from: Mike Hulme <m.hulmeatXYZxyz.ac.uk>
subject: heat over Medieval warmth
Not much validity. See the comments below from two very senior figures in the field, Keith
Briffa here at UEA and Tom Crowley at Duke University in the States.
The Soon/Baliunas/Idso/Idso/Legates paper is another contrived piece of hubris from
convicted sceptics. There are no new data here that undermine the IPCC considered
From Keith Briffa ....
sorry to have been somewhat silent recently . I am now back at work after my operation and
eager to state that what Tom says here is right on the nail.
I believe passionately that we have a long way to go to get realistic and accurate
(absolute) measures of Hemispheric temperatures over the last millennium and earlier .
However, we must not lose sight of the fact that the "best evidence" is certainly in
support of unprecedented (truly mean Hemispheric and annual) warming in the 20th century
and recent decades. The modern (instrumental) indications of Hemispheric warmth are (almost
literally) incomparably superior to those based on our high-resolution proxy records (with
their narrow coverage and largely summer seasonal bias) . Even pushing the few individual
records to their maximum warmth limit , the most sensible interpretation of the data does
not provide much of a case for equivalent warmth in any "Medeival" period (or on any
timescale). Those who prefer to believe in a globally warmer Medieval period largely fall
back on poorly resolved , even more selective evidence that has real problems e.g.
interpretable signal (temp. versus precip.) ; qualitative measurement ; non-deconvolved
lagged responses, and geographical bias that is at least as poor as our high-resolution
data. The science is not progressed without overcoming these problems. Our own desire to
recognize and address the limitations of our own data in the search for accurate and
absolute climate histories should not be confused with a clear expression that "as we
stand" the evidence against unprecedented recent warming does not carry the day.
At 09:57 AM 4/4/03 -0500, Tom Crowley wrote:
Keith, forgot to cc you on this, Tom
Date: Fri, 4 Apr 2003 09:56:40 -0500
To: Simon Tett <simon.tettatXYZxyzoffice.com>
From: Tom Crowley <tcrowleyatXYZxyze.edu>
Subject: Re: [firstname.lastname@example.org: PRESS: 20th century is neither the warmest century
nor the centur y with the most extreme weather of the past 1000 years]
Cc: "Jenkins, Geoff" <geoff.jenkinsatXYZxyzoffice.com>, "Parker, Dave"
<deparkeratXYZxyzoffice.com>, "Tett, Simon" <sfbtettatXYZxyzoffice.com>, "Folland, Chris"
<chris.follandatXYZxyzoffice.com>, "Stott, Peter" <pastottatXYZxyzoffice.com>, "Jones, Gareth"
along with others I was contacted by a New York Times reporter on the Soon and Baliunas
paper - I know that Phil is chagrined by the Soon and Baliunas paper. Some of us are
thinking about writing some type of rebuttal. at least three main problems in that paper
1) they show no data - only report what others state (sort of a pseudo-Bayesian expert
2) they report various multi-decadal warmings from different places, totally ignoring that
they occur at different times - this was the point I made earlier in a paper I wrote in
Ambio (others too have made the same point).
3) the reporting is suspect - in the description of my ambio paper they state that the data
coverage was worldwide - it was not - all the data points were from the mid-high latitudes
northern hemisphere, but the composite was compared against the northern hemisphere
They also state that I conclude that there was no Medieval Warm Period. Yet the title of my
paper was "How warm was the Medieval Warm Period?" I do state that there was such a thing
as a period in the Middle Ages warmer than the Little Ice Age - just that peak composite
warming was no greater than the mid-20th century warming.
the reason that Soon and Baliunas have gotten a lot of attention about this is that the
conservative publicity machine in the U.S. has contacts in high places - the rest of us
could write the most eloquent, rigorous rebuttal and proof in the world and it would at
best wind up in the trash bin of some Congressional committee.
At 15:38 07/04/2003 +0100, you wrote:
Mike - did you see this? has it any validity?
