It is sad that Janice relies on second hand reporting rather than on
reading the report by the NAS to come to a full understanding of these
issues.
First of all, there is still no evidence of fraudulent data, despite
Janice's promises to provide such evidence.
Secondly, the NAS report, which is freely available to anyone
interested, does report that it disagrees with some of the claims by
Mann
For instance
<quote>In addition, the NAS report further chastises Mann, declaring
"Even less confidence can be placed in the original conclusions by
Mann et al. (1999) that 'the 1990's are likely the warmest decade, and
1998 the warmest year, in at least a millennium ...'" </quote>
Note the ellipses... What the NAs reports is that statistically
speaking such a comment is full of pitfalls since there are large
uncertainties associated with individual years.
So lets read the whole paragraph in context and determine whether or
not the NAS disagreed with Mann and to what extent:
<quote>
Based on the analyses presented in the original papers by Mann et al.
and this newer supporting evidence, the committee finds it plausible
that the Northern Hemi-sphere was warmer during the last few decades
of the 20th century than during any comparable period over the
preceding millennium.
</quote>
Score 1 for Mann
<quote> The substantial uncertainties currently present in the
quantitative assessment of large-scale surface temperature changes
prior to about A.D. 1600 lower our confidence in this conclusion
compared to the high level of confidence we place in the Little Ice
Age cooling and 20th century warming.
</quote>
Note that the report lowers their confidence prior to AD 1600
<quote>
Even less confidence can be placed in the original conclusions by Mann
et al. (1999)
that "the 1990s are likely the warmest decade, and 1998 the warmest
year, in at least
a millennium" because the uncertainties inherent in temperature
reconstructions for
individual years and decades are larger than those for longer time
periods and because
not all of the available proxies record temperature information on
such short timescales.
</quote>
Again, in context the comments are slightly different from what one
would have expected from reading Janice's indirect source.
<quote>
Surface temperature reconstructions for periods prior to the
industrial era are only
one of multiple lines of evidence supporting the conclusion that
climatic warming is
occurring in response to human activities, and they are not the
primary evidence.
</quote>
Score 2 for Mann
Now, as I have said in the past, as Christians we have to be careful
in accepting without skepticism, indirect, third hand reports and
should rely as close as possible on the actual original sources.
In this case, the original sources clearly contradict Janice's claims.
although I cannot fault her for relying on what she may have
erroneously considered 'credible sources', although a quick research
on the internet would have revealed the rest of the story.
The NAS Conclusions
<quote>
The instrumentally measured warming of about 0.6°C during the 20th
century is also reflected in borehole temperature measurements, the
retreat of glaciers, and other observational evidence, and can be
simulated with climate models.
• Large-scale surface temperature reconstructions yield a generally
consistent picture of temperature trends during the preceding
millennium, including relatively warm conditions centered around A.D.
1000 (identified by some as the "Medieval Warm Period") and a
relatively cold period (or "Little Ice Age") centered around 1700. The
existence of a Little Ice Age from roughly 1500 to 1850 is supported
by a wide variety of evidence including ice cores, tree rings,
borehole temperatures, glacier length records, and historical
documents. Evidence for regional warmth during medieval times can be
found in a diverse but more limited set of records including ice
cores, tree rings, marine sediments, and historical sources from
Europe and Asia, but the exact timing and duration of warm periods may
have varied from region to region, and the magnitude
and geographic extent of the warmth are uncertain.
It can be said with a high level of confidence that global mean
surface temperature was higher during the last few decades of the 20th
century than during any comparable period during the preceding four
centuries. This statement is justified by the consistency of the
evidence from a wide variety of geographically diverse proxies.
• Less confidence can be placed in large-scale surface temperature
reconstructions for the period from A.D. 900 to 1600. Presently
available proxy evidence indicates that temperatures at many, but not
all, individual locations were higher during the past 25 years than
during any period of comparable length since A.D. 900. The
uncertainties associated with reconstructing hemispheric mean or
global mean temperatures from these data increase substantially
backward in time through this period and are not yet fully
quantified.
• Very little confidence can be assigned to statements concerning the
hemispheric mean or global mean surface temperature prior to about
A.D. 900 because of sparse data coverage and because the
uncertainties associated with proxy data and the methods used to
analyze and combine them are larger than during more recent time
periods.
</quote?
and
The basic conclusion of Mann et al. (1998, 1999) was that the late
20th century warmth in the Northern Hemisphere was unprecedented
during at least the last 1,000 years. This conclusion has subsequently
been supported by an array of evidence that includes both additional
large-scale surface temperature reconstructions and pronounced changes
in a variety of local proxy indicators, such as melting on ice caps
and the retreat of glaciers around the world, which in many cases
appear to be unprecedented during at least the last 2,000 years. Not
all individual proxy records indicate that the recent warmth is
unprecedented, although a larger fraction of geographically diverse
sites experienced exceptional warmth during the late 20th century than
during any other extended period from A.D. 900 onward.
Based on the analyses presented in the original papers by Mann et al.
and this newer supporting evidence, the committee finds it plausible
that the Northern Hemisphere was warmer during the last few decades of
the 20th century than during any comparable period over the preceding
millennium. The substantial uncertainties currently present in the
quantitative assessment of large-scale surface temperature changes
prior to about A.D. 1600 lower our confidence in this conclusion
compared to the high level of confidence we place in the Little Ice
Age cooling and 20th century warming.
