[Vision2020] Some reasons I'm skeptical about anthropogenic global warming

[Paul Rumelhart]

Since I feel I've basically made myself into a pariah on this list 
because of my skepticism towards anthropogenic global warming, I thought 
I'd go whole hog and totally alienate myself from all free-thinking 
people by expanding upon my opinion by giving more detail and examples 
of why I'm skeptical.

A Note About Skepticism

Someone who is skeptical about a subject is not the same thing as a 
"denier" or a "contrarian".  A "denier" would be someone who is 
unequivocally stating that the subject is incorrect.  A "contrarian" 
would automatically be stating the opposite conclusion is true, no 
matter what was said.  A skeptic, on the other hand, is merely 
expressing doubt about the topic.  

Thus, I will explain some of my doubts.

Climate vs. Weather

Weather and climate are different, yet related, topics.  In effect, 
climate is an aggregation of weather data over a large period of time.  
How warm is the Earth, today?  Right here, it's very cold.  There are 
blizzards in the mid-west.  In Tokyo, it's 52F.  In Sydney it's 77F.  
These temperatures change quickly over time.  If you took an average 
temperature right now at every weather station on the globe, how good a 
representation of the Earth's temperature would it be?  There are large 
parts of the globe that are a large distance away from a weather 
station.  In some places, you may be a short drive from several.  Factor 
in the temperature of the water in the oceans in various spots and at 
various depths and the temperature of other bodies of water such as 
lakes and rivers and the temperature at various altitudes in our 
atmosphere, and you have a confusing jumble of data that you're trying 
to coalesce into one number.

How useful is that number?  It's presumably useful for long-term trends, 
but may not tell you much on it's own.  How long-term?  A few days?  A 
few months?  A few years?  A few decades?  Longer?  How chaotic is the 
system?  Does that number change fractionally from hour-to-hour, 
day-to-day, or month-to-month?  Does it jump all over the place?  If you 
had a thermometer that was connected to all of these data sources and 
more that could show you the exact averaged temperature at any moment, 
what would it look like?  Would the needle be rock-solid or would it be 
vibrating like mad?

I've learned from playing around with the NCDC global temperature 
datasets that more information does not automatically lead to clearer 
conclusions.

The State of the Data Past 1850 or So

Unfortunately, we don't have data going back before about 1850 that is 
global in scope.  That's about 160 years, which is a small fraction of 
the amount of time we should be looking back.  

The current global temperature data that we do have available comes from 
three places and covers data from around 1850 onward.  Some of it comes 
from NASA's Goddarad Institute for Space Studies, some of it from the 
NOAA's National Climatic Data Center, and some of it from the CRU at the 
University of East Anglia, which is the victim of that data hack (or 
whistle-blowing event) that hasn't been all over the mainstream media.  
The CRU and NCDC datasets are averaged data for the month for each 
station.  I haven't looked at the GISS data yet, so I don't know if it's 
averaged by month or not.

I won't belabor the point about my current mistrust of the CRU dataset 
too much, suffice it to say that since they have "lost" the original raw 
data and don't have methodologies posted that I can find about how they 
made it into their current "value-added" set of data, so I'm pretty much 
discounting it completely.

I am somewhat familiar with the NCDC's dataset, since that's the one 
I've been playing around with plotting. There are stark differences 
between the raw dataset and the adjusted dataset.  Sometime in the 
future I'll have some nice plots that will show these adjustments.  
However, at least we have access to the raw data.  I did dig around on 
the net a little, and came across this: 
http://www.ncdc.noaa.gov/img/climate/research/ushcn/ts.ushcn_anom25_diffs_urb-raw_pg.gif  
Take a look at that graph, and think what would happen if you took any 
old mp3 file and plotted it's waveform as if it's global temperature 
data, then applied that adjustment to it.  What would it show?  Yep, you 
guessed it, global warming.

I'm not familiar with the GISS dataset, so I can offer no conclusions 
about it's trustworthiness.

Another problem is that the stations that provide this data move around 
or change in some other way over time.  What used to be an isolated 
station perfect for measuring weather gets a parking lot put in next to 
it, raising the temperature by 1C.  A station gets moved behind a 
building, too close to an exhaust fan for the air conditioning.  You 
name it, it's happened.  Look at http://surfacestations.org for an idea 
of the quality of data we're getting from these stations.  Take a good 
look at the pie chart labeled "USHCN - Station Site by Quality Rating".  
Notice that with 82% of the sites surveyed, 69% of them are categorized 
as having an error bar of >= 2C, 61% of them as having an error bar of 
 >= 5C.  That's in the US, I don't know how other countries stack up.

The State of the Data Before 1850 or So
 
Well, there isn't much.  Not that I've seen, anyway.  There are probably 
temperature records that go back farther than that, but they are 
sparse.  Before that, it's anecdotal.  Descriptions of storms, bad 
winters or good summers, etc.  Go far enough back, and there is no data 
whatsoever produced by man.

This only gets you back a short amount time compared to the time frame 
of the Earth.  It's just a blink of an eye, geographically speaking.

Temperature Proxies

So how do we graph temperature going back before 1850?  Using 
temperature proxies.  These are measurements that are only indirectly 
related to temperature.  These are things like tree ring growth, coral 
growth, composition of snow, and others.  You basically take some 
natural process that can be measured currently that has a history of 
growth fluctuations over time and try to determine based on what causes 
those fluctuations what the past was like.

The simple example, which is central to some of the debates about the 
CRU email hack, is tree rings.  Trees grow better in certain temperature 
ranges, and they grow a new ring every year.  So you can go back and 
measure the size of the rings to get a basic determination of how well 
the tree grew that year.  That, presumably, gives you some idea of what 
the temperature record was like in the past.

