Initially I wasn't going to respond to Joe's posting on the recetn NAS
report, but since I don't have anything better to do I figured what the
heck ...

As usual the newspapers get it wrong.

First the NAS report (available at http://www.nap.edu/catalog/11676.html
) does NOT say "The Earth is the hottest it has been in at least 400
years, probably even longer."

What it does say, at page 3 and again at page 109, is that it is
"plausible"  that it is the hottest it has been in the last millenium.
 In fact, the exact language is "Very little confidence can be assigned
to statements concerning hemispheric mean or global mean surface
temperature prior to about AD 900 because of sparce data coverage and
because uncertainties associated with proxy data and methods used to
analyze and combine them are larger than during more recent times."
 ....  "Based on the analyses presented in the original papers by Mann
et al. and this newer supporting evidence, the committe finds it
plausible that the Northern Hemisphere (which, by the way, is not the
whole globe - cd) 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. 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 for those for longer time periods, and
because not all of the available proxies record temerature information
on such short time scales."

Note also that they say the "last few decades of the 20th century" have
been the warmest in the last 400 years. OK, so when does this time
period actually begin? 1970?  Was there sufficient  human activity prior
to 1970 to trigger global warming the effects of which begin to show up
by 1970?  (By the way, data shows that the US was warmer during the
1930's than today.)

On page 23 the report does say "In particular, the numerous indications
that recent warmth is unprecedented for at least the last 400 years and
potentially the last several millenia, in combination with estimates of
external climate forcing variations over the same period, supports the
conclusion that human activities are responsible for much of the recent
warming. However, the uncertainties in the reconstruction of surface
temperature and external forcings for the period prior to the
instrumental record render the evidence less conclusive than other lines
of evidence cited above. It should also be noted that the scientific
consensus regarding human-induced global warming would not be
substantially altered if, for example, the global mean surface
temperature 1,000 years ago was found to be as warm as it is today."

This last bit is fascinating for several reasons 1) The report says
"plausible" and "potential" - the news article says "probably".  There
IS a big difference. 2) The idea that there is a scientific consensus is
just plain false. There is a large and credible segment of the
scientific community that still disputes anthropogenic global warming.
Whether they are right or wrong is irrelevant. If you have a significant
number of legitimate scientists debating the issue then there is no
consensus.  3)  The report says that even if it was warmer 1000 years
ago the GW adherents still will not change their minds. I think that
comes under the heading of "blind faith".

By the way, whatever happened to the Southern Hemisphere - don't they
count? The report talks only of the Northern Hemisphere. What if the
Southern Hemisphere is not warming???

Note also the deceptive way the article uses the data in the report.
 The article says "Climate scientists Michael Mann, Raymond Bradley and
Malcolm Hughes had concluded the Northern Hemisphere was the warmest it
has been in 2,000 years."  and "The National Academy scientists
concluded that the Mann-Bradley-Hughes research from the late 1990s was
"likely" to be true, said John "Mike" Wallace, an atmospheric sciences
professor at the University of Washington and a panel member."  The only
problem is that that  is NOT what the report says. The word "likely", in
this context, is taken from Mann's quote, not from the text of the
report or  the conclusion of the Committee.   See my reference above. At
no point does the Committee say that Mann is "likely" correct - just the
opposite.

The article goes on to say "The conclusions from the '90s research 'are
very close to being right"'and are supported by even more recent data,
Wallace said."  That is Wallace's opinion. Nowhere in the report does it
say, or even imply' that the 90's research "are very close to being right".

It also goes on to say "The scientists said they had less confidence in
the evidence of temperatures before 1600. But they considered it
reliable enough to conclude there were sharp spikes in carbon dioxide
and methane, the two major "greenhouse" gases blamed for trapping heat
in the atmosphere, beginning in the 20th century,after remaining fairly
level for 12,000 years."

The problems with this is that it totally mischaracterizes the report.
How do you translate the report's " 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. the 'the 1990s
..."  into "reliable enough".  At page 94 the report says ""Proxy
records are available for reconstructing claimte forcings over the last
2,000 years, but these climate forcing reconstructions are associated
with as much uncertainty as surface temperature reconstructions." That
qualifies as being "reliable enough"???

One main point of the whole report is that Mann's original work is not
trustworthy.  At page 107, in discussing McKitrick's criticism of Mann's
methodologies, the report says "Some of these criticisms are more
relevant than others, but taken together, they are an important aspect
of a more general finding of this committee, which is that uncertainties
of the published reconstructions (i.e. Mann's hockey stick - cd) have
been underestimated."  The uncertainties have been underestimated.

Second,  CO2 and methane are not "the major 'greenhouse' gases" as the
article asserts. The major "greenhouse gases" are aerosols - primarily
water vapor.

