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[Geoff Davis <geoff AT geoffdavis.net>]

I have seen "An Inconvenient Truth" and thought it was very well done.
I think Gore does a nice job of making the highlights of the current
understanding of climate change both accessible and interesting; the
film also provides a compelling look at Gore's own background and
reasons for being passionate about the issue.  It would make a good
group activity -- certainly it would lead to some interesting
discussions.

Out of curiosity, I decided to read the junkscience link that was sent
out earlier.  It's a a pretty interesting study in propaganda.

Some background: I have a PhD in applied math and taught math/stats as a
professor for a few years.  My graduate coursework included a lot of
work on numerical simulations of physical systems, including a semester
doing weather modeling, so I have some appreciation for the tremendous
amount of effort that has gone into current climate models; I also have
an appreciation for the difficulties involved in getting things right.

>From my experience, the scientific community is full of smart, dedicated
people with tremendous integrity who are devoted first and foremost to
seeking out the truth.  People do make mistakes, and there is occasional
fraud and misconduct, but the system is effective at correcting itself
over time.  The current understanding of climate change involves the
work of many, many people in many different fields.  There is very
little incentive to support the idea of global warming for any reason
other than the fact that the data points that way; there are plenty of
financial reasons to oppose it (a few major corporations have been very
generous to skeptics).  In spite of this, there is a strong consensus
that global warming is real.

Suppose I wanted to discredit some scientific finding.  I'd have two key
tasks: I would have to establish myself as an authority on the subject,
and I would have to discredit existing authorities.  I'd have to be
careful not to include anything obviously false so that I could not be
refuted easily.  A few techniques I could use to accomplish these
things:
* Focus on things that are true but irrelevant
* Drop a few names here and there so it sounds like I'm quoting
authorities, but use no real bibliographic references so it's difficult
to verify any claims I make
* Pull materials out of context
* Make no distinction between questionable sources and authoritative
ones 

Before digging in, I thought it would be important to get a sense of
what kind of motivations the author of a piece like this might have.  Is
he somebody knowledgeable?  Does he have any kind of agenda?  A bit of
googling on Steven Milloy turns up this (and a lot of similar things):
http://www.sourcewatch.org/index.php?title=Steve_Milloy
In short, the author has spent a good chunk of his career working for
Philip-Morris trying to discredit research on the dangers of second-hand
smoke.  I place a lot more trust real scientists
(http://www.cnn.com/2006/HEALTH/06/27/involuntary.smoking.ap/index.html ) 
than in tobacco lobbyists, but others may differ.  More recently, he has 
received a lot of funding from Exxon-Mobil, a corporation that presumably 
perceives that political action on global warming will hurt its bottom line.

A read through the article shows a lot of the techniques outlined above.

* Greenhouse gases don't turn the atmosphere into a literal greenhouse!!
These gases don't form a literal blanket!! [true but irrelevant]

* Some of the warming effects of C02 are good! [true but irrelevant --
too much of a good thing, etc]

* Don't forget convection!! [true but irrelevant; also jargon
establishing authority]

* Water vapor is also a greenhouse gas! [true but irrelevant; see
http://www.gcrio.org/ipcc/qa/09.html ]

* Humans aren't the only source of CO2 [true but irrelevant -- we're the
main source of the current increase]

* Plants need CO2!  [true but irrelevant -- too much of a good thing]

* Temperature changes are small compared to measurement errors [possibly
true but irrelevant]  Milloy's statements along these lines are what
convince me that he is being willfully misleading.  Elementary
statistics teaches you how to detect small changes from a large pool of
measurements even when there is a lot of variation in individual
measurements.  Milloy has a master's in biostatistics so he knows this.

And on and on.  Throughout Milloy kicks around author names to suggest
he's citing real literature, but he provides few complete references so
that it's a pain for anyone to follow up and verify anything he says.

His main take-home is that warming of 1 degree Celsius is no big deal
and that larger estimates are bogus because of uncertainties in the
models.

1 C certainly doesn't sound like much.  After all, the planet has
already warmed by 0.6 C since 1850.  (By the way, 1 C is a lowball
figure for projected warming over the next century -- according to
wikipedia, the currently accepted range is 1.4 C to 4.5 C).  Even so,
how much could that matter? 

The 0.6 C increase since 1850 has already caused noticeable effects.
Because of the way heat is transported across the planet, warming is
non-uniform.  The poles heat up faster than the equator, and we have
seen pretty substantial glacier melts in both the Arctic and Antarctic.
The film shows lots of examples.

As Milloy notes, temperatures have changed by a 1 C or so at various
points in the past.  From the planet's point of view, it's no big deal.
However, to put this in human perspective, a series of temperature drops
between the 13th-19th centuries of less than 1 C is called the Little
Ice Age.  The drops led to the extinction of the Norwegian settlers in
Greenland and to the Great Famine of 1315-1317 that killed millions in
Europe (see http://en.wikipedia.org/wiki/Little_ice_age ).  Other
relatively modest climactic variations are thought to have been major
contributors to the collapse of the Mayan civilization and of the
Anasazi.  Imagine what might happen if the high-end warming predictions
come to pass.

While there are surely uncertainties and errors in current climate
models, they represent the best scientific estimate of what greenhouse
gases will do.  Ignoring the models amounts to a belief in an implicit
model of one's own: that nothing will change.  I personally prefer to
put my belief in models based on science, no matter how appealing the
corporate-funded alternative.

Whenever science and policy intersect, there is the potential for
similar kinds of push-back.  There are still people who don't believe
that HIV causes AIDS, for instance, and their influence has led to
disastrous public health policies in South Africa.  Let's hope that
science fares a bit better in the case of global climate change.
Teaching basic media literacy so that people are more able to recognize
this kind of propaganda would be a good start.

In any case, do see the film -- it's sobering but guardedly optimistic.

Geoff