Transcript Introduction - San Jose State University

MET 112 Global Climate Change - Lecture 12
Climate Change: Connections
Eugene Cordero
San Jose State University
Outline
 Ozone Depletion
 Water - Film
 Perspectives
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MET 112 Global Climate Change
Why is the ozone layer important
 Ozone acts as the Earth’s protective shield
against the Sun’s harmful Ultraviolet radiation
(UV radiation).
 The natural development of the ozone layer
permitted life to evolve above water.

Without the ozone layer, life would not exist
on Earth!
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Ozone, the good and the bad
Ozone is often
confused:
Stratosphere
Altitude (km)
Good ozone:
Stratospheric ozone
The ozone layer
Bad ozone:
Tropospheric ozone
Smog
Troposphere
Note: ozone is also
greenhouse gas
ozone
amount
At what time of year would you expect
UV values to be the highest?
Winter
Spring
Summer
Fall
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Cities with high levels of air pollution
correspond to high levels of
1. Stratospheric ozone
2. Mesospheric ozone
3. Tropospheric ozone
100%
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Where are the highest concentrations of
ozone located?
In large cities
The stratosphere
The troposphere
Near volcanoes
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Ozone Depletion
Topics
 History of Ozone Depletion
 The Ozone Hole: what, where, why?
 Ozone into the future
Early concerns of ozone depletion
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History of Ozone Depletion
 Chlorofluorocarbons (CFCs) developed in 1940’s
and 50’s as:
– Refrigerants, propellants, fire retardants
 1970’s CFCs detected in upper atmosphere.
– Many of these have long atmospheric lifetimes:
–(10’s to 100’s of years)
– 1974 Rowland and Molina propose that CFC’s
can destroy ozone in the stratosphere.
– CFC contain chlorine (Cl)
– Chlorine can destroy ozone rapidly
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MET 112 Global Climate Change
Ozone Hole Recipe
Ingredients:
Science interpretation



Chlorine gas
Cold Temperatures (~-80C)

Instructions:



Allow cold temperatures to form Polar
Stratospheric Clouds (1-2 weeks).

Allow time for polar stratospheric clouds
to convert chlorine gas into ozone
destroying chemicals. (1 month)

Polar Stratospheric Clouds allow ozone
friendly chlorine to be transformed into
ozone destroying chlorine.
Ozone depletion then starts when sun
returns to Antarctica in the spring
Bake ingredients with sunlight.


