Physics 6 Schedule
April 12
Times Beach Video
April 14
Video Discussion
April 19
Alternative Energy
April 21
Global Warming
April 26
6 Student Talks
April 28
10 Student Talks
May 3
12 Student Talks
May 5
3 Student Talks
“Is the human race like the bucket of frogs about to be boiled, led and bossed by
happy frogs who don't know they're in the same bucket?”—culturechange.org
Your 35 Talks
April 26 (6)
Hilkemeyer
Huff
Jones
McFarland
Rohrer
Vandemark
Other (3)
Kipp, Dotson, Toscano
April 28 (9)
Brady
Fischer
Gavin-Ellison
Gregory
Harris
Jenkins
Kueck
Reeves
Venayagamoorthy
May 3 (11)
Bassett
Bukulmezer
Culen
Faison
Gorham
Gutierrez
Naito
Newman
Peaslee
Saunders
Thompson
May 5 (6)
Butler
Duvall
Haas
Lester
McConnell
Todd
Grading sheet:
environment-related topic (0-3)
scientific evidence presented (0-5)
effort by presenter to evaluate evidence (0-4)
talk organized and flowed logically (0-5)
evidence of thought on part of presenter (0-5)
good effort and enthusiasm (0-3)
total (0-25)
Onondaga Cave
Take exit 214 (Leasburg exit).
Go south on Route H for 7
miles.
Go through Leasburg to get
to Onondaga Cave State Park.
The paved road ends just before you get
to the visitor center.
28 miles from exit 186 to exit 214, 7 miles to park. Julia
says 35 minutes. Park web site says 45 minutes.
If you cross the Meramec
river, you’ve gone too far!
Global Warming
Sources of Information
Information is not really so neatly packaged as I will make it
sound here… but there seems to be 3 “types” of sources of
information on global warming.
Government agencies such DOE (Department of Energy), EPA,
NOAA, USGS, NASA.
They tend to emphasize facts and present information
(sometimes too much!). They will mention areas of speculation
without drawing conclusions.
Environmentalist organizations.
Web site examples:
http://globalwarming.enviroweb.org
Natural Resources Defense Council
You will find lots of valuable information on these sites.
You will also find lots speculative information expressed as if
it were fact.
Why are they expressing speculation as if it were fact?
Opinion: they believe their speculation represents the truth.
They know it takes a major emergency to wake up a
democratic society. They want to wake people up “before
it’s too late.”
Global warming skeptics.
Web site examples:
http://www.skepticism.net/faq/environment/global_warming/
www.globalwarming.org
Global warming skeptics, for a variety of reasons, don’t want
government involved in business or personal matters.
Unfortunately, this seems to have turned into a political debate
between conservatives and moderates.*
Debates about science settle nothing. A theory works or it
doesn’t. Nature doesn’t care** about your opinion. Nature
doesn’t care about how good you are at convincing other
people you are right.
What do you do if a theory is inconclusive? Discuss, argue,
experiment, revise your theory, experiment some more.
Debate is for the Debate Team.
*Opinion: there are no liberals left in this country. Well, not enough to be
worth counting.
**Of course, “nature,” being inanimate, doesn’t “care” about anything.
A personal note.
I am OK with you voicing your opinion.
I am OK if you disagree with me.
I am not OK if you want to force me to take action based on
your opinion alone.
I am very disturbed if you attempt to conceal your motives
behind a name.
I find it’s easy to tell when you’re dealing with an
“environmentalist.” The skeptics may let you know who they
are, but you may have to do a lot of digging.
www.globalwarming.org seems to be run by an organization
called the “National Consumer Coalition.” They believe in a free
market economy. Government has no business getting
involved.
The trouble is, I can’t tell if the “National Consumer Coalition”
is really a coalition of consumers.
Opinion: the skeptics tend argue by tearing down, focusing on
areas of disagreement and dispute and claiming these areas
are “proof” that global warming is not real, when in fact, they
are only proof that science is being done.
Watch for inflammatory uses of words. “Global warming
handwringers...” If you have to make a point by name calling,
I question whether you have a point.
I should give equal treatment to the environmentalists,
shouldn’t I?
