date: Tue Apr  8 09:53:03 2003
from: Mike Hulme <m.hulme@uea.ac.uk>
subject: heat over Medieval warmth
to: simon.shackley@umist.ac.uk

   Simon,
   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
   judgement.
   Mike
   ______________________________________
   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.tett@metoffice.com>
   From: Tom Crowley <tcrowley@duke.edu>
   Subject: Re: [simon.brown@metoffice.com: 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.jenkins@metoffice.com>, "Parker, Dave"
   <deparker@metoffice.com>, "Tett, Simon" <sfbtett@metoffice.com>, "Folland, Chris"
   <chris.folland@metoffice.com>, "Stott, Peter" <pastott@metoffice.com>, "Jones, Gareth"
   <gsjones@metoffice.com>
   Bcc: pnl_group.all
   X-Attachments:
   Simon,
   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
   are:
   1) they show no data - only report what others state (sort of a pseudo-Bayesian expert
   assessment).
   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
   instrumental record.
   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.
   Regards, Tom
   At 15:38 07/04/2003 +0100, you wrote:

     Mike - did you see this?  has it any validity?
     Simon
     ------- Forwarded message follows -------
     Date sent:              Mon, 07 Apr 2003 12:59:32 -0700
     From:                   "Dr.  Dennis Bray" <Dennis.Bray@gkss.de>
     Subject:                climate change wrong again
     To:                     Simon.Shackley@umist.ac.uk, Hans.von.Storch@gkss.de,
     Eduardo.Zorita@gkss.de
     Thought this might be of interest
     D

      Daily Telegraph


     Middle Ages were warmer than today, say scientists
     By Robert Matthews, Science Correspondent
     (Filed: 06/04/2003)
     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
     environmentalists.
     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
     warming.
     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
     mysterious.
     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.
      4 April 2003: English strawberries on shelves in record time
      20 February 2003: Britain faces drier summers and flooding
      4 February 2003: Climate change plagues hay fever sufferers
      30 November 2002: Growth in flights will wreck climate, says commission
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        External links

      UK Climate Impacts Program

      Climatic Research Unit - University of East Anglia

      Intergovernmental Panel on Climate Change - United Nations





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