

Global Warming vs. Clojure - abscondment
http://www.bestinclass.dk/index.php/2010/01/global-warming/

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baguasquirrel
_So all we need to do in order to follow these stations, is filter out those
in the northern hemisphere and re-run the job._

Isn't this the same sort of thing that the tree ring people did? There were
some statistical points that looked like they were going to mess with the
results so they threw them out? They only threw out a few outliers, which is
standard practice, but here we're throwing out a whole class of data.

It's also interesting that the northern hemisphere is warming up faster (if
the methodology chosen by the author is correct). Since most of the earth's
landmass is on the northern hemisphere (as well as most of the developed
countries), doesn't that mean we're in trouble?

 _By looking at each station indiviually instead of compressing them to an
unevenly weighted average, we will be able to clearly deduce how the weather
has changed through the years recorded._

This still doesn't take into account the density of stations. Also, trying to
compare stations like that, with the curves obscuring each other, is a crime
of presentation. If you took the time to do a regression on the datapoints
with the other data, it surely would not have took much longer to code for
regression on each of the individual weather stations (incorrect as that may
be).

On a different note, the use of clojure was enjoyable, which deserves an
upmod.

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Zarkonnen
As I understand it, the tree ring thing was that the more recent data is
distorted by pollution. That is, the width of each year's ring should be
dependent on how warm the year was, but the increase in pollution in recent
times has caused a decrease in the width of the rings laid down.

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dantheman
There are a lot of problems with tree ring data, two of the most important
are:

1\. It no longer corresponds to the temperatures we measure (last 50 years or
so)

2\. It is based on very few trees,

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skorgu
I'm torn on this article. I'm very appreciative of a real-world example of
using clojure to manipulate data but at the same time it treats a trivial and
entirely unscientific analysis of one data set as a complete, concrete and
comprehensive summary of an entire field of science.

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mey
I agree, I just choose to enjoy the presentation of clojure and ignore the
conclusion. :)

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holygoat
That's not a very reasoned approach to contradictory conclusions.

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zzkt
is a non sequitur an acceptable straw man?

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brc
Well, there's a few problems. Gore didn't actually use the Mann hockey stick
that is presented, although the hockey stick in 'An Inconvenient Truth' is
very simliar (in that it omits the Medieval Warming Period)

Those commenting on the start date fail to realise that the start date of the
data set he uses is 1929. You can't blame the author for that.

The fact that it's part of the 'head' or 'blade' of the stick is irrelevant,
all of the 'handle' is based on multi-proxy reconstruction, which has major
data problems, as the endless to-and-fro on this issue says. One of the major
problems highlighted has been the use of tree-rings as a proxy, and the tree
rings do not agree with the instrumental record. This is the famous 'hide the
decline', where the authors sought out statistical methods (the trick) in
order to splice the tree ring proxies with the instrumental records, which
they really shouldn't have done.

The field of coming up with global averages from temperature datasets is so
complex I won't even try and make a comment on that. Plus I don't know any
clojure.

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tjic
My first thought upon seeing the title to the post:

Q: What's the difference between Global Warming and Clojure?

A: Clojure is real.

~~~
jacquesm
By implication you're saying global warming is not real, and that's not true,
global warming _is_ real.

The questions center around how much of it is due to our influence and if we
are capable of doing something about it.

~~~
fleitz
There is also the question of whether the net effect of the warming is a
negative economic impact, and if so if "fixing" it is a greater cost to the
economy than not fixing it.

~~~
jacquesm
That's very true. It may very well have a net positive economical effect.

But the problem with that kind of reasoning is that if it is going to have a
net positive economic effect that we can rape & plunder mother nature to our
hearts content and that simply isn't true.

Economic advantages are not all there is to look after, long term effects are
important, and the absolute effect on economies is also important. In other
words if our economy goes up because of doing something and some poor country
loses all they've got then you could argue the net effect is positive because
they didn't have much to begin with.

But that's definitely not how the world should work.

So we need to look past purely economic motives and at humanity (and to some
extent the biosphere) as a whole.

Beancounters are bad stewards of ecologies.

~~~
jacoblyles
>"But the problem with that kind of reasoning is that if it is going to have a
net positive economic effect that we can rape & plunder mother nature to our
hearts content and that simply isn't true."

I doubt that any serious environmental economist thinks this way. Economists
do include non-monetary factors in cost/benefit analsyes, and the cost of
environmental degradation which does NOT show up on profit/loss statements is
one of the oldest topics in the field.

Dismissing the entire discipline of environmental economics as the work of
"bean counters" is a really bad rhetorical start for any serious discussion of
ecological policy, though unfortunately it happens often among the masses on
internet message boards. I am really disappointed to see that these
caricatures abound.

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jacquesm
There are many examples of very precious resources being squandered because of
profit motives, our stewardship of the planet could be _much_ better, I doubt
it could be much worse.

In less than 300 years, basically since the time that we started to
industrialize we have remade face of the planet.

Point me to all those efforts at sustained management that ought to be a
counterexample to those examples of wanton destruction of habitats and
ecosystems for profit.

Everywhere that money is brought in to the equation sooner or later the
ecology will have to suffer. Running an ecology as a business is simply not an
option.