“Now that we know of massive species extinction and a North
Atlantic ice age right up ahead, the question for any concerned
citizen: Is the human race like the bucket of frogs about to be
boiled, led and bossed by happy frogs who don't know they're
in the same bucket? We have met the enemy and he is
us. Stop the global warmers!” http://www.culturechange.org/
They’re even holding a “World Naked Bike
Ride Day” in June to protest! If you can’t
make a point with your clothes on, I question
whether you have a point to make.
I would like to encourage informed skepticism. I am disturbed
by skepticism based on personal biases.
http://www.skepticism.net–this is tricky!
The latest posting to this site (April 20, 2004) is dated January
7, 2004. There are 10 headlines on the site.
I see 4 headlines and I say Yes! Yes! Yes!
I see a headline and I say No! No! No!
I see 5 headlines and I say Maybe! Maybe! Maybe! (Need to
read what he is REALLY saying.)
The web page author is “a pro-gun, anti-campaign finance
reform libertarian.” Up-front about it (if you dig a bit).
Why all this time spent on the Who’s Who of the global
warming debate?
“I don’t believe in conspiracy theories. ‘Never attribute to conspiracy what can be
explained by human stupidity.’ Nevertheless, you can’t be too paranoid these
days.”—me
Global Warming: A Definition
Do you think it would be a good idea to know just what the
discussion is about?
How about this for a definition:
“Global warming is the warming of the earth due to the
influence of humans, with a focus on warming due to
emission of greenhouse gases.”
What Do We Know?
1. The Planetary Greenhouse Effect
Without the greenhouse effect, we wouldn’t be alive.
So what is the greenhouse effect?
No, no, no. Not that one. This one:
typo?
Actually, that picture contains at least one common error. This
one, from USA Today, is better (in science content):
I don’t want to nitpick. If you want to say this: “the
greenhouse effect is caused when gases in the atmosphere
behave as a blanket and trap radiation which is then
reradiated to the Earth,” I won’t stop you. But please visit the
bad greenhouse page to see why the sentence is wrong.
Also, a real greenhouse (or car in the sun) gets hot because
heated air is trapped inside it. Not so with the atmosphere.
This is correct: “The surface of the Earth is warmer than it
would be in the absence of an atmosphere because it receives
energy from two sources: the Sun and the atmosphere.”
Anyway, without this “planetary greenhouse effect,” the earth’s
average temperature would be about -18 C (a bit below 0 F)
instead of about 16 C (about 60 F).
The planets give us some idea of the effect of the earth’s
atmosphere on it’s temperature. You can go to planetscapes
and look up planet distances from the sun, and get an
estimate of the average temperature of each planet.
800
700
Mean Temperature (K)
600
500
400
300
200
100
0
0
5
10
15
20
25
Distance From Sun (au)
30
35
40
Let’s focus on the planets out to Jupiter.
800
700
Mean Temperature (K)
600
500
400
300
200
100
0
0
1
2
3
4
Distance From Sun (au)
I’ll discuss this in class!
5
6
I’m getting many of these nice
images from GRID Arendal, an
environmental information center
in Arendal, Norway.
Do you trust Norwegians?
GRID Arendal was established by the Government of Norway
and the United Nations Environment Programme.
Do you trust the United Nations?
Do you trust anybody who spells Program “Programme?”
You can read GRID Arendal’s statement of values here.
If you’re keeping score, the planetary greenhouse effect is real
and significant.
Score:
Global Warming Handwringers
Boss Frogs in our Bucket
1
0
2. Evidence of Past Climate Changes
If we see our climate changing now, maybe we should see
what it has done in the past.
Much of the following material comes from
http://globalwarming.enviroweb.org/. The site’s use of frames
makes it difficult to give a link for each quote.
I’ll do my best to limit the discussion here to topics outside the
global warming political debate.
“Seventy-five million years ago, the Earth's average
temperature was about 10°F (5.6°C) higher than it is today.
Almost everywhere the climate was warm and humid.”
How do we know that? Fossils of
warm-weather plants and animals
living in places where it’s too cold for
them now.
OK, we don’t “know” that, we
“infer” that.
fossils of warm-water sea creatures,
found in South Dakota
In that sense, we don’t “know” a lot about the past other than
through eyewitness reports. And eyewitnesses have been
shown to be the least reliable of all witnesses.
It is inferred that the greater temperature was due to
atmospheric CO2 from volcanic eruptions, and to the fact that
less of the land was above water, so that there were fewer
plants to take in CO2 from the atmosphere.
