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When the Lagoon was frozen over in Venice from A.D. 604 to 2012: evidence from written documentary sources, visual arts and instrumental readings


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In this paper we will combine various proxies and instrumental readings, i.e.: written documentary sources since the origin of Venice; evidence from visual arts referring to 1709, 1789 and 1791 as well as some pictures taken in 1929 and 2012; finally, instrumental observations since 1716. Of course, all documentary evidence provides insight into past climate conditions, but if separately considered, it can hardly be used to quantify climate change over time. However, taken together, proxy-data (ice cores, tree-rings, pollen, etc... ) and historical documents tell us more than either could do alone. The result of this multidisciplinary effort will be a comprehensive, critically revised list of the harsh winters, with the indication of the winters that are often mentioned, but not justified.
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Revue géographique des pays méditerranéens / Journal
of Mediterranean geography
When the Lagoon was frozen over in Venice from
A.D. 604 to 2012: evidence from written
documentary sources, visual arts and instrumental
Englacement de la lagune de Venise entre 604 et 2012 : sources historiques,
artistiques et instrumentales
Dario Camuffo, Chiara Bertolin, Alberto Craievich, Rossella Granziero and
Silvia Enzi
Electronic version
ISSN: 1760-8538
Presses Universitaires de Provence
Electronic reference
Dario Camuffo, Chiara Bertolin, Alberto Craievich, Rossella Granziero and Silvia Enzi, « When the
Lagoon was frozen over in Venice from A.D. 604 to 2012: evidence from written documentary sources,
visual arts and instrumental readings », Méditerranée [Online], Varia, Online since 07 February 2017,
connection on 09 February 2017. URL :
This text was automatically generated on 9 February 2017.
Tous droits réservés
When the Lagoon was frozen over in
Venice from A.D. 604 to 2012:
evidence from written documentary
sources, visual arts and
instrumental readings
Englacement de la lagune de Venise entre 604 et 2012 : sources historiques,
artistiques et instrumentales
Dario Camuffo, Chiara Bertolin, Alberto Craievich, Rossella Granziero and
Silvia Enzi
This research has been made under the EU funded project Climate for Culture (Grant 226973).
The authors are grateful to Arch. Patrizia Schenal, Dr Laura Megna, Dr Mirca Sghedoni, Dr Leila
Gentile, Dr Lorenza Mettifogo and Dr Luca Fraulini for their contribution in recovering and
commenting documentary sources and to Dr Ruthy Gertwagen, Haifa University, and Dr Georges
Pichard, Aix-Marseille University, for useful discussions and suggestions. Thanks are due to the
three referees for the careful revision and useful comments.
1. Introduction
1 The remote origin of Venice in the marshes of the Northern Adriatic Sea is related to local
peoples that escaped from Germanic and Hun invasions in the 5th century A.D. and
formed a community organized for mutual defence. In 751 the Duchy of Venice became
independent from the exarchate of Ravenna1, and in 803 was recognized as Byzantine
territory. At the end of the 9th century was a flourishing Republic, nicknamedLa
Serenissima” (the Most Serene Republic). After the Fourth Crusade (1202-04) with the
capture and sack of Constantinople, Venice became an imperial maritime power. In 1797
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the invasion of the Napoleon Army determined the fall of the Venice Republic. In 1806
Venice become part of the Napoleon's Italian kingdom with Milan capital2, followed by
the Austrian dominance of the Lombardy-Venetian regions (1814-1866)3. After popular
unrests and battles, Venice joined the unified Reign of Italy in 18664. For its long history
and maritime trades, Venice had special links with the Byzantine Empire and the Orient,
but also strong relationships with other European countries, that influenced in various
ways its activity and culture.
2 In this paper we will combine various proxies and instrumental readings, i.e.: written
documentary sources since the origin of Venice; evidence from visual arts referring to
1709, 1789 and 1791 as well as some pictures taken in 1929 and 2012; finally, instrumental
observations since 1716. Of course, all documentary evidence provides insight into past
climate conditions, but if separately considered, it can hardly be used to quantify climate
change over time. However, taken together, proxy-data (ice cores, tree-rings, pollen, etc…
) and historical documents tell us more than either could do alone. The result of this
multidisciplinary effort will be a comprehensive, critically revised list of the harsh
winters, with the indication of the winters that are often mentioned, but not justified.
