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Chapter 19
Global Change
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Global Change
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o
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Global change- any chemical, biological or physical
property change of the planet.
Global climate change- changes in the climate of the
Earth.
Global warming- the warming of the oceans, land
masses and atmosphere of the Earth.
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The Sun-Earth Heating System
The Greenhouse Effect
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2.
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Incoming solar energy = 100%
- Radiation is absorbed by the clouds and the surface
of Earth thus becoming warmer.
I/3 of all solar energy is reflected.
Most of the infrared radiation from Earth is absorbed by
greenhouse gases in the atmosphere.
- The rest is emitted back into space.
- Known as the greenhouse effect.
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Greenhouse Gases
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Water vapor
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Absorbs and
releases
energy
Carbon
dioxide
Methane
Nitrous oxide
Ozone
CFCs
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Greenhouse warming potential—ratio of how much a
molecule of a compound can contribute to global
warming over 100 years compared to 1 molecule of
CO2
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4 Natural Greenhouse Gases
1. Volcanic eruptions
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CO2—long term effects
Particulate Matter — (ash) shorter term
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Ash reflects incoming solar radiation back to
space, causes Earth’s temperature to decrease.
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4 Natural Greenhouse Gases
2. Methane – is created when there is not enough
oxygen available to produce carbon dioxide
during decomposition.
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Occurs at the bottom of wetlands – largest natural
source of methane (anaerobic decomposition)
Organism digestion, gut of a termite, no oxygen is
present methane given off. Second largest source.
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4 Natural Greenhouse Gases
3. Nitrous oxide
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Produced during denitrification
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NO3-  N2O
Occurs in a low oxygen environment such as soils at the
bottom of wetlands, lakes, and oceans.
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4 Natural Greenhouse Gases
4. Water vapor
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Most abundant
Greatest contributor
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5 Anthropogenic Sources of
Greenhouse Gases
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5 Anthropogenic Sources of
Greenhouse Gases
1. Burning of fossil fuels
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Trapped reserves of CO2 plants don’t take in as
much as we are contributing during burning.
Coal v. Petroleum v. Natural gas
Particulate Matter
“Black soot”
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5 Anthropogenic Sources of
Greenhouse Gases
2. Agricultural practices
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Anaerobic conditions (CH4 and N2O)
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Fertilizers
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Irrigation and flooding for cultivating crops create low
oxygen environments for bacteria.
Excess Nitrates are added denitrification = N2O
Livestock
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Digestion – sheep and cows rely on gut bacteria to
break down cellulose which produces a lot of CH4
Manure lagoons – not aerated, decompose and
release CH4
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5 Anthropogenic Sources of
Greenhouse Gases
3. Deforestation…without replacement
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Plants remove CO2
Slash-and-burn method (shifting agriculture)
releases CO2, CH4, and N2O
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5 Anthropogenic Sources of
Greenhouse Gases
4. Landfills
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Anaerobic methane generation from low oxygen
due to poor aeration.
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5 Anthropogenic Sources of
Greenhouse Gases
5. Industrial production
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CFCs replaced by HCFCs
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Increasing CO2 Concentrations
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David Keeling began measuring CO 2 in 1958.
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Emissions from the Developed
and Developing World
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Temperatures and Greenhouse Gas
Concentrations in Past 400,000 Years
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Indirect measurements—lack of records
o Changes in species compositions
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Foraminifera
Chemical analyses of ice
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Historic CO2 Concentrations
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Historic CO2 Concentrations
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Putting It Together
- 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.
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1. Global sea level rose about 17 centimeters (6.7 inches) in the last
century. The rate in the last decade, however, is nearly double
that of the last century.
2. Average Arctic temperatures increased at almost twice the
global average rate in the past 100 years. Shrinking glaciers and
ice caps.
3. Most of this warming has occurred since the 1970s, with the 20
warmest years having occurred since 1981 and with all 10 of the
warmest years occurring in the past 12 years.
4. Seasonal events starting earlier and ending later
5. The top 700 meters (about 2,300 feet) of ocean showing warming
of 0.302 degrees Fahrenheit since 1969
6. The number of record high temperature events in the United
States has been increasing, while the number of record low
temperature events has been decreasing, since 1950. The U.S.
has also witnessed increasing numbers of intense rainfall events.
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Feedbacks
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Feedbacks
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POSITIVE
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High C in soil
High temperatures
 decomposition
 CO2 in
atmosphere
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NEGATIVE
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High CO2
 plant growth

Removes CO2
Tundra warms
Anaerobic
decomposition
CH4
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Consequences to the Environment
From Global Warming
1. Melting of polar ice caps, Greenland and
Antarctica
2. Melting of many glaciers around the world
3. Melting of permafrost
4. Rising of sea levels due to the melting of glaciers
and ice sheets and as water warms it expands
5. Heat waves more frequent
6. Cold spells lessening
7. Change in precipitation patterns
8. Increase in storm intensity
9. Shift in ocean currents
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North Pole is currently 39% smaller than it was in 1979
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1. Thermal expansion
2. Additions of water from melting ice
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Consequences to Living
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
harmed 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.
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The Controversy of Climate
Change
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The fundamental basis of climate changethat greenhouse gas concentrations are
increasing and that this will lead to global
warming is not in dispute among the vast
majority of scientists.
What is unclear is how much world
temperatures will increase for a given
change in greenhouse gases, because
that depends on the different feedback
loops.
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The Kyoto Protocol
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1997, Japan--discuss how best to control
emissions contributing to global warming.
Green house gas emissions from all
industrialized countries will be reduced to
5.2% below their 1990 levels by 2012.
Developing nations did not have emission
limits imposed by the protocol.
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