INFLUENCE OF CLIMATIC VARIATIONS ON THE TERRITORY OF
PERUGIA AND LAKE TRASIMENO (UMBRIA, CENTRAL ITALY)
by Diana Dragoni
ABSTRACT
For some decades now, climatic variations (particularly global warming) have become one of the
most important problems facing not only scientists and researchers: they also represent a topic
widely debated in international politics and by the mass media, with a considerable influence on
public opinion, environment-friendly organisations and large industrial corporations. Concern is
aroused because global warming involves a series of environmental changes such as variations in
the quantity and regime of precipitation, glacier melting, rises in sea level, etc., with potentially
devastating effects on the biosphere, human society and its productive systems. The debate is
exacerbated because the causes of these variations on a time-scale of hundreds and thousands of
years are not clear, and there is neither scientific nor political agreement on what the most efficient
practical actions should be, both to contrast global warming and to reduce its negative effects. The
debate often tends to overlook the fact that recent, natural, climatic variations have already taken
place and have caused a series of negative consequences over vast areas of the planet. From this
point of view, the present work aims at contributing to our knowledge of the effects which some
climatic oscillations have had on the urban and rural territory of Perugia (Umbria, Italy)
In the first part of the research, as well as framing the local problem within the general area of
“global climatic variations”, the author ascertained whether and how already known climatic
variations have influenced the anthropic landscape between the city of Perugia and its surrounding
territory to the west, towards Lake Trasimeno. In particular, both towns and the road network
between the city and the lake have changed their positions in the course of centuries - for several
reasons: one important factor has been safety, but the ever-present factor is climate, which not only
gave rise to the greater or lesser creation of marshy land in the plain area, but also indirectly
influenced demographic growth and the need to increase farmland.
The second part of this work examines the effects of two particular climatic variations which took
place between 1764-1767 and 1816-1818. Literary and archive sources were consulted, for
information on the actions carried out by the authorities of the times to limit damage and to aid the
needy. The extent to which famines and the resulting outbreaks of plague were generated by
climatic or social conditions was also examined. This research shows that, during both the above
crises, the primary cause was a period of exceptionally cold and rainy weather (caused in 1815 by
the violent eruption of the volcano Tambora in Indonesia, almost 12,000 km away, which released
immense quantities of ash and other products into the atmosphere).
In spite of their efforts, the authorities were not able to respond adequately to these emergencies, for
both structural and technological reasons. The consultation of the available documents of the time,
gave information on death rates, on population trends and on the so-called “esposti” (literally
“exposed”; children voluntarily abandoned by their parents). Such information, together with
reports of health measures taken and assistance given, supply a relatively clear and emotionally
very moving idea of the impact which these crises had on the local community. The picture which
emerges is one of a society in which subsistence was primarily linked to local agriculture, its
population incapable of storing large quantities of foodstuffs, with a large proportion of the
inhabitants permanently on the brink of starvation and thus very prone to all kinds of albeit shortlived environmental stresses (climatic, social, epidemiological). The effects of these short-term
climatic variations, although they certainly did not influence what may be termed the great history,
were far from slight in terms of deaths, poverty and suffering, and should be viewed as a warning to
us of the importance of present-day climatic changes. Lastly, it should be noted that, from the
geographic viewpoint, the adaptations by the health authorities to the above two critical periods the changes, for instance, in the location and manner in which burials were undertaken and changes
in hygienic customs - are still evident and visible in the local landscape.