1.1 Documentary written sources
3 A reliable written source is a document that should be geographically and chronologically
close to the facts, possibly written by an eyewitness. Documentary sources are extremely
useful to reconstruct the past climate, especially for the period prior to the instrumental
records. They provide data and details especially significant when cross-compared with
natural proxies. They may include general descriptions useful to interpret the weather
situation and the impact on environmental and society, what is not always possible with
the instrumental readings alone.
4 However, some degree uncertainty is inevitable due to the cultural evolution and the
change of interest to natural events5. For instance, in the Middle Ages the natural events
were considered a direct sign of the Heaven, especially those occurring in the sky (that
included the atmosphere), either to punish mankind or as an advertisement to change life
style. In the Renaissance the natural events lost part of their religious significance and
became lay and curious events to be collected and listed to amaze, improve erudition and
knowledge. After the Galileo’s cultural revolution and especially in the times of
Enlightens, they became object of study, an input for the scientific research. In addition,
the cultural level of the eyewitness (and the author who collected and reported data) was
crucial in determining the quality of the information. The survival of a memory is linked
to the perception of its importance, both for public and private reasons. This perception
changes depending on the cultural atmosphere the authors is part of. Therefore, literary
sources evolve differently in quantity, quality and typology over time. It is essential to
keep in mind this evolution in order to interpret data and assess the correct uncertainty
band, as we will discuss later.
5 Venetian documents provide a unique opportunity for reconstructing a long series of
extreme events that have characterized the past climate over one millennium.6 Our
research has been conducted in Venice and outside Venice as well. In Venice, historical
documents are kept in the Marciana Library, Correr Museum, Querini Stampalia
Foundation, State Archive and other public and private collections. In particular, the
State Archive was founded in 18157 to reorganize collections and reconstruct the history
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of Venice: it preserves documents for about 80 km of shelves. The records are written in
Latin, Venetian, early and modern Italian and include official, public and private
documents of the central and local institutions, local and foreign political and
administrative records, diplomatic and informative letters from foreign embassies, ship
logs, professional and artisan guild records, notary archives, brotherhoods, associations
and confraternal archives. The documents provide descriptions of weather events and
their impact on the society, the agriculture and the landscape. Interpreting these data
allows determining the level of severity of the events that happened before the
instrumental observations of air temperature, pressure and precipitation.
6 The Digital Humanities Laboratory (DHLAB), founded in 2012 by Frédéric Kaplan, is
developing new computational approaches for document digitalisation, under the ‘Venice
Time Machine’ project, jointly supported by the Ecole Polytécnique Féderale de Lausanne
and the University of Ca’ Foscari, Venice8. The aim is the digitalization of millions of
documents over the last one thousand years; the project will make much easier the
research in digital form. Another useful digital source is HISTRONE-CEREGE9 with
hydrological and climatic data with special reference to the basin of the Rône River.
7 In the Middle Ages the information was rare, especially in the dark period before 1100.
The population was scarce, lived in very bad conditions and was unable to read and write,
except a few persons, mostly clergy. In times in which it was difficult to survive, the
interest to document weather and climate was very low. In addition, the few documents
that were produced were not kept in the best conditions, and not all of them survived
fires, floods, wars, dismantlement and other challenges. Possible information gaps are
due to dramatic fires occurred in Venice, especially in 976, 1105, 1149. A question is
whether the period from 853 to 1119 is a gap for scarcity of documents, or passed
unobserved being characterized by normal or mild winters as a result of the Warm
Medieval Optimum? Our research confirms the former hypothesis, while the second
remains obscure.
8 A general problem is that the recovered series of data should be complete, because a
missed winter may be misinterpreted for a “normal” winter that was neglected because it
had no particular features. The problem is that the number of events per each class in
unknown. As an exercise to test completeness of a series and at the same time have a
general view how the cultural approach changed over time is given in Fig.1, that
compares the completeness of our data bank as it was some ten years ago, after some
thirty years of traditional documentary research in archives and libraries, before the
digitalisation of many historical documents was available with rapid improvement of the
stuff. We should explain that in our Data Bank, in addition to weather events and natural
challenges, we reported the solar and lunar eclipses that we have found in the documents
because they were precious to exactly date the weather events happened in the same
period. The underlying idea is that we exactly know the real number of astronomical
events (AERN), e.g. comets, eclipses, which are calculated with astronomical formulae10,
and we can compare this number with the same type of events recovered in our data bank
(AEDB). At this point we can compute the completeness in terms of percentage11, i.e. [(AERN
)/(AEDB)] ×100. The total number of primary (i.e. direct eyewitness) and secondary (i.e.
reported by another writer) sources is also reported in the same figure.
