Transcript pol1012bmod2b828229_2.pps

Tragedy of the Commons
• Commons
• resources that are shared or collectively owned
• Tragedy of the Commons
• a situation in which multiple individuals, acting independently,
and solely and rationally consulting their own self-interest, will
ultimately deplete a shared limited resource even when it is clear
that it is not in anyone's long-term interest for this to happen.
• Read this brief essay by Garrett Hardin
• Think about how the atmosphere is a commons and air pollution,
global warming,… represent tragedies of the commons.
• Discuss in the Forum
• Now we will look in-depth at one global issue dealing
with the atmosphere: Global Warming
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Global Warming
Video: Climate Change 101 with Bill Nye the Science Guy
• What’s heating the
Earth?
• Starts with solar
radiation
• Atmosphere lets
most light in
• Some reflected,
some absorbed
by ground
The Greenhouse Effect
Step 1: Earth’s surface
absorbs shortwavelength solar
radiation (visible light),
and becomes warmer
Step 2: Earth’s surface reradiates the energy as
long-wavelength
radiation (heat)
The Greenhouse Effect
(continued)
Step 3: Molecules of certain gases
in the atmosphere absorb some
of the heat, and the
atmosphere becomes warmer.
• Greenhouse gases (GHG): CO2,
water, methane, others
Greenhouse Effect, CO2,
and Global Warming
• The Greenhouse Effect
• Natural phenomenon that keeps us comfortable on Earth.
• CO2 is the most important greenhouse gas
• If less CO2 in atmosphere then temperature and climate are cooler
• If more CO2 in atmosphere then temperature and climate are
warmer
• Atmospheric CO2 levels today are about 393 parts per million (ppm)
or 0.0393%
• This may not seem like a lot, but it’s the highest in AT LEAST 800,000
years!
• Check out these two articles
• Ice Core Data Show Current CO2 Levels Highest in 800,000 Years
• UCLA Researchers Find CO2 at Highest Levels in 15 Million Years
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How Do We Know What
Prehistoric CO2 Levels Were?
• We examine ice core samples
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Ice Core Analysis
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Ice Core Analysis (continued)
• Most ice in glaciers and at the poles originates from snowfall
• Seasonal variation in snowfall causes layering in the ice
This image clearly shows
the annual layers in a
core sample
• The deeper we drill, the older the ice we extract
• Since the ice originated as snow, bubbles of air are trapped
inside
• The air bubbles are samples of the atmosphere from 1000s of
years ago
• By analyzing the chemical composition of the ice and air
samples, we can determine the approximate temperature and
the amount of CO2 present in the atmosphere
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Ice Core Analysis (continued)
• Examine the Vostok ice core graph on the previous page
• It covers a 400,000 year period ending in 1950 CE (AD)
• What is the apparent relationship between atmospheric CO2 and
temperature?
• From previous slides, what is the atmospheric CO2 level in 2010?
• What could that mean for global temperatures?
• Ice core data from the North and South Poles as well as data
from near the equator in Hawai’i show rapid rise in
atmospheric CO2
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Where does CO2 come from?
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CO2 and Human Activity
This box is a zoomed in
view of the past 1000 years
It suggests that human
activity has caused the
dramatic increase in CO2
levels
Causes: burning of fossil
fuels, wood,…; destruction
of “carbon sinks” (ex: trees
and algae that absorb
carbon)
The graph on the next slide
shows an even stronger
correlation between people
and CO2
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Human
Activity
and CO2
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Evidence the Earth is Warming
January Mean Daily Temperatures at Anchorage, Alaska
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Mean Daily Temp (deg C)
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1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
Year
Daily Mean
5 per. Mov. Avg. (Daily Mean)
Linear (Daily Mean)
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What about Ohio?
(Data from US Historical Climatology Network)
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What about other stations?
Pacific Coast
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Pacific Northwest
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Desert Southwest
(Note this is maximum not mean)
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Rocky Mountains
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Central Great Plains
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Southeast
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Northeast
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With respect to average temperature 1940-1980
Global average temperature
1855-2002
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Look at the colored bars representing average
temperature changes per decade over the past 150
years. Note how the rate of temperature increase is
increasing. I.e., we’re getting warmer faster.