I know it has been tried many times and I know that there are plenty of people
that probably have the best interest of their environment at heart, but from
what I've seen to date the best thing we have done is to simply _not_ mess
with a large enough area and hope that it will recover.

Any attempt at large scale intervention, even from a positive viewpoint has
sooner or later become a game of seeing how to use that resource within the
letter of the law for maximum profit.

Rainforests, the Canadian forest management, wildlife preserves, the artic and
the oceans.

The list really is endless.

Calling the people in charge bean counters is doing them a service, it means
they're not actively involved in destruction on a planetwide scale that they
are aware of.

I even leave open room for 'best intentions', but that doesn't mean their
effects are positve. Not by a long shot.

Right now those places that are doing best in terms of species diversity and
other parameters indicating relatively healthy ecosystems are those that we
haven't gotten around to yet and those that we have utterly abandoned.

Environmental economics is a complete contradiction, you can not manage a
tract of rainforest or a volume of ocean in a way that is at the same time
good for the environment and ecologically sound.

We have basically taken out an environmental mortgage and have spent that
mortgage on stuff that harms the environment, it will be a long long time
before we are in a position to pay it back.

I realize this is not a happy picture, but sometimes it is better to open your
eyes to what's really going on than to put on your rosy sunglasses and to hope
that it will all go away.

There are lots of very uncomfortable conclusions that we may one day have to
draw, there is a small chance that we will be in a position to guide those
decisions if we start acting long enough in advance.

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jacoblyles
>"There are many examples of very precious resources being squandered because
of profit motives"

Ah, yes, the Tragedy of the Commons:

<http://en.wikipedia.org/wiki/Tragedy_of_the_commons>

You are right that people have damaged the environment for personal gain in
the past, but I still think that you are missing the point on what economics
is about. In environmental economics researchers study why people use
resources the way they do, how to design environmental regulation so that
people will actually stick to it, and what resource use is likely to be in the
future. "How to rape the environment more efficiently" is not a common topic
of study.

Sorry, environmental economics was probably the wrong field to bring up. What
we really want to know is whether or not these macroeconomic modelers take
into account the value of ecological resources in their models. Tell you what,
I'll scribble off a note to William Nordhaus and ask him. In my experience
most academic economists have been very approachable.

Here's my letter:

" Hello Dr. Nordhaus,

I have a question about the economic modeling of climate change. Do economists
take into account the cost of ecological damage in their models?

I ask because this question came up in conversation a few days ago. A friend
of mine claimed economic models were invalid because they only took into
effect the monetary profit-and-loss effects of climate change and not the
value of nature itself, but I wasn't sure if that was true. How does a
resource like the Brazilian Rainforest enter into the model?

Thanks,

Jacob"

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jacoblyles
Hi,

I got a reply back from Dr. Nordhaus today:

"The answer is that these are included conceptually in serious studies. The
problem is that measurement has proven extremely difficult, so it is hard to
judge whether the actual magnitudes are correct. WN"

I think it makes the case that economists do not consider ecological damage to
be cost zero. However, it is hard to assign a hard objective value to it.

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mark_l_watson
I just tagged this excellent article on delicio.us - description: "Awesome
example of using Clojure for data manipulation!"

A good read, and I bet that a few of the code snippets in the article will
save me coding time.

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abscondment
Totally.

The article is a good read regarding data crunching, but I take exception to
some of his methodology.

Specifically, he's only using data from 1929 and on -- this is all part of the
hockey stick's head. The 1920s are supposedly the start of the dramatic
temperature increase. So of course the graphs don't show a dramatic slope
change; there's no pre-1929, lesser-slope data included.

Edit: I'm _not_ implying intentional omission on his part; 1929 is the
earliest year available from NOAA (ftp://ftp.ncdc.noaa.gov/pub/data/gsod).

~~~
jacquesm
Exactly. That's about as selective as you can get.

No way of saying that hockey stick will appear if he includes all the data but
the way he filtered out the end part and then stretched it is just being very
selective with the data provided.

The reason why there is so much room for interpretation in all this data
crunching in part is because of the troublesome normalization issues faced
when consolidating data from so many different sources.

If there had been reliable weather stations in the last two millennia this
would be completely different. But obviously that's not the case.

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motters
I have a project based on the Global Historical Climatology Network data,
going back 300 years. This is based upon readings from actual thermometers on
ground based weather stations, rather than tree rings or ice cores which are
far more difficult to decypher.

<http://code.google.com/p/tempgraph/>

You can graph the data in various ways, all the way down to individual weather
stations.

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Kaizyn
We (humanity) have reliable temperature data as measured by a thermometer and
at fixed locations going back 300 years?

~~~
skorgu
We don't have temperature data measured by a thermometer at fixed locations
for _50_ years. There are many other sources of temperature data.

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motters
The thing is that when you look at the data at the lowest level (individual
stations) what you're getting is small snippets of temperature information.
Some stations have been around for as long as 100 years, but I don't think
that there are any single stations which span the full 300 years.

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yannis
Excellent read! Does anyone know of any study that extrapolates global
temperatures from Landsat images?

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alrex021
I don't get this title. (In "1 line" of plain text) ;-)

[edit] jokes aside, its actually a good read.