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Fig. 1
Upper row: Percentage of the number of solar and lunar eclipses recovered with other natural events
in our Data Bank (year 2000) in comparison with the total number of eclipses occurred in the same
period (i.e. century by century), and known after astronomical calculations. Lower row: Number of
primary and secondary sources that have been consulted. For symbols A, B, C, see comments in the
9 The number of available and consulted sources and the percentage of the eclipses (as an
index of completeness) over time are reported in the plot. In the first millennium of our
era (label A) the number of sources is very low and is associated with a very low
percentage of eclipses. This means that the information is largely incomplete. In the
upper row, in the period B from 1000 to 1400 the percentage of eclipses is very high
(around 70%) especially considering that the sky is naturally overcast with thick cloud
cover at least for 30% of the time. In this period the “sky” was composed of a unique
complex system of spheres including stars, planets and the atmosphere. In the upper row
we see an abrupt transition to C, that is due to cultural factors: after the discoveries of
Nicolaus Copernicus, Tycho Brahe, Johannes Kepler and Galileo Galilei, the eclipses
became natural celestial phenomena studied by astronomy and were distinguished from
the weather events in the atmosphere. In our Data Bank (Fig.1 lower row) the passage
from B to C corresponds to the reduced need of documentary data, substituted by
instrumental readings, except for a common period necessary for the calibration and
validation of the series. This examples elucidates how dark and incomplete is the first
Millennium, and suggests prudence in drawing climatic conclusions only relying on
documentary sources.
10 The next severe challenge to the documents in Venice happened in 1797, when the
Napoleon Army determined the fall of the Venice Republic and dispersed most
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documents, although some of them were given off in 1869 after the Austria-Italy
11 In some cases the content of certain documents survived because they had been copied
into chronicles or compilations. For instance, the German book dealer Amadeus Gottlieb
Schweyer living in Venice and locally named Amedeo Svajer, collected thousands of
manuscripts and books of social and political interest for Venice, including plagues,
extreme weather and natural disasters. This was an unparalleled collection about the
history of Venice. When Svajer died in 1791, his brothers decided to sell the collection,
which was dismembered 13. The Inquisition of the Venice Republic controlled the
collection, found 900 confidential documents and confiscated the most critical ones (some
252 diplomatic letters and reports to and from foreign embassies) in a special archive of
the political Court. Most books were bought by the bookseller Scapin in Padua; 721
manuscripts were bought by the Civic Library Joppi, Udine; 340 codices were purchased
by the Marciana Library, others by the Museum Correr; the 252 diplomatic documents
passed to the State Archive; the books and documents given off by Austria in 186914 were
dismembered in various archives. The rest of the Svajer’s collection was scattered over
Europe. However, when Svajer was alive, the local chronicler Father Giovan Battista
Gallicciolli consulted per years the collection, as well as other public and private archives
and libraries in Venice to compile a holistic chronicle of Venice published with the title “
Delle memorie venete antiche profane ed ecclesiastiche (early secular and ecclesiastic
Venetian memoirs) (Gallicciolli, 1795)15. Except for the title, this text is almost identical to
another anonymous manuscript “Cronaca Veneziana o meglio Zibaldone con molti ricordi
meteorologici” (Venetian Chronicle or Hotchpotch with several weather memories), kept in
the library of Correr Museum. We believe that the anonymous manuscript is the draft of
the publication by Gallicciolli printed in 1795. In the following, will quote only Gallicciolli
1795, disregarding the parallel handwritten Hotchpotch. Gallicciolli accurately copied
representative fragments of the original documents and shortly reported the source in
contracted form, or the archival number of the collection, either the Svajer’s or other
ones. Although weakly quoted, Gallicciolli preserved many useful fragments of unusual or
extreme weather events of which the original source has been dispersed or lost. In this
paper, the documents of the Svajer’s collection that have been found in other archives or
libraries have been quoted according their modern classification. Some other of these
documents might have survived, but so far it has not been possible to find them. The lost
documents have been cited with their original quotation, e.g. Svajer No 421 and No 865.
Gallicciolli was very accurate for his time, although in some cases he misled dating and
caused duplications of events for the reasons we will discuss later. Gallicciolli was a
source directly or indirectly used by a number of climatologists specifically interested to
Venice,16 or Europe in general 17, generating the problems we will discuss later. Gallicciolli
followed the example of other famous catalogues, as follows.
