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Chapter 19
Global Change
Global Change
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Global change- any chemical, biological or physical
property change of the planet. Examples include cold
temperatures causing ice ages.
Global climate change- changes in the climate average
temperature of the Earth.
Global warming- one aspect of climate change, the
warming of the oceans, land masses and atmosphere of
the Earth.
Greenhouse Gases Natural
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Water vapor
Volcanic
eruptions
Carbon dioxide
Methane
Nitrous oxide
Ozone-O3
simulation
Anthropogenic Causes of
Greenhouse Gases
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Burning of fossil fuels-NOx, SO4, CO, CO2
Agricultural practices-all the above & CH4
Deforestation-increases CO2 and CH4
Landfills-CH4
Industrial production- CFC’s
Chloroflourocarbons
Feedbacks
Increasing CO2 Concentrations
We reached
400ppm in 2014!
We reached
400.9ppm in
2015!
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Use the graph to
Determine the net
change in atmospheric
CO2 concentration
between 100,000 YA &
present day levels.
1. Read the graph to find the CO2levels for 100,000
years ago and for the present day.
100,000 years ago: CO2 levels were about 230 ppm
(An accepted range of answers would be 220ppm to
235ppm) Present day: CO2 levels are about 390 ppm
(An accepted range of answers would be 380ppm to
395ppm)
2. subtract the 100,000 years ago from present day
390 ppm – 230 ppm = 160 ppm increase of CO2
concentration over past 100,000 years
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Formation of ozone O2 + O =O3
1 CFC molecule breaks up 100,000 O3
molecules
If there were 200 CFC’s how many O3
molecules would be broken up?
Stratospheric Ozone
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The stratospheric ozone layer exists roughly 45-60
kilometers above the Earth.
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Ozone has the ability to absorb ultraviolet radiation
and protect life on Earth.
Formation and Breakdown of Ozone
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First, UV-C radiation breaks the bonds holding together the
oxygen molecule , leaving two free oxygen atoms:
O2 + UV-C -> O2
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Sometimes the free oxygen atoms result in ozone:
O2 + O -> O3
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Ozone is broken down into O2 and free oxygen atoms when it
absorbs both UV-C and UV-B ultraviolet light:
O3 + UV-B or UV-C -> O2 + O
Anthropogenic Contributions to
Ozone Destruction
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First, chlorine breaks ozone’s bonds and pulls off one atom of
oxygen, forming a chlorine monoxide molecule and O2: O3 +
Cl -> ClO + O2
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Next, a free oxygen atoms pulls the oxygen atom from ClO,
liberating the chlorine and creating one oxygen molecule:
ClO + O -> Cl + O2
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One chlorine atom can catalyze the breakdown of as many as
100,000 ozone molecules before it leaves the stratosphere.
How CFC break up O3
Polar Vortex
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CIRCULATING WINDS ISOLATE COLD AIR
traps WARM AIR inside the circulating vortex
When ambient AIR IS -80C CLOUDS form of
WATER & NITRIC ACID. This acidic vapor
allows CFC’S to breakdown into CHLORINE
SUNLIGHT returns in the SPRING so it
increases the rate of Ozone depletion
Polar Vortex
Anthropogenic Contributions to Ozone
Destruction
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Certain chemicals can break down ozone, particularly
chlorine.
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The major source of chlorine in the stratosphere is a
compound known as chlorofluorocarbons (CFCs)
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CFCs are used in refrigeration and air conditioning, as
propellants in aerosol cans and as “blowing agents” to inject
air into foam products like Styrofoam.
Anthropogenic Contributions to Ozone
Destruction
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When CFCs are released into the troposphere they
make their way to the stratosphere.
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The ultraviolet radiation present has enough energy
to break the bond connecting chlorine to the CFC
molecule.
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which can then break apart the ozone molecules.
Depletion of the Ozone Layer
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Global Ozone concentrations had decreased by more than 10%.
In the Antarctic it can be as much as 70%
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Depletion was greatest at the poles
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Decreased stratospheric ozone has increased the amount of UVB radiation that reaches the surface of Earth.
Emissions Developed V. Developing Look at
per/capita
Global Temperatures since 1880
Sea ice change Interactives NASA
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Since 1880 temperatures
have increased 0.8°C.
However, some have
declined.
Temperatures and Greenhouse Gas Concentrations in
Past 400,000 Years
Habitable Planet chapter 13 video first 16’
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No one was around thousands of years ago to measure
temperatures so we use other indirect measurements. Some of
these are
 Changes in species compositions
 Chemical analyses of ice
 Measurement of CO2 gas in ice cores
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Ocean sediments can tell what past ocean
temperature and CO2 levels were like
Video clip
Consequences to the Environment Because of Global Warming
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Melting of polar ice caps, Greenland and Antarctica
Melting of many glaciers around the world
Melting of permafrost
Rising of sea levels due to the melting of glaciers and
ice sheets and as water warms it expands
Heat waves
Cold spells
Change in precipitation patterns
Increase in storm intensity
Shift in ocean currents
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What is the ITCZ
Where does it take up a
larger area?
What are the effects of this
shift?
Consequences to Organisms
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Wild plants and animals can be affected. The
growing season for plants has changed and
animals have the potential to be
endangered/threatened if they can’t move to
better climates.
Humans may have to relocate, some diseases
like those carried by mosquitoes could increase
and there could be economic consequences.
The Controversy of Climate
Change
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The fundamental basis of climate change- that
greenhouse gas concentrations are increasing
and will lead to global warming is not in
dispute among 98% climate scientists
What is unclear is how much world
temperatures will increase for a given change
in greenhouse gases, depends on feedback
loops.
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Loss of moisture
Ground water recharge-drought, flooding
Salinization of soil-infiltrate of sea water
along coastal areas
Higher CO2 increases growth rate. Soil can
absorb it.
Increased soil temperature
Putting It Together
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We know that an increase in CO2 in the
atmosphere causes a greater capacity for
warming through the greenhouse effect.
When the Earth experiences higher
temperatures, the oceans warm and cannot
contain as much CO2 gas and, as a result, they
release CO2 into the atmosphere.
The Kyoto Protocol
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1997, nations went to Kyoto, Japan to discuss how best
to control the emissions contributing to global
warming.
agreement -emissions of greenhouse gases from all
industrialized countries will be reduced to 5.2% below
1990 levels by 2012.
The U.S. did NOT sign-Developing nations did not
have emission limits imposed by the protocol.
Update! U.N. Agreement COP21 (conference of parties,
21st meeting)
Key highlights
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Limit warming to 1.5 C above pre-industrial levels.
Reduce deforestation, encourage sustainable forestry
Developed countries collect funds to assist developing
countries
System to verify reductions by countries
Balance between anthropogenic output and sinks
Avert, minimize loss & damages by countries
Meet every 5 years with new reduction limits (used to
be 10 years)
Carbon Sequestration
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taking CO2 out of the atmosphere
include storing carbon in agricultural soils or
retiring agricultural land and allowing it to
become pasture or forest-return carbon sink
captured CO2 would be compressed and
pumped into abandoned oil wells or the deep
ocean.