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Date sent: Mon, 07 Apr 2003 12:59:32 -0700
From: "Dr. Dennis Bray" <Dennis.BrayatXYZxyzs.de>
Subject: climate change wrong again
To: Simon.Shackley@umist.ac.uk, Hans.von.Storch@gkss.de,
Thought this might be of interest
Middle Ages were warmer than today, say scientists
By Robert Matthews, Science Correspondent
Claims that man-made pollution is causing "unprecedented" global warming
have been seriously undermined by new research which shows that the
Earth was warmer during the Middle Ages.
>From the outset of the global warming debate in the late 1980s,
environmentalists have said that temperatures are rising higher and
faster than ever before, leading some scientists to conclude that
greenhouse gases from cars and power stations are causing these
"record-breaking" global temperatures.
Last year, scientists working for the UK Climate Impacts Programme said
that global temperatures were "the hottest since records began" and
added: "We are pretty sure that climate change due to human activity is
here and it's accelerating."
This announcement followed research published in 1998, when scientists
at the Climatic Research Unit at the University of East Anglia declared
that the 1990s had been hotter than any other period for 1,000 years.
Such claims have now been sharply contradicted by the most comprehensive
study yet of global temperature over the past 1,000 years. A review of
more than 240 scientific studies has shown that today's temperatures are
neither the warmest over the past millennium, nor are they producing the
most extreme weather - in stark contrast to the claims of the
The review, carried out by a team from Harvard University, examined the
findings of studies of so-called "temperature proxies" such as tree
rings, ice cores and historical accounts which allow scientists to
estimate temperatures prevailing at sites around the world.
The findings prove that the world experienced a Medieval Warm Period
between the ninth and 14th centuries with global temperatures
significantly higher even than today.
They also confirm claims that a Little Ice Age set in around 1300,
during which the world cooled dramatically. Since 1900, the world has
begun to warm up again - but has still to reach the balmy temperatures
of the Middle Ages.
The timing of the end of the Little Ice Age is especially significant,
as it implies that the records used by climate scientists date from a
time when the Earth was relatively cold, thereby exaggerating the
significance of today's temperature rise.
According to the researchers, the evidence confirms suspicions that
today's "unprecedented" temperatures are simply the result of examining
temperature change over too short a period of time.
The study, about to be published in the journal Energy and Environment,
has been welcomed by sceptics of global warming, who say it puts the
claims of environmentalists in proper context. Until now, suggestions
that the Middle Ages were as warm as the 21st century had been largely
anecdotal and were often challenged by believers in man-made global
Dr Philip Stott, the professor emeritus of bio-geography at the
University of London, told The Telegraph: "What has been forgotten in
all the discussion about global warming is a proper sense of history."
According to Prof Stott, the evidence also undermines doom-laden
predictions about the effect of higher global temperatures. "During the
Medieval Warm Period, the world was warmer even than today, and history
shows that it was a wonderful period of plenty for everyone."
In contrast, said Prof Stott, severe famines and economic collapse
followed the onset of the Little Ice Age around 1300. He said: "When the
temperature started to drop, harvests failed and England's vine industry
died. It makes one wonder why there is so much fear of warmth."
The United Nation's Intergovernmental Panel on Climate Change (IPCC),
the official voice of global warming research, has conceded the
possibility that today's "record-breaking" temperatures may be at least
partly caused by the Earth recovering from a relatively cold period in
recent history. While the evidence for entirely natural changes in the
Earth's temperature continues to grow, its causes still remain
Dr Simon Brown, the climate extremes research manager at the
Meteorological Office at Bracknell, said that the present consensus
among scientists on the IPCC was that the Medieval Warm Period could not
be used to judge the significance of existing warming.
Dr Brown said: "The conclusion that 20th century warming is not unusual
relies on the assertion that the Medieval Warm Period was a global
phenomenon. This is not the conclusion of IPCC."
He added that there were also doubts about the reliability of
temperature proxies such as tree rings: "They are not able to capture
the recent warming of the last 50 years," he said.
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