12 Julius Obsequens, a Roman writer of the 4th century A.D., wrote the Liber de Prodigiis (Book
of Prodigies) including the wonders and portents that occurred in Rome from 249 B.C. to
12 B.C.18 The book was edited and printed by Aldo Manuzio in Venice in 1508.
13 On request of his friend George Syncellus, the Byzantine monk Theophanes the Confessor
continued the Syncellus’s ChronicleChronographia a chronology of world events,
covering the period from the rule of Diocletian in A.D. 284 to the downfall of Michael I
Rhangabes in 813. The Chronicle was written in Greek, and dated in years since the
Creation of the World.
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14 In 1555, Markus Fritsche19 (who signed Marcus Frytschius Laubanus) of Greek origin, i.e.
"Hexapolensis"20 as he defined himself, in the middle of the 16th century, published in
Nurnberg, Germany, a book written in Latin, i.e. theCatalogus Prodigiorum (Book of
Prodigies, where "prodigies" stays for: extraordinary, upsetting things) 21. The book is an
extensive catalogue of the most impressive meteorological and celestial events, ordered
year by year, since the Creation of the World. He used double dating. In the B.C. era he
used as a reference the Creation and the foundation of Rome; in the A.D. era he used the
Creation and the years of Christ. He quoted in abbreviated form his sources. Some of
them are understandable, other remain obscure. Fritsche was used as a (secondary)
source by leading historians of climate in the next centuries.
15 In 1605, Sethus Calvisius, a German musician as well as chronologist and astronomer,
published the book “Opus Chronologicum” later updated to 1629 by J. Zhym and to 1685 by
Wolfgang Philipp Kilian22. Clavisius reported a detailed list of the main political and social
events, including natural hazards and extreme climatic events since the antiquity, dating
the facts in year after the Creation and relating them to the Common Era as well.
Calvisius included several facts concerning Venice and was considered a milestone
16 A key reference was Father Secondo Lancillotti who published in Venice in 1627 a
comparison between the situation at his time and how it was in the past under various
aspects: e.g. ethical, social and catastrophic including plagues and natural hazards. The
short name of the book (in Italian) is “Hoggidì” (i.e. Today). The events are listed with the
year as heading on the side, and the source is mentioned but much shortened: some may
be guessed and found after various attempts, other remain obscure. The book is written
in Italian and was a main reference for Giuseppe Toaldo, but not for other scientists
unfamiliar with Italian. However, Toaldo wrote in Italian, Latin and French and was
translated in German and English. This allowed the transmission of most events quoted
by Lancillotti, but the official source became Toaldo.
17 Another catalogue of meteorological events including harsh winters was made by
Giuseppe Toaldo in 1770, and particularly in the 2nd edition in 1781 and the last update in
1797.23 Toaldo was a famous and excellent astronomer and meteorologist living in Padua,
located 40 km West of Venice, and his papers had a wide diffusion over Europe. From 1766
he performed records of instrumental observations and tried to find how far astronomic
factors influenced weather. For this purpose he collected a huge amount of data and
events from any available source, either direct witnessed or second-hand compilations.
He acknowledges that, in general, his main sources were “Fryschio” (i.e. Marcus Fritsche),
“P. Lancillotto” (i.e. “P.” for “Father” Secondo Lancillotti) and Collezione Acad. T. IV”.
Probably, he intended the Collection l’Académique published at intervals of a few years at
Dijon and Paris; this journal included summaries and articles of foreign works translated
in French. The fourth Tome (i.e. T. IV) was focused on natural history, botanic, physical
and chemical advances, medicine and anatomy. Toaldo consulted various issues searching
for news of extreme meteorological events and other natural hazards. His aim was to
build a database of meteorological events to be related to astronomical cycles. In his
works, Toaldo only seldom reported the source in a very abbreviated form; he did not
seek for the original documents and accepted the items available in compilations without
verifying the content or checking dates. This generated some errors and duplications that
were transmitted to later historians of climate, as discussed elsewhere.24 However, for the
astronomical or meteorological observations he made, and for the contemporary period
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of which he was a witness, Toaldo is absolutely reliable. Toaldo could not take advantage
of the Gallicciolli’s book because it was published in 1795, two years before Toaldo died.
18 Several other studies were made on harsh winters, although not focused on Venice. In the
following we will quote some of them to help interpreting the transmission of data and
possible duplications of events.
19 In 1788, Anton Pilgram, an early climate historian and statistician from the University of
Vienna made a very careful collection and statistical analysis of weather events from the
existing literature and published it (in German) with a list of the winters in the common
Era (more exactly since A.D. 401), with a comment on their severity25. He quoted (but not
controlled) all sources, either primary or secondary ones, including compilations (e.g.
