Medieval Global Warming A controversy over 14th century cli

Main Page | Report this Page

Science Forum Index » Environment Forum » Medieval Global Warming A controversy over 14th century cli

Page 1 of 1

Author

Message

Aozotorp

Posted: Wed Dec 17, 2003 7:00 am

Guest

http://www.technologyreview.com/articles/wo_muller121703.asp

Medieval Global Warming
A controversy over 14th century climate shows the peril of letting politics
shape the scientific debate.

By Richard Muller
Technology for Presidents
December 17, 2003

Six hundred years ago, the world was warm. Or maybe it wasn’t. What’s the
truth? Beware. This question has recently been elevated from a mere scientific
quandary to one of the hot (or cold) issues of modern politics. Argue in favor
of the wrong answer and you risk being branded a liberal alarmist or a
conservative Neanderthal. Or you might lose your job.

Six editors recently resigned from the journal Climate Research because of this
issue. Their crime: publishing the article "Proxy Climatic and Environmental
Changes of the Past 1,000 Years," by W. Soon and S. Baliunas of the
Harvard-Smithsonian Center for Astrophysics.

Without passing judgment on this particular paper, I can still point out that
our journals are full of poor papers. If editors were dismissed every time they
published one, they would all be out of work within a month or two. What made
the Soon and Baliunas situation different is that their paper attracted
enormous attention. And that’s because it threw doubt on the hockey stick.

If you don’t know what the hockey stick is, do a Google search, including the
word “climate.” You’ll learn that it is the nickname for a remarkable
graph that has become a poster child for the environmental movement. Published
by M. Mann and colleagues in 1998 and 1999, the plot showed that the climate of
the Northern Hemisphere had been remarkably constant for 900 years until it
suddenly began to heat up about 100 years ago—right about the time that human
use of fossil fuels began to push up levels of atmospheric carbon dioxide. The
overall shape of the curve resembled a hockey stick laying on its back—a
straight part with a sudden bend upwards near the end.

The hockey stick was turned from a scientific plot into the most widely
reproduced picture of the global warming discussion. The version below comes
from the influential 2001 report of the Intergovernmental Panel on Climate
Change (IPCC). The hockey stick figure appears five times in just the summary
volume alone.

The “hockey stick”
(from the IPCC 2001 report)

Soon the graph acquired a very effective sound bite: 1998 was the warmest year
in the last thousand years. This carried a compelling conclusion: global
warming is real; humans are to blame; we must do something—hurry and ratify
the Kyoto treaty on limitations of fossil fuel emissions. Yet some scientists
urged caution, a go slow approach. As a wise man once warned, “do not let the
merely urgent interfere with the truly important.”

There was a minor scientific glitch. The hockey stick contradicted previous
work that had concluded that there had been a “medieval warm period.” In
fact, it disagreed with a plot published by the IPCC itself a decade earlier
(in its 1990 report) that showed pronounced warm temperatures from the years
1000 to 1400.

Such inconsistencies are common in science, and scientists love them. They mean
more work, maybe a little public attention (which can’t hurt funding), and
the excitement that comes with the effort to resolve uncertainty. The Soon and
Baliunas paper was part of this process. Their paper presented all the data in
favor of the medieval warm period.

The debate grew. Critics of Soon and Baliunas charged that their paper wasn’t
balanced; because it consisted of a compilation of data showing warming at
different locations at different times, the criticism went, the work was not a
valid refutation of the hockey stick analysis, which had combined a much larger
set of data. That was a valid concern, but it didn’t necessarily mean that
the Soon and Baliunas results should be ignored. It simply meant that the
issue was still open.

Meanwhile, critics excoriated Climate Research for allegedly failing to vet the
Soon and Baliunas paper properly. The publisher, a German company called
Inter-Research, agreed, leading to the resignation of the journal’s
editor-in-chief and, eventually, five other editors.

Then last month the situation became even more complex. S. McIntyre and R.
McKitrick published a paper in Energy and Environment with a detailed critique
of the original hockey stick work. They stated bluntly that the original Mann
papers contained “collation errors, unjustifiable truncations of
extrapolation of source data, obsolete data, geographical location errors,
incorrect calculations of principle components, and other quality control
defects.” Moreover, when they corrected these errors, the medieval warm
period came back—strongly. Mann, et al., disagreed. They immediately posted a
reply on the Web, with their criticism of McIntyre and McKitrick’s analysis.