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Some of the Effects of Global
Warming
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Snow Cover on
Mt. Kilimanjaro,
Tanzania
1993 and 2000
Check out this brief video for more
on Kilimanjaro’s glaciers.
National Geographic on Kilimanjaro
Think about it:
1.
2.
3.
4.
What is occurring on Kilimanjaro?
Where else in the world do you
think this is happening?
How important is it?
What will be the impact on humans,
wildlife, agriculture,…?
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Arctic Sea Ice Coverage, 1979-2007
Note the rapid
decrease in sea ice
coverage. As global
warming causes
reductions in sea ice,
the lack of sea ice
causes further global
warming. This is
because ice is more
reflective than open
ocean. It reflects
sunlight and heat
back into space. As it
vanishes, more
sunlight is absorbed
by the seas and the
warmer they become.
The warmer the seas,
the more ice melts…
Rising Oceans
• Sea ice melt does
not affect sea level
since the ice that
melts was already
displacing water
• However, melt
runoff from
glaciers and ice
cover on land
(Antarctica,
Greenland,…) does
cause sea level
rise
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Additional Effects
• Loss of habitat and extinction of species
• Extreme weather events
• Changes in precipitation patterns
• Shifts in agricultural zones
• Expansion of tropical disease ranges
• Flooding of low-lying areas
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Climate Change Regime
• Inter-governmental Panel on Climate Change (IPCC)
• Leading UN agency that researches and advises on climate change
• National Oceanic and Atmospheric Administration (NOAA)
• Key US agency dealing with climate change
• Kyoto Protocol, 1997
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Legally binding targets for greenhouse gas (GHG) reductions
Went into effect in 2005
Some see it as a crucial step toward controlling GHG
Others see it as a failure. USA signed but never ratified Kyoto
• Copenhagen Accord, 2009
• New International agreement to reduce GHG
• Pros: all countries now recognize global warming as “one of the greatest
challenges of our time”
• Cons: very weak , not legally-binding, strong disagreements between MDCs
and LDCs
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Just so you know where we
stand…
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Climate is changing. How can
we adapt?
• Watch this TED Talk by Vicki Arroyo
• 10 minute video:
• Let’s Prepare for Our New Climate
• Write a 4-5 paragraph summary & analysis
• Submit under Assignments on Isidore
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Other Atmospheric Issues—
Ozone Depletion
• Has NOTHING directly to do with global warming
• Certain chemicals (Ozone depleting substances—ODS) interact with
and destroy ozone (O3) in the stratosphere
• Common ODS: chlorofluorocarbon (CFC) from aerosol cans, refrigerators,
solvents, ... ; halon from fire extinguishers; nitrous oxide; and others
• Lower levels of stratospheric ozone allow in too much ultraviolet (UV)
radiation from the sun, which causes blindness, skin cancer, and,
potentially, eradication of all life on earth
• Montreal Protocol, 1987
• Agreement to halt the production of CFC.
• Most successful international agreement of ALL TIME
• Ozone layer is currently repairing itself
• As long as countries follow Montreal Protocol, the problem should be
fixed
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Other Atmospheric Issues—
Acid Rain
• A global issue because it is often transboundary (crosses
borders)
• Primarily from burning of high sulfur content coal in power
plants for electricity generation
• Sulfur dioxide (SO2) in power plant emissions combines with
water vapor (H2O) in the atmosphere to produce H2SO4—
Sulfuric Acid
• Adverse effects
• Soil and bodies of water become more acidic, killing microbes, insects,
fish, and plants
• Damages agriculture, ecosystems, forests, buildings, and has been
linked to some cancers and other diseases in humans
• No UN agreements on acid rain since, unlike global warming and ozone
depletion, it is not a global, but a regional problem
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Acronyms to Know
• Find them in the chapter,
power point, or the list of
acronyms on p.329 in the
text
• The acronyms of Modules
7 & 8 are combined for the
Acronym 5 Assignment
• Once you know what each
acronym stands for, go to
Assignments and complete
the Acronym 5 assignment
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CFC
CO2
GHG
IPCC
NOAA
ODS
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Assignments—Due 7/27
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News Summary and Analysis on Climate Change
Vicki Arroyo TED Talk essay
Acronym 5 Assignment
Module 8 Discussion in Forum
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