Lancellotti, Toaldo). The work has a modern approach and inspired later works: certainly
Tilloch, but very likely Arago, Hennig and Easton26 too; the latters preferred to mention
the original source, omitting to quote Pilgram.
20 In 1809, Christoph Heinrich Pfaff from Kiel published (in German) a description of the
harsh winters since A.D. 140027 with a few mentions to some previous exceptional
winters, e.g. 1269, 1323. He relied on four papers, published from 1753 to 1800, mostly
dealing with winters occurred on the previous century. This work was used by Tilloch and
others therein.
21 In 1820, Alexander Tilloch, editor of The Philosophical Magazine and Journal, published the
History of the Weather where he reported a list (in English) of all major weather events
occurred in the Christian era, including the harshest winters. As Toaldo, he did not
mention and control his sources, except in the introduction where he declared that relied
on Toaldo, Pilgram and Pfaff. It is quite surprising that Tilloch accepted without a critical
revision the above contributions because in the foreword he made excellent and prudent
introductory remarks, i.e.: “'Prior to the instrumental period, we must glean our
information from the loose and scanty notices which are scattered through the old
chronicles relative to the state of the harvest, the quality of the vintage, or the endurance
of frost and snow in the winter. Great allowance, however, should be made for the spirit
of exaggeration and the love of the marvellous; which infect all those rude historical
monuments.”28 By the way, Tilloch anticipated by one and half century the idea of
Emmanuel Le Roy Ladurie to reconstruct the spring-summer temperature in Borgogne
from grape harvest dates. 29 The list of weather events by Tilloch was a very useful source
for later chroniclers and historians of climate, and caused several duplications too. A
number of events concerning Italy were not confirmed by our local contemporary
sources. In general we will disregard this, and other late compilations, except for
discussing the reliability of some winters, especially in the 17th century.
22 In 1821, Gabriel Peignot wrote (in French) a paper with a detailed list of the harshest
winters from 396 BC to 1821, with a short description of the most impressive events. The
sources were quoted, but not always.
23 In 1858 François Jean Dominique Arago30 with the cooperation of J.A. Barral published (in
French) a huge stuff of climatic data, including a Chapter devoted to the winters when the
great Rivers were frozen. He reported the text (translated in French) and the sources, all
of them supposed to be accurate and reliable. This work was very popular and became a
useful reference for historians of climate.
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24 In 1904 Rudolf Henning31 published (in German) a very extensive catalogue of remarkable
weather events indicating the sources but without a critical evaluation of them. This
work was a milestone reference.
25 In 1928 Cornelius Easton32 published a catalogue listing all winters in Western Europe,
quoting the sources. Each winter is introduced with keywords or a short sentence that
summarizes the various sources. The book is in French, but several quotations are in the
original language, and this is very useful for a better evaluation of the original text. No
comments are reported about the sources. This also was a milestone reference.
26 In the second half of the 20th century, the reconstruction of the past climate became a
mature science with collection and revision of historic data and sources interpreted in
terms of weather or climate analysis. Pioneers have been Hubert Lamb in UK, Emmanuel
Le Roy Ladurie in France, Christian Pfister in Switzerland, Gaston Demarée and Pierre
Alexandre in Belgium, Rudolf Brazdil in the Check Republic and many others.
1.2 Visual Arts as Documentary Sources
27 A totally different source of information that we will use in this paper is constituted of
visual arts that illustrate what we find in written documents. These visual arts are kept in
a number of institutions, i.e. Foundation of Civic Museum (MUVE, Venice, that includes
Ca’ Rezzonico and Correr Museum cited in this paper), the Querini-Stampalia Foundation,
private collections in London.33 In addition, some interesting pictures exist, documenting
the Lagoon frozen in 1929 and more recently as well.
1.3 Instrumental readings
28 Meteorological records of daily temperature observations that started in 1716 in the
Venice area, including Padua, are another vital source of information.34 We have
recovered, corrected and analyzed all the related instrumental records.35 Padua was rich
of scientific observations, because the local University, founded in 1222, was interested in
all disciplines, with leading teachers. Giovanni Poleni in 1719 had a chair in Mathematics
and Experimental Philosophy, and then Astronomy Mathematics and Navigation, and
began daily weather observations in 1716. Giuseppe Toaldo in 1764 had a chair in
Astronomy and Meteorology and in 1766, after the death of Poleni, continued the series of
meteorological observations including detailed descriptions of weather extremes. This
long instrumental series has been continued till today.36
29 We have also consulted the weather readings of the Patriarcale Observatory, Venice, that
are reported in form of Daily Logs with notes. This Observatory is located in the City
centre and was active from 1835 to 1951. After it was closed, the nearby Istituto Cavanis
continued the readings since 1959.
