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Global Warming and the Ozone Hole

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Global Warming and the Ozone Hole. The Greenhouse Effect ... 'Warming of the climate system is unequivocal, as is now evident from ... – PowerPoint PPT presentation

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Title: Global Warming and the Ozone Hole


1
Global Warming and the Ozone Hole
2
The Greenhouse Effect
  • A normal climatic warming effect caused by
    permitting incoming solar radiation but
    inhibiting outgoing terrestrial radiation.
  • Three gases are the primary cause
  • Carbon Dioxide (CO2)
  • Methane (CH4)
  • Water Vapor (H2O)
  • The effect is possible because outgoing earth
    radiation is of much longer wavelengths than
    incoming insolation and it gets caught or trapped
    in the atmosphere.

3
The Greenhouse Effect
  • Keeps Earths average temperature 35ºC warmer
    (15ºC now, -20 ºC otherwise)
  • Human role? A heated
    debate

Venus 480ºC thick carbon
dioxide
Mars -62 ºC little carbon dioxide
4
The Carbon Cycle
5
Global Surface Temperature Increase 1865-2000
6
Note that very recent rate of increase greatly
exceeds anything in last 1000 years.
7
b
8
Note correlations in the data.
9
Critics note that historic temperatures were
higher.
10
Critics note that historic temperatures were
higher.
11
650,000 years of climate and CO2
12
Changes in Solar Radiation
Milankovitch Cycles explain much (60) of the
changes
  • 21,000 year cycle perihelion shifts throughout
    the year
  • 41,000 year cycle /- 1.5 change in Earth's
    tilt
  • 100,000 year cycle Orbital eccentricity of the
    elliptical orbit of the Earth


The most recent ice age lasted 100, 000 years. We
are currently in an interglacial period
(Holocene).
13
Climate models suggest that the changes are just
beginning now and will accelerate.
14
The Global Warming Hypothesis
  • Human-induced rise in CO2 levels is likely to
    lead to increased greenhouse forcing and
    unnatural warming of atmosphere.
  • Some probable effects
  • Increased storminess and more droughts
  • Rising sea level (.36 to 2.5 feet) in 100 years
    (IPCC, 2007)
  • Loss of farmable land (some areas hotter, others
    cooler)
  • Extinction of thousands of species
  • Loss of nearly all coral reef
  • Increased range of tropical diseases
  • Flooding of low-lying coastal regions

15
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.
IPCC Report, 2007
16
So is sea level rise happening? How much?
Sea level rise is not well understood. In their
2001 report, the Intergovernmental Panel on
Climate Change stated that global warming should
cause sea levels to rise 0.11 to 0.77 meters
(0.36 to 2.5 feet) by 2100. When added to storm
surges and high tides, these small changes may
have large effects.
Source UN IPCC, 2001
Source UN IPCC, 2001
17
Global Warming?
  • Climate change will lead to more chaotic and
    unpredictable weather "Climate change will bring
    warm, wet weather, which will encourage plants to
    grow, followed by long periods of drought, during
    which they will burn." - Meinrat Andreae, Max
    Planck Institute for Chemistry, August 2001.

18
So is Global Warming Happening?
  • Scientific consensus now exists (link to
    Wikipedia)
  • "In the light of new evidence and taking into
    account the remaining uncertainties, most of the
    observed warming over the last 50 years is likely
    to have been due to the increase in greenhouse
    gas concentrations 1." (IPCC, 2001)
  • We must act to ensure continued economic growth
    for our citizens and for citizens throughout the
    world. - George W Bush, June 2001, Explaining
    his opposition to the 1997 Kyoto Protocol, a
    document that calls for only 5 reduction of
    greenhouse gases. IPCC says a 60 reduction
    needed to stabilize levels.

19
Predicted temperature changes Hadley Centre model
Source UKMO Hadley Center http//www.met-office.
gov.uk/research/hadleycentre/
20
Predicted precipitation changes Hadley Center
model
Source UKMO Hadley Center http//www.met-office.
gov.uk/research/hadleycentre/
21
Ecosystem change
  • Very difficult to model!
  • Response depends on CO2 fertilization,
    temperature, Precipitation, evapotranspiration,
    competition...

22
The Ozone Hole
23
The Vertical Thermal Structure of the Atmosphere
IONOSPHERE
OZONOSPHERE
24
  • Ozone forms naturally in stratosphere
  • UV radiation (sun) --gt mutations
  • plankton reduced (food chain base), crops decline
  • weaker immune systems, skin cancer
  • Stratospheric ozone (O3) absorbs UV rays

light
?
O2 ? 2 O then O O2 ? O3
UV rays
?
O3 ? O2 O
25
The Importance of Stratospheric Ozone
  • CFCs
  • link to ozone hole established in 1970s
  • Chloroflourocarbons (refrigerants, aerosols)
  • one Cl can decompose more than 100,000 O3

Cl2 light ---gt 2 Cl Cl O3 ---gt ClO O2 ClO
O Cl O2
26
NASA Ozone Watch Images Data Animations
27
The Importance of Stratospheric Ozone
  • What has been done?
  • Montreal Protocol, 1987 U.N. agreement on ban
  • up to 10 years for rising CFC gases to reach
    stratosphere once in the stratosphere, CFCs can
    last up to 50-100 years
  • Nasas Ozone Hole Site

28
Key Points
  • Ozone Hole caused by CFCs
  • Ozone protects life from UV rays
  • destroys ozone in stratosphere
  • has little effect on temperature
  • Montreal Protocol, 1987 outlawed production of
    CFCs
  • Global Warming caused by carbon dioxide and
    methane
  • Carbon dioxide traps heat radiated towards space
    by the earth
  • leads to warming at surface of earth
  • Will effect temperature, sea level, storm
    intensity, and ecosystems
  • No global agreement to solve problem
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