The disagreement is not political; most of it arises from valid issues
involving physics and mathematics. First the physics. An accurate thermometer
wasn’t invented until 1724 (by Fahrenheit), and good worldwide records
didn’t exist prior to the 1900s. For earlier eras, we depend on indirect
estimates called proxies. These include the widths of tree rings, the ratio of
oxygen isotopes in glacial ice, variations in species of microscopic animals
trapped in sediment (different kinds thrive at different temperatures), and
even historical records of harbor closures from ice. Of course, these proxies
also respond to other elements of weather, such as rainfall, cloud cover, and
storm patterns. Moreover, most proxies are sensitive to local conditions, and
extrapolating to global climate can be hazardous. Chose the wrong proxies and
you’ll get the wrong answer.

The math questions involve the procedures for combining data sets. Mann used a
well-known approach called principle component analysis. This method extracts
from a set of proxy records the behavior that they have in common. It can be
more sensitive than simply averaging data, since it typically suppresses
nonglobal variations that appear in only a few records. But to use it, the
proxy records must be sampled at the same times and have the same length. The
data available to Mann and his colleagues weren’t, so they had to be
averaged, interpolated, and extrapolated. That required subjective judgments
which—unfortunately—could have biased the conclusions.

When I first read the Mann papers in 1998, I was disappointed that they did not
discuss such systematic biases in much detail, particularly since their
conclusions repealed the medieval warm period. In most fields of science,
researchers who express the most self-doubt and who understate their
conclusions are the ones that are most respected. Scientists regard with
disdain those who play their conclusions to the press. I was worried about the
hockey stick from the beginning. When I wrote my book on paleoclimate
(published in 2000), I initially included the hockey stick graph in the
introductory chapter. In the second draft, I cut the figure, although I left a
reference. I didn’t trust it enough.

Last month’s article by McIntyre and McKitrick raised pertinent questions.
They had been given access (by Mann) to details of the work that were not
publicly available. Independent analysis and (when possible) independent data
sets are ultimately the arbiter of truth. This is precisely the way that
science should, and usually does, proceed. That’s why Nobel Prizes are often
awarded one to three decades after the work was completed—to avoid mistakes.
Truth is not easy to find, but a slow process is the only one that works
reliably.

It was unfortunate that many scientists endorsed the hockey stick before it
could be subjected to the tedious review of time. Ironically, it appears that
these scientists skipped the vetting precisely because the results were so
important.

Let me be clear. My own reading of the literature and study of paleoclimate
suggests strongly that carbon dioxide from burning of fossil fuels will prove
to be the greatest pollutant of human history. It is likely to have severe and
detrimental effects on global climate. I would love to believe that the results
of Mann et al. are correct, and that the last few years have been the warmest
in a millennium.

Love to believe? My own words make me shudder. They trigger my scientist’s
instinct for caution. When a conclusion is attractive, I am tempted to lower my
standards, to do shoddy work. But that is not the way to truth. When the
conclusions are attractive, we must be extra cautious.

The public debate does not make that easy. Political journalists have jumped
in, with discussion not only of the science, but of the political backgrounds
of the scientists and their potential biases from funding sources. Scientists
themselves are also at fault. Some are finding fame and glory, and even a sense
that they are important. (That’s remarkably rare in science.) We drift into
ad hominem counterattacks. Criticize the hockey stick and some colleagues seem
to think you have a political agenda—I’ve discovered this myself. Accept
the hockey stick, and others accuse you of uncritical thought.

There are also the valid concerns of politicians who have to make decisions in
a timely way. In 1947, Harry Truman grew so annoyed at the prevarications of
economists that he joked that he wanted a one-armed advisor—who could not
hedge his conclusions with the phrase “on the other hand.”

Some people think that science is served by open debate between left-handed and
right-handed advocates, just as in politics. But the history of science shows
it is best done by people who have two hands each. Present results with
caution, and insist on equivocating. Leave it to the president and his advisors
to make decisions based on uncertain conclusions. Don’t exaggerate the
results. Use both hands. We cannot afford to lower our standards merely because
the problem is so urgent.

Richard A. Muller, a 1982 MacArthur Fellow, is a physics professor at the
University of California, Berkeley, where he teaches a course called “Physics
for Future Presidents.” Since 1972, he has been a Jason consultant on U.S.
national security

Ian St. John

Posted: Wed Dec 17, 2003 12:36 pm

Guest

"Aozotorp" <aozotorp@aol.com> wrote in message
news:20031217070045.12131.00001113@mb-m05.aol.com...

Quote:

Not a problem I argue very convincingly that there is no source of the
billions of quads of energy needed to produce an earth warmer by several
degrees over a few decades. No evidence of such a monstrous influx of energy
( obviously not the current greenhouse effect which took massive increases
in industry and a century to get the world a mere 0.6C warmer ) Ego, the
most likely hypothesis is that this was a regional warming, which has since
been supported by regional assessments of dendrochronology records.

Quote:

Or you might lose your job.

