Jökull - 01.12.1986, Page 59

The climate of Iceland, 1701 — 1784
A.E.J. OGILVIE
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ
United Kingdom
abstract
In this paper, variations in temperature in Iceland
during the years 1701 to 1784 are discussed. For the
period 1601 to 1780, a decadal winter-spring thermal
index for the whole of Iceland, and also for the north,
south and west has been constructed. A sea-ice index
for these years is also presented. Discussion is centred
on the eighteenth century; however, because of current
interest in the Skaftáreldar (Laki) eruption of 1783,
the weather during the years 1781 to 1784 is also con-
sidered in detail. The data used are taken from de-
scriptions of the weather in contemporary historical
documents, primarily annals and official letters. As
continuous meteorological observations were not
begun in Iceland until 1846, the information gathered
ls °f great value, despite its qualitative nature. When
datafrom the whole of Iceland are taken into account,
the mildest decade of the period can be seen to be 1701
to 1710. The coldest decades are the 1740s and 1750s.
Apartfrom this, the most noticeable features of the cli-
mate of Iceland during this time are its variability,
both spatially and temporally (as during the present
day), and its severity. With the exception of 1781, the
years immediately before and after Skaftáreldar were
also very cold.
introduction
Continuous, systematic weather observations exist
in Iceland from 1846 onwards (Sigfúsdóttir, 1969).
Before this time, the climate of the historical past may
be reconstructed by using documentary evidence:
written accounts of what the weather was like at a
Particular place and time. A reconstruction of the cli-
mate of Iceland based on such evidence, and covering
the period from medieval times to 1780, has recently
been completed (Ogilvie, 1981, 1984). In addition to
all previously used sources, this reconstruction also
included material that had not been used by the pion-
eers of Icelandic historical climatology, Thoroddsen
(1916/17), Koch (1945) and Bergþórsson (1969). All
sources were carefully analysed for historical veracity,
and unreliable material that had crept into earlier
works was eliminated.
Much of the new material presented in Ogilvie
(1981) covers the eighteenth century; and it is this
period, specifically 1701 to 1784, which is considered
here. Because of the extremely cold weather which
prevailed in Iceland (and in the rest of Europe) at this
time, it is a particularly interesting period from a cli-
matological viewpoint. It should, however, be noted
that, although the eighteenth century as a whole may
be considered typical of the so-called Little Ice Age,
mild seasons and years did occur.
In the first part of this paper, decadal temperature
and sea-ice variations from 1701 to 1780 are dis-
cussed. (Analysis of data for the period 1781 to 1800
is currently in progress.) In the second part, particular
attention is paid to the years 1781 to 1784. In 1783, a
major volcanic eruption occurred in Vestur-Skafta-
fellsýsla in the southeast of Iceland — Skaftáreldar. In
the non-Icelandic literature, this eruption has gener-
ally been referred to as the “Laki” eruption. This is
inappropriate, however, as, although the eruption
occurred in the vicinity of Mount Laki, there were no
fissures on Laki itself. The lava flows and, especially,
the poisonous substances in the volcanic dust ad-
versely affected vegetation, and thereby caused the
deaths of numerous domestic animals. In the ensuing
famine, which came to be known as “Móðuharðind-
in” or “The Famine of the Mist” from the volcanic
dust haze, more than 9,000 people died (Finnsson,
1970). Because of current interest in the 200th anni-
versary of Skaftáreldar (see Gunnlaugsson et al.,
1984), it was decided to include a detailed discussion
of the weather during the eruption year, plus the years
immediately before and after it. A summary of con-
ditions during these years is given in Table 3.
SOURCES
The data sources used for this study are contempor-
ary historical documents. For the most part, these can
only supply qualitative information, and therein lies
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