Tuesday, May 8, 2012

3966.txt

cc: "Keith Briffa,cru (Climatic Research Unit)" <K.BriffaatXYZxyz.ac.uk>, Peter Lemke <plemkeatXYZxyz-bremerhaven.de>
date: Mon, 14 Aug 2006 16:19:54 +0200 (MEST)
from: Georg Kaser <Georg.KaseratXYZxyzk.ac.at>
subject: Re: Oerlemans in IPCC
to: olgasolomina <olgasolominaatXYZxyzdex.ru>

<x-flowed>
Dear Olga and Keith,

have many thanks for the cross check. As for the paragraphs cited from
Chapetr 4, only slight changes have been made that do not affect the
content (see attached Chapter4). The Oerlemans regions have been named in
the Figure 4.5.1 caption.

Also the Oerlemans paragraph in Chapter 6 is fine and I hope you can keep
it as it is.

As for the paragraph on the Tropical isotop analyses the first part is
fine, the second one contradicts the respective Chapter 4:

You state:

"Very rapid and apparently unprecedented melting of tropical ice caps has
been observed in recent decades (Thompson et al., 2000; Thompson, 2001)
(see Box 6.3), likely associated with enhanced warming at high elevations
(Gaffen et al., 2000), but other factors besides temperature can strongly
influence tropical glacier mass balance (see Chapter 4)."

We show that the shrinkage of Tropical glaciers has the same time pattern
and the same magnitude as the shrinkage of glaciers in the mid
latitudes since the "Littel Ice Age". They melt not more rapid than
comparable glaciers somewhere else and not in an unprecented way (e.g.
shrinkage rates have been stronger in the 1940s).

There is only one exception: Kilimanjaro plateau. There, glacier shrinkage
is NOT due to 20th century climate change. (see respective paragraph in
the attached Chapter 4 draft). I also attach the respective Kilimanjaro
paper that went into press in order to make the TSU deadline in July.

If you refer to the Quelccaya Ice Cap, make clear that you talk about
that only and that it was reported that meltwater had penetrated the
ice where it was still "dry" in the 1970s. One cannot deviate general
"Very rapid and apparently unprecedented melting of tropical ice caps in
recent decades" from this.

Best wishes,
Georg

Georg Kaser
-------------------------------------------------
Institut fuer Geographie
Innrain 52
A-6020 INNSBRUCK
AUSTRIA
Tel: ++43 512 507 5407
Fax: ++43 512 507 2895
http://meteo9.uibk.ac.at/IceClim/CRYO/cryo_a.html

On Mon, 14 Aug 2006, olgasolomina wrote:

> Dear Georg and Keith,
>
>
> We discuss Oerleman?s paper two times ? in Ch 6 and Ch 4. I copied here the sections from both chapters. I guess you have to decide what to keep and where. I also copied a paragraph from ch6 concerning the glacier retreat ? Georg might be interested to see it.
> We decided to write ?Little Ice Age? and ?Medieval Warm Period? in quotes. Shall we correct it now? This should be consistent though the whole Assessment ? we probably have to draw attention of TSU to this point.
>
> Cheers,
> olga
>
>
> From SOD ch 4
>
> 4-14-2-12
>
> 4.5.2. Large and Global Scale Analyses
>
> Records of glacier length changes go far back in time (written reports as far back as 1600 in a few cases) and are directly related to low-frequency climate change. From 169 glacier-length records, Oerlemans (2005) has compiled mean length variations of glacier tongues for large scale regions from 1700 to 2000 (Figure 4.5.1). Although much local to regional and high-frequency variability is superimposed, the smoothed series give an apparently homogeneous signal. General retreat of glacier termini started after 1800, with considerable mean retreat rates in all regions after 1850 lasting throughout the 20th century. A slowdown of retreats between about 1970 and 1990 is more evident in the raw data. Retreats were again generally rapid in the 1990s; the Atlantic and the Southern Hemisphere curves reflect precipitation driven advances of glaciers in Western Scandinavia and New Zealand (Chinn et al., 2005).
>
> 4-18-32-41
>
> The surface mass balance of snow and ice is determined by a complex interaction of energy fluxes toward and away from the surface, and the occurrence of solid precipitation. Nevertheless, glacier fluctuations show a strong statistical correlation with air temperature at least on a large spatial scale throughout the 20th century (Greene, 2005), and a strong physical basis exists to explain why warming would cause mass loss. Changes in snow accumulation also matter, and may dominate in response to strong circulation changes or when temperature is not changing greatly. For example, analyses of glacier mass balances, volume changes, length variations and homogenized temperature records for the western portion of the European Alps (Vincent et al., 2005) clearly indicate the role of precipitation changes in glacier variations in the 18th and 19th centuries. Similarly, Nesje and Dahl (2003) explained glacier advances in southern Norway in the early 18th century based on increased!
w!
> inter precipitation rather than cold temperatures.
>
>
> FROM TOD ch 6
> 6-30-43-55
>
> Oerlemans (2005) constructed a temperature history for the globe based on
169 glacier-length records. He used simplified glacier dynamics that
incorporate specific response time and climate sensitivity estimates for each
glacier. The reconstruction suggests that moderate global warming occurred
after the middle of the 19th century, with about 0.6?C warming by the middle
of the 20th century. Following a 25-year cooling, temperatures rose again
after 1970, though much regional and high-frequency variability is
superimposed on this overall interpretation. However, this approach does not
allow for changing glacier sensitivity over time, which may limit the
information before 1900. For example, analyses of glacier mass balances,
volume changes, and length variations along with temperature records in the
western European Alps (Vincent et al., 2005) indicate that between 1760 and
1830, glacier advance was driven by precipitation that was 25% above the 20th
century average, while there was little difference in average temperatures.
Glacier retreat after 1830 was related to reduced winter precipitation and
the influence of summer warming only became effective at the beginning of the
20th century. In southern Norway, early 18th century glacier advances can be
attributed to increased winter precipitation rather than cold temperatures
(Nesje and Dahl, 2003).
>
>
> I also copy here a paragraph from ch 6 that you might want to take into account.
>
> FROM TOD ch 6
> 6-32-40-48
>
> Stable isotope data from high-elevation ice cores provide long records and have been interpreted in terms of past temperature variability (Thompson, 2000), but recent calibration and modelling studies, in South America and southern Tibet (Hoffmann et al., 2003; Vuille and Werner, 2005; Vuille et al., 2005), indicate a dominant sensitivity to precipitation changes, at least on seasonal to decadal timescales, in these regions. Very rapid and apparently unprecedented melting of tropical ice caps has been observed in recent decades (Thompson et al., 2000; Thompson, 2001) (see Box 6.3), likely associated with enhanced warming at high elevations (Gaffen et al., 2000), but other factors besides temperature can strongly influence tropical glacier mass balance (see Chapter 4).
>
>
>
>
>
> --
> Dr.Olga Solomina
> Corresponding Member of Russian Academy of Sciences
> Institute of Geography RAS
> Staromonetny-29
> Moscow, Russia
> tel: 007-095-125-90-11, 007-095-939-01-21
> fax: 007-095-959-00-33
> e-mail: olgasolominaatXYZxyzdex.ru
> PAGES Web:www.pages-igbp.org
>
> --
> ??????? ??????? ????, ????? ??????? ????? ?? ??????? http://mail.yandex.ru
>
>
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