20,000 years ago, ice covered 1/3 of the earth’s land area, up
to two miles thick in places, and the earth was about 9°F
(5°C) colder than it is now.
How do we know? Fossils of cold-weather
creatures in currently-warm places. We
saw other evidence of the glaciers in the
first video this semester.
Other clues about climate in the past: ice cores, tree rings,
stalagmites, sediments that settled on ocean floors.
Possible reasons for cooling: fewer volcanoes, more land area
covered by plants absorbing CO2, more land area near the
North Pole.
Most of us think of the “Ice Age” as being the last time
glaciers advanced on us from the north, which reached a peak
about 20,000 years ago.
Actually, the geological record shows evidence for repeated Ice
Ages, lasting millions of years each. The current Ice Age is a
couple of million years old. The glacier advance 20,000 years
ago was just one episode of glacier advance during the current
Ice Age.
That’s all I want to discuss about past climate changes right
now. Here are the points I wanted to make...
…and
the
temperature
changes
appear
be correlated
with
Humans
there
have
have
been
been
lucky
huge
to live
climate
during
changes
atoperiod
in the
when
past,
the
the
atmosphere’s
COis2around
content.
without
earth’s
temperature
any humans
moderate
to cause
and its
them
climate
... stable…
This is ammunition for both sides of the political debate:
Humans are not affecting climate: if past climate changes
happened without human intervention, why should the present
be any different?
Humans are affecting climate: if past climate changes are
related to atmospheric CO2, and humans are putting CO2 in
the atmosphere, why should we not expect a change?
Score after the 2nd round:
Global Warming Handwringers
Boss Frogs in our Bucket
1½
½
3. Evidence of Human Influence on the Atmosphere
The claim is that CO2 generated by humans is—or might be—
enhancing the planetary greenhouse effect.
Let’s see how that works.
Every object that has a finite (non-zero) temperature emits
radiation. That radiation can be modeled by something called a
“blackbody”—a perfect absorber and emitter of radiation.
Right now I am emitting and reflecting radiation. You see me
because of the reflected radiation (light). You cannot see the
radiation I am emitting unless you wear night vision goggles.
“Blackbody” is not a politically incorrect term that physicists
have neglected to abandon. It is appropriate because objects
at “normal” temperatures emit this radiation at wavelengths
not visible to the human eye.
The spectrum of blackbody radiation can be calculated easily
using simple quantum mechanics.
It is also easy to make a quite good “blackbody” in the
laboratory; the theoretical and experimental spectra agree
quite nicely.
Here are blackbody spectra for
an object at 37°C (about the
temperature of your skin) and
100°C (boiling water).
All the radiation is in the infrared (invisible, hence “black”).
Above is the spectrum of blackbody radiation from an object at
a temperature of 6000 K—about the surface temperature of
the sun.
If you are on-line, click here for an applet: you control the
thermometer and view the resulting spectrum.
Here’s a measured solar spectrum. It is not smooth like a
blackbody radiation curve because there are other mechanisms
for radiation of energy from the sun.
Intensity (W/m2/m m)
2.50E+03
ASTM E490 Air Mass Zero solar spectral
irradiance is based on data from
satellites (1999)
2.00E+03
1.50E+03
1.00E+03
5.00E+02
0.00E+00
0
1
2
3
4
WaveLength (micro-meters)
5
However, the overall shape is described well by a blackbody
spectrum.
“So what does this have to do with global warming?
Good question. Notice how the amount of energy radiated
depends very strongly on the temperature of the object.
Let’s start off with a cold earth with no
atmposphere and “turn on” the sun.
A cold earth radiates no energy.
As heat from the sun increases the earth’s
temperature, it begins to radiate energy (in
all directions, of course).
The earth will continue to warm up until it
reaches a “steady-state” condition, where
the amount of energy in equals the amount
of energy out.
Now add an atmosphere. The atmosphere
absorbs some of the earth’s energy, warms up,
and radiates energy in all directions.
Now add an atmosphere. The atmosphere
absorbs some of the earth’s energy, warms up,
and radiates energy in all directions.
http://www.usatoday.com/weather/wgrnhse.htm
http://www.grida.no/climate/vital/02.htm
http://globalwarming.enviroweb.org/ishappening/is
happening_frameset.html 20000 yrs ago