They weren't fired. If you will look at the quote you will find they
resigned in shame over their mistakes.

Quote:

Six editors recently resigned from the journal Climate Research because of
this
issue. Their crime: publishing the article "Proxy Climatic and
Environmental
Changes of the Past 1,000 Years," by W. Soon and S. Baliunas of the
Harvard-Smithsonian Center for Astrophysics.

They should have been fired given their sloppy review of the publication
which did not support it's conclusions with it's findings. The whole
reputation of the journal rest on elimination of bad sciences so people can
have confidence in the quality of articles.

Quote:

Without passing judgment on this particular paper,

Avoiding the issue that is central to this???

Quote:

I can still point out that
our journals are full of poor papers. If editors were dismissed every time
they
published one, they would all be out of work within a month or two. What
made
the Soon and Baliunas situation different is that their paper attracted
enormous attention. And that's because it threw doubt on the hockey stick.

No. The central issue is that it FALSELY tried to claim doubt on the Mann,
et all 1999 reconstruction, and in fact all of the reconstructions by all of
the authors. The absurd name of 'hockey stick' has nothing to do with the
quality of the research or the soundness which has beeen peer reviewed. The
fact that Soon and Baliunas got 'caught' with their fake research shows that
the journals DO keep most of the shit out.

<meaningless description of colloquial 'descriptive phrase' deleted>
<snip>

Quote:

The hockey stick was turned from a scientific plot into the most widely
reproduced picture of the global warming discussion. The version below
comes
from the influential 2001 report of the Intergovernmental Panel on Climate
Change (IPCC). The hockey stick figure appears five times in just the
summary
volume alone.

And yet it is just 'historical reference' that might mean something to the
public and confirmation that the current warming is out of character for the
planet, a conclusion that is supportable on the basis of many facts.

<more meaningless and perjorative shit deleted>

Guest

Posted: Wed Dec 17, 2003 5:23 pm

Ian St. John <istjohn@noemail.ca> wrote:

Quote:

"Aozotorp" <aozotorp@aol.com> wrote in message
http://www.technologyreview.com/articles/wo_muller121703.asp

They weren't fired. If you will look at the quote you will find they
resigned in shame over their mistakes.

Six editors recently resigned from the journal Climate Research because of
this
issue. Their crime: publishing the article "Proxy Climatic and
Environmental
Changes of the Past 1,000 Years," by W. Soon and S. Baliunas of the
Harvard-Smithsonian Center for Astrophysics.

They should have been fired given their sloppy review of the publication
which did not support it's conclusions with it's findings.

As I understand it, they resigned because they believed that the journal
was incorrect to have published the paper, and to have failed
to publish von S's editorial criticising the process.

You're wrong to say its any personal shame on them: journals have
muliple editors, its unlikely they had anything to do with the
paper pre-publication.

They resigned because they didn't want to be associated with the
journal, not because of any failings on their part.

-W.

--
William M Connolley | wmc@bas.ac.uk | http://www.antarctica.ac.uk/met/wmc/
Climate Modeller, British Antarctic Survey | Disclaimer: I speak for myself
I'm a .signature virus! copy me into your .signature file & help me spread!

Guest

Posted: Wed Dec 17, 2003 5:27 pm

Aozotorp <aozotorp@aol.com> wrote:

Quote:

http://www.technologyreview.com/articles/wo_muller121703.asp

There was a minor scientific glitch. The hockey stick contradicted previous
work that had concluded that there had been a “medieval warm period.” In
fact, it disagreed with a plot published by the IPCC itself a decade earlier
(in its 1990 report) that showed pronounced warm temperatures from the years
1000 to 1400.

But oddly enough that graph didn't appear in the 1992 supplementary
report, or the 1995 report, though both of these predate Mann's work.
Why not? Because the graph in question (fig 7.1?) is a "schematic" and
completely unsourced. If IPCC should be attacked for anything, its for
including an unsourced graph in the first place in 1990.

Quote:

Meanwhile, critics excoriated Climate Research for allegedly failing to vet the
Soon and Baliunas paper properly. The publisher, a German company called
Inter-Research, agreed, leading to the resignation of the journal’s
editor-in-chief and, eventually, five other editors.

This is misleading: see my other post. The Editor-in-chief resigned
because CR wouldn't publish his editorial criticising the review process
for S+B

-W.

--
William M Connolley | wmc@bas.ac.uk | http://www.antarctica.ac.uk/met/wmc/
Climate Modeller, British Antarctic Survey | Disclaimer: I speak for myself
I'm a .signature virus! copy me into your .signature file & help me spread!

Page 1 of 1 All times are GMT - 5 Hours The time now is Tue Oct 07, 2008 11:39 pm Science Forum Index