30 A further source of instrumental readings from 1950 is the Italian Air Force Weather
Service at the Venice airport on the border of the Lagoon. The records of the
instrumental period allow to reconstruct the weather maps and the general circulation.
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2. Dating styles in Italy and duplication of events
31 In Venice dating was complex and sometimes ambiguous due to the use of a number of
different styles that co-existed until the fall of the Serenissima in 1797. The various dating
styles are37:
More Veneto (i.e. Venice Style) calendar with the year beginning on March 1st. This is the
most official and popular style of the Republic till 1797.
"Circumcision of Christ" or "More Romano" (i.e. Rome Style) calendar beginning on January 1st ,
as the modern style. It may be indicated A.D. i.e. anno Domini, Latin for “in the year of our
Lord.” From the origin of Venice to October 4th 1582 it coincided with the Julian calendar;
after October 15th 1582 with the Gregorian calendar38. Since 1520 it was sometimes used in
private acts. Before 1797 it was used for official documents sent to foreign people not
familiar with the More Veneto. It became the official style after 1797.39
“Byzantine” calendar: from September 1st, anticipated by 4 months. This was the official
calendar of the Byzantine Empire from 988 to 1453 i.e. the fall of Constantinople and the end
of the Byzantine Empire, followed by the Ottoman Empire (1453-1922). This style used the
Annus Mundi” or “Ab Origine Mundi (AM, Latin for “Year after the Creation”) that was
established 5,509 years before the Incarnation of Jesus Christ.
Constantine Indiction or Caesar Indiction”, or "Beda Indiction" or shortened "lndiction", after
the emperor Constantine, based on the taxation date, starting from September 24th. Each
Indiction was composed of a series of 15 years that were numbered from 1 to 15, returning to
1 at the next Indiction. It was used in the early period of the Republic when the link with the
Byzantine Empire (330-1453) was strong. Critical dates were: 1204 when Venetians and the
crusaders of the IV crusade captured and sacked Constantinople; 1453 with the fall of
“Constantinople Indiction”, or “Greek Indiction” or shortened "lndiction", based on taxation date,
from September 1st. This style was in use in the early period of the Republic, during the
Byzantine Empire.
Roman Indiction” orPontifical Indiction or shortened "Indiction", from December 25th. This
was used in the last period of the Republic, when the Byzantine Empire was ended,
substituted by the Ottoman Empire.
"Magistrati" or "Civil Collegiale" (local Authorities) calendar, starting from St. Michael feast,
i.e. September 29th).
"Hagiographic calendar”, a monastic use where each day of the calendar year is linked to an
individual Saint. This style was particularly popular in the Byzantine area, with calendar-
icons composed of 365 Saints. This calendar does not establish the year but the day and
“From the Rise to Power” of the Doge. The Doge was elected for life by the Venice aristocracy
and was the chief magistrate of the Republic, with great temporal power. This dating style
indicated the year of power of each Doge, and was an ambiguous substitute of the year
because the start was random, and the same year Doge style was spread over two years More
Romano. Fortunately, the chronology of all Doges is well documented.
“Closest Milestone”, i.e. making reference to some famous natural or social events used as a
milestone, e.g. passage of a comet, eclipses, famine, earthquake, battle, death of a king. This
dating style was particularly popular in the antiquity and the Middle Age. The use was to
quote the closest among the possible temporal references that had a special social or
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psychological impact. A problem is that the reference event may have occurred before or
even after the particular event the author was dealing with.
32 Other additional calendars were used in documents referring to Venice but written in
other Italian cities. The use changed with the cities and over time, following political
events. The most important dating styles were:
“Easter”: from the Easter Day.
“Incarnation”, Florence style, used in Florence, Piacenza and other cities: from the 25t h March
postponed by 84 days compared to the Julian and Gregorian calendars A.D., i.e. More Romano
(beginning on January 1st).
“Incarnation” Pisa style, used in Pisa: ended March 24th, anticipated by 281 days.
Nativity: from December 25th, occurring 6 days earlier.
“From the Rise to Power” of the local Governor (e.g. Pope, Emperor, Prince, Captains, Regents)
with random start.
From the Foundation of Rome”, i.e. April 21st, 753 BC.