This one's a beaut. at page 95 --
"The primary natural greenhouse gases are carbon dioxide (CO2) and
methane (CH4), and nitrous oxide (N2)). Water vapor is also a grenhouse
gas that contributes the LARGEST WARMING (emphasis mine) but it is
treated as a feedback because its concentration is controlled by the
temperature of the atmosphere rather than by human activities."  Great,
so they admit that water vapor is the largest contributor to global
warming but they are going to ignore that because it is not man made.
Someone want to explain the sense of that to us?

Why  do people want to rely on newspaper articles (or movies by out of
work politicians) about scientific reports when they can easily read the
reports themselves and get better information?

'nuff said

Chuck Dolci

PS While the NAS is supposedly "a private organization" how much of
thier and their member's funding comes from the government.


Joe Fjelstad wrote:

>Earth's Temperature Is Hottest in Centuries
>Scientists Blame 'Human  Activities' for Warming Trend
>By JOHN HEILPRIN,  AP
>WASHINGTON (June 22) -- The Earth is the hottest it has  been in at least 400
>years, probably even longer. The National Academy of  Sciences, reaching that
>conclusion in a broad review of scientific work  requested by Congress,
>reported Thursday that the "recent warmth is  unprecedented for at least the last
>400 years and potentially the last several  millennia."
>A panel of top climate scientists told lawmakers that the  Earth is heating
>up and that "human activities are responsible for much of the  recent warming."
>Their 155-page report said average global surface temperatures  in the
>Northern Hemisphere rose about 1 degree during the 20th century.
>This is shown in boreholes, retreating glaciers and other  evidence found in
>nature, said Gerald North, a geosciences professor at Texas  A&M University
>who chaired the academy's panel.
>The report was requested in November by the chairman of the  House Science
>Committee, Rep. Sherwood Boehlert, R-N.Y., to address naysayers  who question
>whether global warming is a major threat.
>Last year, when the House Energy and Commerce Committee  chairman, Rep. Joe
>Barton, R-Texas, launched an investigation of three climate  scientists,
>Boehlert said Barton should try to learn from scientists, not  intimidate them.
>Boehlert said Thursday the report shows the value of having  scientists
>advise Congress.
>"There is nothing in this report that should raise any  doubts about the
>broad scientific consensus on global climate change," he  said.
>Other new research Thursday showed that global warming  produced about half
>of the extra hurricane-fueled warmth in the North Atlantic  in 2005, and
>natural cycles were a minor factor, according to Kevin Trenberth  and Dennis Shea of
>the Commerce Department's National Center for Atmospheric  Research. Their
>study is being published by the American Geophysical Union.
>The Bush administration has maintained that the threat is  not severe enough
>to warrant new pollution controls that the White House says  would have cost 5
>million Americans their jobs.
>Climate scientists Michael Mann, Raymond Bradley and  Malcolm Hughes had
>concluded the Northern Hemisphere was the warmest it has been  in 2,000 years.
>Their research was known as the "hockey-stick" graphic because  it compared the
>sharp curve of the hockey blade to the recent uptick in  temperatures and the
>stick's long shaft to centuries of previous climate  stability.
>The National Academy scientists concluded that the  Mann-Bradley-Hughes
>research from the late 1990s was "likely" to be true, said  John "Mike" Wallace, an
>atmospheric sciences professor at the University of  Washington and a panel
>member. The conclusions from the '90s research "are very close to being right"
>and are supported by even more recent data, Wallace  said.
>The panel looked at how other scientists reconstructed the  Earth's
>temperatures going back thousands of years, before there was data from  modern
>scientific instruments.
>For all but the most recent 150 years, the academy  scientists relied on
>"proxy" evidence from tree rings, corals, glaciers and ice  cores, cave deposits,
>ocean and lake sediments, boreholes and other sources.  They also examined
>indirect records such as paintings of glaciers in the  Alps.
>Combining that information gave the panel "a high level of  confidence that
>the last few decades of the 20th century were warmer than any  comparable
>period in the last 400 years," the academy said.
>Overall, the panel agreed that the warming in the last few  decades of the
>20th century was unprecedented over the last 1,000 years, though  relatively
>warm conditions persisted around the year 1000, followed by a "Little  Ice Age"
>from about 1500 to 1850.
>The scientists said they had less confidence in the  evidence of temperatures
>before 1600. But they considered it reliable enough to  conclude there were
>sharp spikes in carbon dioxide and methane, the two major  "greenhouse" gases
>blamed for trapping heat in the atmosphere, beginning in the  20th century,
>after remaining fairly level for 12,000 years.
>Between 1 A.D. and 1850, volcanic eruptions and solar  fluctuations were the
>main causes of changes in greenhouse gas levels. But those  temperature
>changes "were much less pronounced than the warming due to  greenhouse gas" levels
>by pollution since the mid-19th century, it said.
>The National Academy of Sciences is a private organization  chartered by
>Congress to advise the government of scientific matters.
>06/22/06 12:40 EDT
>
>
>