The problem with this is that temperature is not the only variable that 
affects tree growth.  There are other factors which affect this, such as 
moisture, tree placement (how much competition it has for sunlight), 
disease, soil composition, and who knows how many others.  You can 
measure tree rings on a lot of trees to try to average some of these 
factors out that affect individual trees, but you are still stuck with a 
few that should be taken into consideration, such as moisture or 
rainfall.  How much each of these factors affects trees varies by the 
kind of tree that is being sampled.

You take your tree ring growth chart and your reconstructed temperatures 
and you run them against known temperatures for that region (1850 to 
present, if the temperature record there goes back that far), and 
compare the data points.  If there is a good fit, then you have some 
validation that the proxy you are using might be correlated with 
temperature.  This is still doubtful to some degree, because we only 
have a temperature record that covers about 160 years, which may or may 
not be really accurate.  These proxies are being used, by looking at 
fossils of trees, to go back one or two thousand years.

The controversy about "hide the decline" that you may have heard about 
has to do with tree rings for pine trees in Yamal in Siberia.  
Apparently, if you compare the reconstruction with current temperature 
records, you get a pretty good fit until about 1960 or so.  After that 
point, the reconstructed temperature falls off while the temperature 
record goes up.  The trick to hide the decline had to do with splicing 
the temperature record onto the reconstructed temperature record at 1960 
and smooth the curve, then cut it at 1960 in order to make the curve 
that ends at 1960 appear to be curving up instead of down.  There is a 
good explanation of this here: 
http://wattsupwiththat.com/2009/11/20/mikes-nature-trick/  In my 
opinion, that discrepency (50 years over at most 160 years don't fit) 
should have signaled to them that that proxy was not a good proxy for 
temperature.  Instead, they tried to make it appear that it fit better 
than it did, so that they could show that the remainder of the 
reconstruction record before 1850 was more valid than it would otherwise 
appear to be.  Another criticism I've seen about this study is that they 
used a small number of trees to get their data points.  Twelve trees, I 
think.  That's obviously not enough to get an accurate reconstruction, 
even if tree rings are a good proxy for temperature.

The Medieval Warm Period and the Little Ice Age

Why did they try so hard to make their reconstruction look better than 
it did?  Because they wanted to minimize the "Medieval Warm Period" and 
the "Little Ice Age".  This came out in the hacked emails.  Here is an 
explanation of this from a blog post: 
http://wattsupwiththat.com/2009/12/06/american-thinker-understanding-climategates-hidden-decline/  


The MWP was a period of time (about 800 - 1300 AD) during which the 
temperature of the Earth appeared from historical writings to be at 
least as high as the current temperature or even higher.  The LIA was a 
period of time from about 1500 or so to 1850 during which temperatures 
were low and slowly climbing, with minimal temperatures at various 
points interspersed with periods of slight warming.

There is evidence that both of these phenomena were global in scale, 
although the exact periods of time change a bit in different areas of 
the Earth.  You have the Vikings colonizing Greenland and farming there 
for 400 years, and you have various other measurements that coincide 
with this.  The Wikipedia article on MWP has a handful of them: 
http://en.wikipedia.org/wiki/Medieval_warm_period  For example, here is 
a link to a description of an article that was published in Nature that 
describes how the Indo-Pacific Warm Pool may have been as warm during 
the MWP as it is today: http://www.physorg.com/news170598165.html

So why try to minimize the MWP and the LIA?  Look at how it frames the 
debate.  If it was naturally warmer one thousand years ago than it is 
now, and we're recovering from a severe cold bout that has lasted 600 
years, then global warming can be seen as a natural correction to the 
LIA.  Furthermore, life during the MWP was prosperous, not some sort of 
hell on earth that killed billions.  It's much more profitable and much 
more ego-building to show that you are trying to save the world from a 
mistake that we as a species has made, since we can presumably do 
something about it.  That's why I am skeptical of these tree ring 
proxies and our ability to state with any confidence exactly what the 
temperatures were like.  

Conclusions

Well, I was going to write about Climate Model accuracy, Milankovich 
Cycles, the Maunder Minimum, the Earth's history of Ice Ages and a few 
other topics, but this has already turned into a book.  Look them up if 
you're curious.  

So, basically, I'm doubtful of the following things, to one degree or 
another:

Our ability to accurately graph global temperature with accuracy over 
extended periods of time and have it mean much.

The "adjustments" made to the three basic datasets that we use for 
plotting temperature.

The accuracy of our current temperature measurements used in these datasets.

Our ability to accurately reconstruct temperature before 1850 based on 
various temperature proxies.

The predictive ability of tree-ring proxies in particular and their 
explanatory ability for past temperatures.

The removal of the Medieval Warm Period from the temperature record, and 
indeed our general idea of what temperature has been like over the last 
2000 years.

Now, on to what I'm not saying.  I'm not saying that the Earth is not 
warming.  It seems pretty clear that it is warming, or has been since 
1850, generally speaking.  I'm not saying that carbon dioxide does not 
have an affect on temperature, or that man is not having an affect in 
other ways as well.  I'm not saying that massive amounts of CO2 aren't 
harming our oceans.

But I am skeptical about the science being "settled", and I'm skeptical 
that we have enough of an understanding of the problem to warrant the 
massive media campaign that is currently going on and the massive 
expenditures that could come out of Copenhagen.  There is room for doubt 
here about a lot of things.  Let's do more science.

In twenty years, when it's all been proven and it turns out that the AGW 
hypotheses were correct, will I feel like an idiot for being skeptical 
of it now?  No.  In my opinion, the question is still up in the air and 
I won't feel even a little bit chagrined then for doubting some of their 
conclusions now.  How would some of these scientists handle the opposite 
answer 20 years from now, I wonder?

Paul

My apologies for the long post.