Jökull - 01.12.1986, Blaðsíða 74

CONCLUSION
Finally, we may sum up some of the variations in
the climate of Iceland during the years 1701 to 1784.
The winter-spring thermal index for the whole of Ice-
land shows that its mildest phase occurred at the start
of the period, from 1701 to 1710. A cooling trend pre-
dominates from c. 1710 to c. 1750. The coldest
decades were the 1740s and 1750s. As far as the whole
of Iceland is concerned the 1740s appear to have been
slightly colder than the 1750s, but the thermal index
is based on winters and springs alone. During the
1750s there were several very cold summers. It is
possible, therefore, that if the index had included all
seasons of the year, this decade would have proved to
be the coldest of the period. It is certainly during the
1750s rather than the 1740s that the climate appears
to have had most impact on society (Ogilvie, 1981).
During the 1760s there was an amelioration in the
weather, but after 1771 a further cooling occurred.
With the exception of 1781, which had a mild winter
and fruitful summer in most places, the first few years
of the 1780s were extremely cold with severe winters,
cool summers and much sea ice.
That there is a broad agreement between tempera-
ture and sea ice can be seen by comparing the thermal
index with the sea-ice index. The positive relationship
is striking in certain decades, the 1740s for example.
However, there are decades where ice and tempera-
ture appear to conflict. In the 1730s, for example, the
climate was fairly cold, but there was little ice, while
from 1701 to 1710 there was much ice, but the tem-
perature was relatively mild.
The climate of Iceland is noted for its variability on
all time scales, and the period considered here, 1701
to 1784, was no exception to this general rule. Con-
siderable regional variability was also observed. The
over-riding impression of the climate in the eighteenth
century is, however, one of great severity, character-
istic of the Little Ice Age. From a climatological
and environmental point of view, the most interesting
year of the century was undoubtedly 1783 to 1784.
From the point of view of the people who experienced
it, it was certainly the most devástating.
ACKNOWLEDGEMENTS
I acknowledge with thanks the help and advice I
have received over several years from Dr. Páll Berg-
þórsson (Veðurstofa íslands), Professor Þórhallur
Vilmundarson (Örnefnastofnun), Sjöfn Kristjánsdóttir
(Landsbókasafn Islands), Aðalgeir Kristjánsson
(Þjóðskjalasafn íslands), Professor Jónas Kristjánsson
(Stofnun Árna Magnussonar) and, especially, the late
Professor Sigurður Þórarinsson. For comments on the
manuscript I am grateful to Dr. Mick Kelly (Climatic
Research Unit) and Dr. Gísli Gunnarsson (Háskóli Is-
lands). The manuscript was typed by Ms. Nicky
Yallop. Collection of some of the data used here was
supported by NA TO research grant no. 0233/83.
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1709-1786
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72