From: Phil Jones <p.jones@uea.ac.uk>
To: Kevin Trenberth <trenbert@ucar.edu>
Subject: Re: 
Date: Wed Aug 10 17:13:37 2005

   Fine with me. Let's hope they agree by tomorrow.
    Phil
   At 17:11 10/08/2005, you wrote:

     Ok so here is how it now reads:
     The temperature increases are consistent with the observed nearly worldwide reduction in
     glacier and ice cap mass and extent in the 20^th century. Tropical glacier changes in
     South America and Africa, and those in Tibet are synchronous with higher latitude ones,
     and all have shown declines in recent decades. Local temperature records all show a
     slight warming, but not of the magnitude required to explain the rapid reduction in mass
     of such glaciers (e.g., on Kilimanjaro). Glaciers and ice caps respond not only to
     temperatures but also changes in precipitation, and both global mean winter accumulation
     and summer melting have increased over the last half century in association with
     temperature increases.  Other factors in recent ablation include changes in cloudiness
     and water vapour and associated radiation, and surface sensible heat exchange.
     Precipitation anomalies are also important before 1900 in glacier fluctuations. In some
     regions moderately increased accumulation observed in recent decades is consistent with
     changes in atmospheric circulation and associated increases in winter precipitation
     (e.g., southwestern Norway, parts of coastal Alaska, Patagonia, Karakoram, and Fjordland
     of the South Island of New Zealand) even as enhanced ablation has led to marked declines
     in mass balances in Alaska and Patagonia.
     Kevin
     Phil Jones wrote:

      Sort of arguing that way. It is also the before 1900 part. Precip and temp anomalies
      are important at all times for glaciers. Their influence didn't change around 1900.
      So what about Precipitation anomalies are also important before 1900.
      I'd not got the implication. Adding also makes it clearer.
      Phil
     At 16:56 10/08/2005, Kevin Trenberth wrote:

     Phil is arguing for changes to 4.5.  Maybe the statement is too strong although it is
     consistent with the last para of 4.5.2.? An alternative might be:  Precipitation
     anomalies are important before 1900.  In the context this implies in addition to
     temperature.
     Kevin
     Phil Jones wrote:

      Georg,
         I've now also looked at the figures you sent from Ch 4. Kevin has the sentence,
      which Peter may have added? I reckon this is too strong. Can we omit it?
      Sentence is
     Before 1900, glacier fluctuations probably mainly reflect precipitation anomalies.
       Reasoning
      Is this a general statement. I wonder if we need it. Oerlemans uses estimated
      glacier termini positions (and related ELA changes) to infer past temperatures
      and you have his figure. I know he assumes precip to have remained essentially
      the same but he backs out temperature.  Also glaciers in Europe advanced
      in the 17th and 18th centuries. It was cooler then (more so in winter than
      summer). I also have a paper resubmitted to JGR where Alpine precip shows
      no long-term changes since 1800. This uses loads of stations and is from the
      ALP-IMP project that ZAMG co-ordinate (Reinhard Boehm).
      So the advances are caused by more precip, but the retreats by higher summer T
      and maybe less winter precip.

      Cheers
      Phil
     At 16:23 10/08/2005, Kevin Trenberth wrote:

     Hi Georg
     Many thanks for the attachments.  I had looked at the ZOD but this is much more
     informative.  Based on your comments and the 4.5 section I have come up with the
     following bullet.  Note that here we are writing for a general audience.  I have now
     tried to include more clearly the factors involved.  I think these are consistent with
     your chapter but the language in your chapter might be improved in a couple of places.
     For instance an important forcing is radiation (solar and IR) which are greatly impacted
     by clouds, water vapor, and albedo (the dirty cover on top of snow Phil referred to),
     and I thought these could be brought out better in your chapter.  These are perhaps more
     basic that temperature lapse rates and precipitation gradients which are consequences.
     In 4.5.2 you use the term "radiatively forced" but it is not clear what that means.  I
     suggest using some of these terms.  Also it is not clear what "amplified hydrological
     cycle" means.  [FYI, the expectation is for more intense precipitation, not necessarily
     for more total (owing to pollution effects).  The former is determined by increased
     water vapor].  I took some of your words in the following.  We need to emphasize that
     glaciers are not just high latitudes. I retained Kilimanjaro as that has received a lot
     of publicity. Some of this is necessarily abrupt, but there will be a reference to 4.5
     immediately following this bullet.  So the recent reversals in NZ and Norway can not be
     dealt with here.
     Let me know if you have further suggestions.  Again, many thanks
     Regards
     Kevin
     o The temperature increases are consistent with the observed nearly worldwide reduction
     in glacier and ice cap mass and extent in the 20^th century. Tropical glacier changes in
     South America and Africa, and those in Tibet are synchronous with higher latitude ones,
     and all have shown declines in recent decades. Local temperature records all show a
     slight warming, but not of the magnitude required to explain the rapid reduction in mass
     of such glaciers (e.g., on Kilimanjaro). Glaciers and ice caps respond not only to
     temperatures but also changes in precipitation, and both global mean winter accumulation
     and summer melting have increased over the last half century in association with
     temperature increases.  Other factors in recent ablation include changes in cloudiness
     and water vapour and associated radiation, and surface sensible heat exchange. Before
     1900, glacier fluctuations probably mainly reflect precipitation anomalies. In some
     regions moderately increased accumulation observed in recent decades is consistent with
     changes in atmospheric circulation and associated increases in winter precipitation
     (e.g., southwestern Norway, parts of coastal Alaska, Patagonia, Karakoram, and Fjordland
     of the South Island of New Zealand) even as enhanced ablation has led to marked declines
     in mass balances in Alaska and Patagonia.
     Georg Kaser wrote:

     Kevin,
     Have many thanks for compiling and editing 3.9. I agree that the "radiatively forced"
     and the "amplified hydrological cycle" should be removed and I also agree with Phil's
     comment on the "local heat budget". In glaciology, the sum of each energy flux toward
     and from the respective snow/ice surface is considered to make up the "local heat
     budget". This also includes the sensible heat flux.
     There are some other points in the text which I would like to comment:
     1. Tropical glaciers are considered those in the South American Andes between Venezuela
     and Norhern Boliva, those in East Africa and those in Irian Jaya (New Guinea). In
     Chapter 4, Tibetean glaiers are taken as part of the Asian High Mountains (find the
     present state Chapter 4.5. "Glaciers and Ice Caps attached).
     2. Alaska, Patagonia, Karakoram, Norway and NZ cannot be merged in the respective
     statement. In Alaska and Patagonia, moderately increase accumulation is accompanied by
     strongly enhanced ablation making the mass balances markedly negative. From
     glaciological site, no studies concerning atmospheric circulation patterns are provided
     in the respective studies.
     In the Karakoram mountains, enhanced accumulation has led to considerable glacier
     advances, increased winter accumulation from the Westerlies is only suggested but not
     subject of detailed studies. Heavy debris loads on the tongues probably prevent from
     enhanced abaltion.
     In Southwest Norway and NZ South Island, glaciers advances have ceded around 2000. I
     don't know whether their advances shall still be mentioned in extension; I would not do
     so beyond the respective statement in Ch. 4.5.
     3. "If continued, some may disappear within the next 30 years." This sentence can stand
     for every mountain region in the world and should not be used for tropical mountains
     only. Everywhere, many small glaciers have disappeared since the 19th Century maxima and
     many will disappear soon in the Alps, the Caucasus, in the Asian High mountains etc. as
     well as in the Tropics. From the today's perspective Mount Kenya, all Mountains in the
     Rwenzori Range except Mt. Stanley, Irain Jaya will be without glaciers soon, probably
     sooner than Kilimanjaro; well known and studied glaciers in the Andes like Chacaltaya,
     Charquini and Pastoruri will also disappear soon. This is not because of a particular
     regional climate feature but just because they were already small when retreats started.
     As you will see from Figure 4.5.5. Kilimanjaro's plateau ice is particular, slope
     glaciers are less. The plateau glaciers retreat from their vertical walls where no
     accumulation is possible and since they do so, there is no way to find an equilibrium
     besides disappearance. The vertical walls are a result of cold temperatures high
     sublimation and strong solar radiance. There is no way to replace the retreat by ice
     dynamics on the flat summit plateau. Slope glaciers are only partially subject of this
     kind of ablation and their retreat rate seems to have slowed markedly (See insert of Fig
     4.5.5). If Kilimanjaro is mentioned in 3.9. it must also be added that it is a
     particular case with complex relation to climate change.
     4. All studies which investigate tropical glacier retreat and climate show the dominance
     of changes in energy and mass balance terms which are related to the atmospheric
     moisture content rather than locally measured air temperatures. Both increased and
     reduced moisture can lead to negative mass balances and it has done so in most cases
     studied (Cordillera Blanca, Peru, Cordillera Real, Bolivia, Antisana, Ecuador, Rwenzori,
     Mt. Kenia, Kilimanjaro). Yet, wherever respective analyses were made, correlations were
     found to anomalies in ENSO or Indian Oceans Indian Ocean Dipole Mode respectively
     strongly indicating global warming as the principle reason of th eretreat.
     I give you this lengthy explanation in order to make sure that the very compressed and
     condensed bullet in 3.9. gets the right content. I have started to change your paragraph
     suggestion accordingly but have to admit that, not being a native speaker myself, it
     either becomes very long or very awkward.
     I also appreciate Phil's statement about Quelccaya and Sajama. Doug Hardy and Ray
     Bradley run AWS' there since a couple of years as well as on Kilimanjaro with all the
     problems of recording data at such high elevation sites. Doug is preparing a paper on
     the climate records there but it has still not reached it's final state.
     Information on sublimation on Quelccaya is not published such as the positive mass
     balances and advances on several Andean glaciers between 1998 and 2002 are not
     published. Kilimanjaro has experienced both ablation as well as accumulation layers on
     the horizontal surfaces over the last years. I have just come back from fieldwork there
     last week and the last half year was a mass loss year. Being very much involved into
     tropical glaciers myself, I have to accept that such detailed information would be
     available for several hundreds of glaciers in the world each one providing 10 or more
     publications. Going into such details cannot be the aim of the report, I am afraid.
     Best wishes,
     Georg
     Georg Kaser
     -------------------------------------------------
     Institut fuer Geographie
     Innrain 52
     A-6020 INNSBRUCK
     Tel: ++43 512 507 5407
     Fax: ++43 512 507 2895
     [1]http://meteo9.uibk.ac.at/IceClim/CRYO/cryo_a.html