33 The main problem is that the dates are almost always reported without specifying the
dating style, Indiction type etc. For the local writer the choice was obvious and no
specification was needed. However, after a long time has passed, this created ambiguity
or misunderstanding. For instance, an event happened on January 1500 (in terms of the
Julian calendar) was dated: 1499 if the writer used the Pisa Incarnation style; 1500 if used
More Romano or Nativity or AD; 1501 if used More Veneto, Easter or Florentine Incarnation. This
example shows that a date may have an uncertainty of ±2 years. The situation is
particularly critical for the winter severity, as the extreme cold is usually reached in
December, January or February that may belong to the same or the next year, depending
on the particular calendar used. This complex and misleading system explains why some
dating remains uncertain, or created duplications, especially for the mediaeval period. All
the dates reported in this paper will follow the modern style, except when quotations are
used. The analysed sources show that the most frequent period for the Lagoon to freeze
over is from January to February and, only very rarely, in December. Therefore, when no
specification of the month is found, the most probable assumption is that the winter date
is related to January or February.
34 Another consequence of the complex dating styles, or the use of secondary sources (i.e.
not direct witness) is the single (or multiple) duplication of events. In particular, most
historians of climate since the beginning of the 20th century omitted to mention how they
knew the fact, making almost impossible to verify the source. For this reason, a critical
analysis of the text is necessary, based on the optimization of three criteria: climatic,
statistical and historical, as follows
35 From the climatic point of view, it is evident that some dates are wrong. For instance,
suppose to find a great winter (GW) mentioned in a manuscript but not in others dealing
with the same time period. A great winter cannot be local and should be perceived by all
people of a wide geographic area. It is not physically realistic that a certain winter is
considered GW by a source and normal by another. Finally, the various effects described
in the text should be physically consistent.
36 From the statistical point of view the probability that an extreme event returns in the next
year is extremely low. A great winter generally occurs twice or three times per century.
Suppose the case of a century with two GWs. The probability that a GW falls in a selected
year is 0.02, but the combined probability that in the second GW falls in the next year is
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about 100 time smaller40. As human errors in the transmission of the date (especially for
secondary sources) have a much higher probability, when extreme events are found in
two consecutive years they should be considered suspect, and a careful analysis is
37 From the historical point of view, the simultaneous existence of various and undeclared
dating styles, misprints or errors in reading, interpreting or copying previous documents,
may cause misleading dates or duplications of events. The most favourable case is when
the text reports some astronomical events (e.g. eclipses or passage of comets) that can be
verified with astronomic calculations, as we did it. Internal controls are possible: if a
specific day of the week is mentioned in addition to the date, name of the day and date
should match for the specified year; if not, another year should found in which they
match. To reject an event because the source has not been well identified means to deny
that this event had occurred, and this may constitute a serious error in the climate
reconstruction. A weak source means to start a long hardworking to verify or to deny the
obscure event.
38 Briefly, two extreme winters at short distance between them are credible only in the case
they have been recorded in the same source, contemporary to the events. When they
derive combining two or more sources that mention only one of the two winters, almost
certainly one of the two is a false duplicate. Extreme events mentioned in different
sources, but differently dated, need an accurate critical analysis to establish the most
probable dating. In past climate reconstructions, it is unavoidable that some events may
remain obscured by uncertainties. In the case of doubt, this should be notified; after, the
key question is: to accept or to reject? Which of the two options may cause the greatest
possible error in the climate reconstruction?
3. Classifying and defining the winter severity from
written documents and visual arts
39 When we have instrumental records, the winter severity is evaluated from the
temperature level reached during the winter, and the time duration in which the
temperature was below certain selected thresholds. In the period before the instrumental
records, however, we must rely on proxy data41, also called proxies. Historical documents
and visual arts contemporary to the events are useful proxies, because they contain a
wealth of information about past the climate and the ice sheet. The interpretation of the
above proxies is based on the effects generated by cold. It is possible to establish a class of
severity, based on some specific objective consequences, easily recognizable in the
historical documentation. In this paper, the winter severity has been classified in four
categories, from the mild to the coldest, i.e.: mild, normal, severe, very severe and great
40 Mild” winter was considered warmer than usual, without frost events, and with early
vegetation. In a mild winter a modest use of wood for domestic heating was required. No
ice is formed on the Venice Lagoon.
41 Normalmeant average or passed unobserved, without comments about its severity or
its ramifications on the society and economy. No ice is formed on the Venice Lagoon.