Even less confidence can be placed in the original conclusions by Mann
et al. (1999) that "the 1990s are likely the warmest decade, and 1998
the warmest year, in at least a millennium" because the uncertainties
inherent in temperature reconstructions for individual years and
decades are larger than those for longer time periods and because not
all of the available proxies record temperature information on such
short timescales.
</quote>
As far as prediction on sealevel, the fact is that the AR4 shows the
minimal sealevel increases without taking into consideration the far
more variable contributions. Sure, there may be many things we do NOT
know, however there are also many things we do know with significant
certainty.
Hope this helps clarify some of the misunderstandings related to
global warming, and the flawed accusations of fraudulent and/or faked
data as well as the findings on the Hockey Stick. Most of these
misunderstandings could have been trivially avoided by including
original sources and not rely on third hand sources.
On 2/4/07, Janice Matchett <janmatch@earthlink.net> wrote:
>
> At 02:11 PM 2/4/2007, PIM wrote:
>
> ... we see the following quote: <quote> If "global warming" is real and if
> man is responsible, why then do so many "experts" need to rely on obviously
> fraudulent data? The famous "hockey stick" graph showed the planet's
> climate history as basically one long bungalow with the Empire State
> Building tacked on the end. Completely false. </quote>
>
> 1. No fraudulent data
> @ False And "fraudulent" data is only the tip of the iceberg of the flawed
> data that is being relied upon. (see below)
>
>
> 2. No sole reliance on the hockey stick data ~ Pim
> @ Nor was there a claim of "sole reliance" on it, since other examples (out
> of many more that could have been noted) were given, as you well know.
> Tsk, tsk, tsk.
>
> "I don't trust ANYBODY's predictions on sea level. There are two many free
> variables most specifically how much anthropogenic CO2 there is going to be.
> The climate sensitivity numbers from the 2001 report have been confirmed by
> more recent research. We don't know how successful or unsuccessful we will
> be at controlling CO2 emissions or external factors such as possibly running
> out oil might have. We are discovering different negative (and positive!)
> feedback mechanisms that also affect the CO2 levels. Since 2001 we have
> better models where given the right inputs we can predict the effects but it
> is still GIGO (garbage in garbage out) because we still do not have accurate
> prediction of CO2 levels and probably never will." ~ Rich Blinne Mon, 11 Dec
> 2006 11:49:39 -0700
>
>
> 3. the hockey stick data, still seems correct I have rebutted these flawed
> arguments about the hockey stick in the past, so it is regrettable to see
> them repeated here uncritically. ~ Pim
> @ No kidding. Better tell the National Academy of Sciences - they must
> have overlooked your rebuttals. They don't believe the data "seems"
> correct, they "know" it is INcorrect. :) Where have you been for the last
> 7 months?
>
> NAS REPORT REAFFIRMS 'HOCKEY STICK' IS BROKEN
> ________________________________
> June 22, 2006
>
> "..today's congressionally commissioned review by the National Academy of
> Sciences.. shows that Dr. Michael Mann's "hockey stick" study was flawed,
> specifically refuting some of its most often-cited conclusions.
>
> The National Academy of Sciences' "Surface Temperature Reconstructions for
> the Last 2000 Years" noted in their summary that there were "relatively warm
> conditions centered around A.D. 1000 (identified by some as the 'Medieval
> Warm Period') and a relatively cold period (or 'Little Ice Age') centered
> around 1700." The hockey stick constructed by Mann and his colleagues
> purported to show temperatures in the Northern Hemisphere remained
> relatively stable over 900 years, then spiked upward in the 20th century.
>
> "Today's NAS report reaffirms what I have been saying all along, that
> Mann's 'hockey stick' is broken....Today's report refutes Mann's prior
> assertions that there was no Medieval Warm Period or Little Ice Age."
>
> The NAS report also stated that "substantial uncertainties" surround Mann's
> claims that the last few decades of the 20th century were the warmest in
> last 1000 years. In fact, while the report conceded that temperature data
> uncertainties increase going backward in time, it acknowledged that "not all
> individual proxy records indicate that the recent warmth is unprecedented…'
>
> In addition, the NAS report further chastises Mann, declaring "Even less
> confidence can be placed in the original conclusions by Mann et al. (1999)
> that 'the 1990's are likely the warmest decade, and 1998 the warmest year,
> in at least a millennium ...'"
>
> "This report shows that the planet warmed for about 200 years prior to the
> industrial age, when we were coming out of the depths of the Little Ice Age
> where harsh winters froze the Thames and caused untold deaths.
>
> "Trying to prove man-made global warming by comparing the well-known fact
> that today's temperatures are warmer than during the Little Ice Age is akin
> to comparing summer to winter to show a catastrophic temperature trend."
> http://epw.senate.gov/pressitem.cfm?id=257697&party=rep
>
>
> Now remember that Lindzen served on the NAS committee which validated the
> IPCC report and the Hockey stick data. ~ Pim
> @ See above. :)
>
> ~ Janice
>
>
>
>
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Received on Sun Feb 4 15:54:10 2007
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