--
****************
Kevin E.
Trenberth
        e-mail:
[2]trenbert@ucar.edu
Climate Analysis Section,
NCAR
        [3]www.cgd.ucar.edu/cas/
P. O. Box
3000,
        (303) 497
1318
Boulder, CO
80307
        (303) 497
1333 (fax)

Street address: 1850 Table Mesa Drive, Boulder, CO  80303


     Prof. Phil Jones
     Climatic Research Unit        Telephone +44 (0) 1603 592090
     School of Environmental Sciences    Fax +44 (0) 1603 507784
     University of East Anglia
     Norwich                          Email    [4]p.jones@uea.ac.uk
     NR4 7TJ
     UK
     ----------------------------------------------------------------------------


--
****************
Kevin E.
Trenberth
        e-mail:
[5]trenbert@ucar.edu
Climate Analysis Section,
NCAR
        [6]www.cgd.ucar.edu/cas/
P. O. Box
3000,
        (303) 497 1318
Boulder, CO
80307
        (303) 497 1333 (fax)

Street address: 1850 Table Mesa Drive, Boulder, CO  80303

     Prof. Phil Jones
     Climatic Research Unit        Telephone +44 (0) 1603 592090
     School of Environmental Sciences    Fax +44 (0) 1603 507784
     University of East Anglia
     Norwich                          Email    [7]p.jones@uea.ac.uk
     NR4 7TJ
     UK
     ----------------------------------------------------------------------------


--
****************
Kevin E. Trenberth                              e-mail: [8]trenbert@ucar.edu
Climate Analysis Section, NCAR                  [9]www.cgd.ucar.edu/cas/
P. O. Box 3000,                                 (303) 497 1318
Boulder, CO 80307                               (303) 497 1333 (fax)

Street address: 1850 Table Mesa Drive, Boulder, CO  80303

   Prof. Phil Jones
   Climatic Research Unit        Telephone +44 (0) 1603 592090
   School of Environmental Sciences    Fax +44 (0) 1603 507784
   University of East Anglia
   Norwich                          Email    p.jones@uea.ac.uk
   NR4 7TJ
   UK
   ----------------------------------------------------------------------------

References

   1. http://meteo9.uibk.ac.at/IceClim/CRYO/cryo_a.html
   2. mailto:trenbert@ucar.edu
   3. http://www.cgd.ucar.edu/cas/
   4. mailto:p.jones@uea.ac.uk
   5. mailto:trenbert@ucar.edu
   6. http://www.cgd.ucar.edu/cas/
   7. mailto:p.jones@uea.ac.uk
   8. mailto:trenbert@ucar.edu
   9. http://www.cgd.ucar.edu/cas/

