Download Climate Control and Ozone Depletion Notes

Brodnax
Concept 19-1: The overwhelming scientific consensus is that the earth’s atmosphere is warming rapidly,
mostly because of human activities, and that this will lead to significant climate change during this century.
Atmospheric Gases
 Nitrogen – 78%
 Oxygen – 21%
 Others – 1%
Argon, CO2, Neon,
Helium, Krypton,
Hydrogen, Xenon
Nitrogen and Oxygen do not
absorb significant radiation
(heat), but some of the others do
The Greenhouse Gases
(the ones that get hot)
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Water Vapor- H2O
Carbon Dioxide- CO2
Ozone- O3
Methane- CH4
Nitrous Oxide- N2O
Chlorofluorocarbons- CFCs
Without the natural greenhouse
effect, the earth would be cold
and uninhabitable
Human Activities Emit Large
Quantities of Greenhouse Gases
Since the Industrial Revolution…

CO2, CH4, and N2O emissions are
higher

Main sources: agriculture,
deforestation, and burning of fossil
fuels
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There is a correlation of rising CO2
and CH4 levels with rising global
temperatures
Scientists use ice cores to study past
atmospheric conditions
Estimated changes in the average global temperature of the atmosphere
near the earth’s surface over different periods of time
The Big Melt
Conclusions of the 2007 IPPC Report:
In 2007, AL Gore shared the
Nobel Peace Prize with the IPCC
(Intergovernmental Panel on
Climate Change) for alerting the
world to the reality and dangers
of global warming and its effects
on the world’s climate.
Gore said, “…the Earth has a
fever. And the fever is rising…We
are what is wrong, and we must
make it right.”
 Between 1906-2005, the average global surface temperature
has risen about 0.74˚C. Most has taken place since 1980.
 Annual greenhouse gas emissions from human activities rose
70% between 1970-2005 and average CO2 levels are higher
than they have been in 800,000 years.
 Over the past 50 years, arctic temps have risen almost twice as
fast as average temps in the rest of world.
 Glaciers and floating sea ice are melting and shrinking at
increasing rates, rainfall patterns are changing, and extreme
and prolonged drought is increasing.
 During the last century, the world’s average sea level rose by
10-20 cm, mostly from runoff from melting ice and warm-water
expansion
Sea Levels are rising

Expansion of warm water

Melting of land-based ice

What about Greenland?
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Areas of glacial ice melting in Greenland
during summer increased dramatically
between 1982 and 2007. If this net
melting of Greenland’s land-based ice
continues over a number of decades, the
world’s average sea level will rise sharply.
Areas of Florida will flood if average sea levels
rise by only 1 meter
GREENLAND
Atlantic Ocean
Global Warming could have severe
consequences
Worst-case scenarios:
 Ecosystems collapsing
 Low-lying cities flooded
 Wildfires in forests
 Prolonged droughts: grasslands become dust
bowls
 More destructive storms
 Glaciers shrinking; rivers drying up
 Premature extinction of many species
 Shifting in areas where crops can be grown
 Deaths from heat waves will increase
 Increase in air pollution, more O3
 More insects, microbes, toxic molds and fungi
Governments can enter into
International Climate Negotiations
Climate stabilization wedges:
15 ways to cut CO2 emissions
The Kyoto Protocol (1997 International Treaty)
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Goal- to reduce emissions of CO2, CH4, and N2O
by 2012 to levels of 1990
Trading greenhouse gas emissions among
countries
Not signed by the U.S.
• President G.W. Bush’s reasons
• It would hurt the economy
• Did not require reductions in China,
India, Brazil or Indonesia
• However, a majority of Americans
feel we should have signed
In 2005, countries began negotiating the second
phase that is supposed to go into effect after
2012.
Australia signed up for the second phase of the
Kyoto Protocol that would require reducing
greenhouse gas emissions to 5% below year 2000
levels by 2020.
Ways to prepare for the possible
long-term harmful effects of
climate change
 Develop crops that need less water
 Waste less water
 Move people away from low-lying
coastal regions
 Prohibit new construction on low-lying
coastal areas or build houses on stilts
 Stockpile 1-5 year supply of staple foods
 Move hazardous material storage tanks
away from coast
 Expand existing wildlife reserves toward
poles
Concept 19-4: Widespread use of certain chemicals has reduced ozone levels in the stratosphere,
which allows for more harmful ultraviolet radiation to reach the earth’s surface.
Ozone Thinning
A layer of ozone in the lower stratosphere keeps
about 95% of the sun’s harmful ultraviolet (UV-A and
UV-B) radiation from reaching earth’s surface.
Measurements reveal thinning of the ozone
everywhere except for the tropics with the most loss
over Antarctica and the Arctic.
The depletion varies with altitude, location and
o
season.
When the seasonal thinning ends each year, huge
masses of ozone-depleted air above Antarctica flow
northward, where it lingers over Australia, New
Zealand, South America and South Africa.
This raises biologically-damaging UV-B levels in
o
these areas by 3-10% and in some years as
much as 20%.
Arctic’s ozone-depleted air which flows south
to Europe, North America, and Asia.
Ozone-Destroying Chemicals
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CFCs: A Closer Look
Less severe ozone thinning happens with the
o
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Chlorofluorocarbons: CFCs (Freon’s)
•
Chemically unreactive, odorless, nonflammable,
nontoxic, noncorrosive compounds that were used in
refrigerants (AC/fridge) and as propellants in aerosol
cans

Halons & Hydrobromoflurocarbons (HBFCs) – fire
extinguishers
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Methyl Bromide (fumigant)
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Hydrogen Chloride (space shuttle)

Cleaning solvents: carbon tetrachloride, etc…
How CFCs affect Ozone
Equivalent Effective Stratospheric Chlorine
(EESC), a measure of atmospheric CFCs
•
•
CFCs are persistent in the
atmosphere
Rise into the stratosphere over 1120 years
Break down under high-energy UV
radiation
• Halogens produced
accelerate the breakdown of
O3 to O2
Each CFC molecule can last 65-385
years
1988: DuPont stopped producing
CFCs
Relationship between UV and Skin Cancer
We can REVERSE Stratospheric
Ozone Depletion
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Stop producing all ozone-depleting
chemicals
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60–100 years of recovery of the O3
layer
Adhere to the international treaties
that ban such chemicals:

1987: Montreal Protocol- cut CFC
emissions by 35% by year 2000
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1992: Copenhagen Protocolaccelerated the phase-out of ozonedepleting chemicals
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Ozone protocols: prevention is the
key