Chlorine gas is abundant in atmosphere
due to CFC’s
Cold Temperatures (~-80C) only occur
over Antarctica during the cold winter.
Presto, a delicious ozone hole!
Ozone hole grows from late August
through till October.
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What is being done about ozone
depletion?
 Montreal Protocol ~ (1988) international agreement
to reduce ozone depleting chemicals
 Further amendments accelerated the phase out.
– Developed countries have switched to HCFC’s
(more ozone friendly!)
– Developing countries have until 2004/5 to phase
out CFC’s.
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Is the Montreal Protocol working?
Seems to be!!!
Recent observations indicate that chlorine is
beginning to decline in the atmosphere.
Kyoto protocol uses similar approach
Start off with small achievable steps
Further amendments accelerate reductions
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What are predictions for the future?
 Model simulations suggest:
– atmospheric chlorine will return to pre-80’s level
In next 50 years or so .
__________________
A slow ozone recovery should follow
decreasing chlorine concentrations!!!
– Uncertainties still remain:
Phase out of CFC’s
 ____________________
Influence of global warming
 ____________________
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What is the connection between ozone
depletion and global warming?
 No direct connection between these environmental
issues.
 However: Global warming may enhance
ozone depletion
 Global warming produces:
– Tropospheric warming &
– Stratospheric cooling
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MET 112 Global Climate Change
What is the connection between ozone
depletion and global warming?
 An increase in greenhouse gases traps more heat
and thus
– The stratosphere tends to cool (stratospheric
cooling)
 Therefore, if the stratosphere cools, then
 Ozone hole chemistry
– PSCs will likely increase
– So slightly more ozone depletion
 Global warming will delay recovery of ozone layer
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Over the last 100 years, global
tropospheric ozone levels have been
1. increasing
2. decreasing
3. nearly constant
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The chemical that triggers rapid ozone
loss associated with CFCs is
Carbon Dioxide
Nitrogen dioxide
Methane
Chlorine
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The Antarctic ozone hole develops
during
SH Spring
SH Summer
NH Spring
NH Summer
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Global ozone values are expected to
recover in the next
10 years
30 years
50 years
100 years
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Drinkable Water (Freshwater)
 Of all the water in the world, 97% is
sea water (salt)
 Freshwater occupies only 3% of the
Earth’s water
 Of the freshwater, 77% of freshwater
is locked up as ice.
 Water is the most important natural
resources in the world.
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Drinkable Water (Freshwater)
Today, over 1 billion people don’t
have access to safe drinking water
The predictions of climate change
suggest that access to fresh water will
be made more difficult
–Changes in location and quanitity of
precipitation
–Raising sea levels
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Economic interest
Water
"One of the world's great business
opportunities. It promises to be to the
21st century what oil was to the
20th."
- Fortune Magazine
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While watching the documentary, Thirst,
think about the how the predictions of
future climate change (including water
resources) will intersect with the interest
and impact of water privatization.
Final Exam question:
Write an essay relating how the
predictions of future climate change may
intersect with the issue of water
privatization.
Local/National Policies
What are local/national governments doing to
reduce GHG emissions?
1.
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6.
Metr112: Main points
Let’s come up with the three most important points (i.e
concepts or themes) covered in this course.
1.
2.
3.
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Summary
Over the last 100 years and especially over the last thirtyfive years, the Earth climate has experienced a
significant warming trend.
Current levels of greenhouse gases are higher than
anytime over the last 400,000 years and likely longer.
Science is confident that humans are responsible for a
majority of the warming observed over the last 50 years.
The Earth’s climate will continue to warm and this
warming will place significant stress on social systems
throughout the world.
Significant climate change mitigation is urgently needed
to reduce negative impacts.
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Your opinion…
Global warming is under way?
Strongly Agree
Agree
Neutral
Disagree
Strongly Disagree
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The US should sign the Kyoto Protocol
Strongly Agree
Agree
Neutral
Disagree
Strongly Disagree
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Government should act to reduce
greenhouse gas emissions even if it
means raising energy prices
Strongly Agree
Agree
Neutral
Disagree
Strongly Disagree
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If you were going to help mitigate global
warming, which change would you feel
most comfortable making.
1. Taking public
transport more
2. Paying more for
gasoline
3. Altering your food
choices
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Global warming will affect your life?
Strongly Agree
Agree
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Strongly Disagree
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I would vote for a law that raises gasoline
taxes by $0.05 per gallon to improve energy
efficiency
1. Yes
2. No
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I would vote for a law that raises gasoline
taxes by $0.25 per gallon to improve energy
efficiency
1. Yes
2. No
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I would vote for a law that raises gasoline
taxes by $1.00 per gallon to improve energy
efficiency
1. Yes
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To help mitigate the impacts of climate
change, I’m willing to reduce the number of
miles I drive and fly
Strongly Agree
Agree
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Disagree
Strongly Disagree
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To help mitigate the impacts of climate
change, I’m willing to change my diet
Strongly Agree
Agree
Neutral
Disagree
Strongly Disagree
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To help mitigate the impacts of climate change, I will
encourage my friends and family to reduce energy
use
Strongly Agree
Agree
Neutral
Disagree
Strongly Disagree
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To help mitigate the impacts of climate change, I feel
compelled to do whatever I can to reduce greenhouse
gas emissions
Strongly Agree
Agree
Neutral
Disagree
Strongly Disagree
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Local Action: Does It Make a
Difference?
“Never doubt that a small group of thoughtful,
committed citizens can change the world;
indeed it’s the only thing that ever has.
-- Margaret Mead.
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