bullets on pages 517-518
  • February 2007 fourth assessment released by group
    I
  • Global climate change is now occurring, it is an
    outcome of the rising levels of anthropogenic
    greenhouse gases, and the global impacts of the
    expected future changes will be unprecedented and
    severe

33
Carbon Sinks
  • Areas that absorb CO2 and keep it from
    accumulating at a more rapid rate in the
    atmosphere.
  • Oceans (uptake of CO2 by phytoplankton)
  • Terrestrial biota
  • See figure 20-11 on page 520

34
The greenhouse gases
  • Most abundant
  • Water vapor
  • Concentration in the atmosphere is quite variable
  • Rapid turnover in the lower atmosphere
  • Does not accumulate over time (unlike the other
    gases)
  • Other greenhouse gases
  • Methane (CH4)
  • Nitrous oxide (N2O)
  • Chlorofluorocarbons

35
ACIA
  • Arctic Climate Impact Assessment
  • 300 scientists and elders from six indigenous
    communities, funded by the National Science
    Foundation and the National Oceanic and
    Atmospheric Administration
  • Published in November 2004
  • Key findings (bullets pages 528-529)

36
Response to Climate change
  • Lesson 20.4

37
Responses to climate change
  • Adaptation we must anticipate some harm to
    natural and human systems and should plan
    adaptive responses to lesson the vulnerability.
  • Mitigation take action to reduce emissions
  • Skeptics base their arguments on the fact that we
    dont know much about the role of oceans, clouds,
    biota, and the chemistry of the atmosphere.

38
FCCC
  • Framework Convention on Climate Change
  • Document signed by the heads of state at the
    UNCED Earth Summit in Rio de Janeiro in 1992
  • Agreed to goal of stabilizing greenhouse gases in
    the atmosphere starting by reducing greenhouse
    gas emissions to 1990 levels by 2000.

39
FCCC
  • Proposed three principle
  • Precautionary principle though we may not know
    for sure, we must take action just in case.
  • Polluter pays principle polluters should pay for
    the damage their pollution causes.
  • Equity principle The richest produce the most
    CO2 and therefore should be the ones taking the
    action for the consequences paid by all.

40
Kyoto Protocol
  • Third conference of parties to the FCCC met in
    Kyoto, Japan in December 1997 to create an
    agreement on reducing greenhouse gases
  • 38 nations agreed to reduce emissions of 6 GHGs
    to 5 below 1990 levels by 2012.
  • Signers have a lot of flexibility on deciding how
    to meet the goals.
  • Kyoto expires in 2012

41
UN climate Control Conference
  • Agreed on two things
  • There will be future meetings to produce new,
    tougher set of binding limits on GHGs that will
    take effect after 2012.
  • Broader dialogue towards reaching nonbinding
    accords addressing global climate change.
  • George W. Bush opposes Kyoto for two reasons
  • It exempts the developing countries (unfair)
  • Cause serious harm to US economy

42
GCCI
  • February 2002
  • Global Climate Change Initiative
  • Reduction of 18 in emissions intensity (ratio of
    GHG emissions to economic output) over the next
    10 years

43
CCSP
  • July 2003, Bush administration report
  • Climate Change Science Program
  • Put sharper image on the governments approach to
    climate research.
  • Seeks to address a number of issues in climate
    science, such as the natural variability in
    climate

44
NCCTI
  • National Climate Change Technology Initiative
  • Provides support for research and analysis of
    GHGs and technologies to lower GHG emissions.

45
Likely consequences
  • Crop yields are likely to be reduced in tropical
    and subtropical areas
  • Water is likely to become more scarce in many
    regions already suffering
  • Increased heat and moisture in many regions
    leading to increased infectious disease and
    potentially lethal heat waves
  • Increased intensity and frequency of storm events
    (flooding)

46
Depletion of the Ozone Layer
  • Lesson 20.5

47
Ozone Layer
  • Protects Earth from harmful ultraviolet
    radiation.
  • Depletion mainly caused by human technologies,
    specifically the CFCs
  • Read table 20-5 on page 534.
  • Because the ozone layer blocks out more than 99
    of the UV radiation it is commonly referred to as
    the Ozone Shield.

48
Formation of Ozone
  • Formed in the stratosphere when UV radiation acts
    on oxygen molecules. The high-energy UV
    radiation first causes some molecular oxygen (O2)
    to split apart into free oxygen (O) atoms and
    these then combine with molecular oxygen to form
    ozone (O3)

49
CFCs
  • A type of halogenated hydrocarbon
  • Nonreactive, nonflammable, nontoxic organic
    molecules in which both chlorine and fluorine
    atoms have replaced some hydrogen atoms.
  • Under modest pressure, they liquefy giving off
    heat in the process and becoming cold.
  • Used as refrigerants, production of plastic
    foams, electronic industry for cleaning computer
    parts and as the pressurizing agent in aerosol
    cans.

50
CFCs Safe?
  • CFCs would be stable in the troposphere, but in
    the stratosphere they would be subject to intense
    UV radiation, which would break them apart,
    releasing free chlorine atoms via
  • CFCl2 UV ? Cl CFCl2
  • Chlorine acts as a catalyst to the break down of
    ozone.

51
Ozone hole
  • Fall 1985, British scientists working in
    Antarctica reported a hole in the stratospheric
    ozone layer.
  • The hole was actually a serious thinning.
  • Area the size of the US where ozone levels are
    less than 50 (of normal)
  • The hole was not discovered earlier by NASA
    because the computers were set to reject data
    showing a drop larger than 30.

52
Polar Vortex
  • Winter in the Antarctic (June).
  • A whirlpool like vortex which confines
    stratospheric gases within a ring of circulation
    air.
  • The cloud of particles provide surfaces on which
    chemical reactions release molecular Chlorine.
  • When summer arrives, the suns warmth breaks up
    clouds and UV radiation attacks the molecular
    Chlorine initiating the Chlorine cycle which
    rapidly destroys ozone.

53
Arctic Hole??
  • NO
  • Higher temperatures
  • Weaker vortex
  • Ozone depletion has occurred, but only at 25
    loss in especially cold winters.

54
Ozone depletion
  • Worldwide network on ozone measuring stations
  • Data sent to the World Ozone Data Center in
    Toronto, Canada
  • Depletion levels of 3 and 6 over the period
    2002-2005 in midlatitudes of the Northern and
    Southern hemispheres respectively.

55
Montreal Protocol
  • 1987, UN convened in Montreal Canada
  • Goal address ozone depletion
  • Members reached an agreement called the Montreal
    Protocol
  • Scale CFC production back 50 by 2000.
  • To date 184 countries (including the US) have
    signed
  • Because Ozone losses were greater than expected,
    an amendment was adopted in June 1990.
  • Phase out major CFC chemicals by 2000 (developed
    and 2010 (developing)
  • Another amendment November 1992
  • Complete CFC phaseout by January 1, 1996
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