Jökull - 01.10.1998, Side 33

Years
stress glaciers (cirque glaciers, glaciers réservoirs)
reflect yearly changes in climate and mass balance al-
most without any delay.”
2. “Larger, dynamic, high-stress glaciers (moun-
tain glaciers, glaciers évacuateurs, react dynamically
to decadal variations in climatic and mass balance
forcing with an enhanced amplitude after a delay of
several years.”
3. “The largest valley glaciers give strong and
most efficiently smoothed signals of secular trends
with a delay of several decades.”
The figure, therefore, mixes category 2 and cate-
gory 3 glaciers to some extent, which is unfortunate,
but a further subdivision of the glaciers is not war-
ranted due to the small number of glaciers in the data
set, and we have not been able to discern a difference
in the response of the glaciers according to size in this
small data set.
Figure 4 shows that between 80 and 90% of the
termini were retreating in the time period 1931 to
Fig. 4. Percentage of advancing (dense shading) and retreat-
ing (less dense shading) termini of non-surging glaciers in
Iceland as a function of time from 1930/31 to 1994/95. No
shading indicates stationary termini. Over most of the time
period shown, the figure is based on measurements at 15 to
19 locations at 18 termini (somewhat fewer termini in the
years 1931 to 1935). The figure is based on the measure-
ments of glacier variations in Iceland tabulated in Table 2 in
Sigurðsson (this volume). The glaciers represented in the
figure are listed in the text.
-Hlutfall jökla sem gangafram (þéttstrikað) og hopa (gisin
strikun) á árabilinu 1930131 til 1994/95. Ostrikað að svæði
táknar hlutfall kyrrstœðra jökulsporða. Einungis eru teknir
með jöklar sem ekki eru framhlaupsjöklar. Yfir mestan hluta
tímabilsins er myndin byggð á gögnum frá 15 til 19
jökulsporðum (heldur færri á árunum 1931 til 1935). Nöfn
jöklanna komafram í meginmáli. Gögnin sem myndin byggir
á koma fram í töflu 2 í grein Odds Sigurðssonar um
jöklabreytingar á Islandi í þessu tölublaði Jökuls.
1960. Although between 10 and 20% of the glacier
termini were typically advancing each year during
this period, all the termini, without exception, had re-
treated from their 1930 positions by 1960. After 1960,
the fraction of advancing termini started to rise, but
after 1980 more glaciers have started retreating again.
The fluctuations of the Icelandic glaciers are similar
to glacier fluctuations in the Alps (Haeberli and oth-
ers, 1989; Haeberli, 1995), but glacier fluctuations
from other parts of the world can be quite different.
For example, the retreat rate of glaciers in the Tian-
shan Mountains in China did not slow down or re-
a Years þ Years
Fig. 5. Summer temperature (average of May to September) and annual precipitation (sum from October of previous year to
September) at Kirkjubæjarklaustur (a) and Reykjavík (b) from 1931 to 1995 (solid curves). Dashed curves are weighted, run-
ning 5 year means using the weights (1/9,2/9,3/9,2/9,1/9) centered about each year.
- Sumarhiti (meðaltal maí til september) og ársúrkoma (summafrá október fyrra árs til september) á Kirkjubœjarklaustri (a)
og í Reykjavík (b) frá 1931 til 1995 (heildregnir ferlar). Slitnir ferlar sýna vegið 5 ára meðaltal reiknað með væginu
(119,219,319,219,119)
JOKULL, No. 45, 1998
31