42 Severe” winter (SW) was identified according to the many complaints made by a number
of separate sources. A winter is considered severe if the intense cold persisted for a short
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period with frost, but large water bodies were not completely frozen over. In Venice, ice
slabs formed inlands on the freshwater of rivers or on the borders of the Lagoon, where
shallow water lasted for a long time without exchanges with the sea. Often the Lagoon
birds who used to nest there were entrapped with their legs in the ice. Discharged from
rivers, the ice slabs that arrived into the Lagoon were hardly visible and formed icebergs
that endangered the small Venetian boats. This was one of the reasons Venice initiated
the diversion of the main rivers outside the Lagoon; the main reason, however, was to
clean the Lagoon from fluvial siltation42. Two examples of SW are reported. The first, "On
February 22nd 1814, there was cold with fresh wind. On the 23rd, ice was floating on canals.
On the 24th, fresh wind transported slabs of ice. The navigation was dangerous and was
stopped"; the temperature was -6°C.43 The second case was “On January 29th, 1855; some
slabs of broken ice were floating in the Lagoon. Several canals between Venice and the
mainland froze and prevented navigation. There were also some casualties. The edges of
the canals in Venice were covered with ice. On the morning of the 21st [with minimum air
temperature -8.8°C] many slabs of ice were floating on the Grand Canal, arriving from the
canals between Venice and mainland. On the 24th too some ice was still floating".44
43 Very severe(VS) winter was thus classified when the cold killed people, animals and
plants and caused to the complete freezing of springs, wells and large bodies of fresh
water. The Lagoon around Venice, characterized by shallow waters and smaller water
exchange, partially froze, and the deep canals crossing the City, characterized by larger
water exchange, were covered with ice slabs. Furthermore, the ice made impossible the
import of food and beverages from the hinterland and caused to the City to be besieged
by the cold. Theoretically, the only possibility to get new supplies was by the sea.
However, internal shipping was extremely dangerous, not only due to floating slabs, but
because most ships were entrapped in the ice, and it was impossible to reach and save
them. In the case of very severe winters the Venice Republic provided the poor people
with leftover wood from the public shipbuilding industry, the Arsenal, for heating and
cooking purposes, for their survival.45
44 Great winters(GW) are extreme exceptional events that generally happened once in a
century. The extreme cold lasted for weeks, killing people, animals and trees. The wine in
barrels46 and the water in all springs and wells froze, as in the VS winter. In addition,
large bodies of water were covered with thick ices slabs that could carry heavy weights.
At a certain point the thick ice sheet in the North-Eastern side of the Lagoon from Venice
to Mestre in the hinterland, along the sides of St. Michael and Murano islands (Fig.2),
supported the weight of people, animals, barrels, carts and even wagons.
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Fig. 2
Path over the frozen Lagoon frozen from Fondamenta San Giobbe in Venice to Mestre in the
hinterland, through S. Secondo Island (yellow arrow); the second path is from the Fondamenta Nuove
passing on the side of Saint Michael Island and across Murano Island (red arrow).
Arrows have been applied to a xylography by Jacopo De’ Barbari (16th century, Correr Museum) with a
realistic aerial view of Venice and its Lagoon. Correr Museum, Venice, inv. Cl XLIV n. 57)
45 A new pathway was thus created that raised the siege off the City. This situation is
illustrated by a funny xylography (Fig.3), whose legend in the bottom reads: “Activities
made on ice 1st January 1789 and a pulled cart with poultry and mail”. Furthermore the
thick ice created new vast areas for people amusements and games exhibited by this
xylography, paints and etchings, discussed later. A similar situation with analogous
effects took place in Europe. In France, eight months after the event, Father Louis Cotte
reported that the severe frost of the great winter 1788-89 killed animals (e.g. hens and
turkeys loft their legs sucked in ice; fish in shallow waters), fruit and forest trees and
other vegetables (including winter barley, corn and wheat). The frozen water did not
enable grinding wheat.47 Furthermore, the frozen fresh water hampered the transport of
supplies from the countries nearby, leaving French people without bread and in the
famine. This situation, bad climate and food shortage accelerated the onset of the French
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Fig. 3
A xylography dated 1789 showing the caravan of people, animals and food provisions coming on ice
from the mainland, in the horizon, to Venice .
Correr Museum, Venice, St. Gherro n. 2177)
4. The formation of ice slab on the Lagoon
46 The Venice Lagoon has a surface area of around 550 km2 and, although it is only one
water body, for the internal circulation it may be considered composed of three parts:
Eastern, Northern and Western, each of them with its own gate to the Adriatic Sea. When
Venetians use the term Lagoons, it means that all the three parts are considered; the
singular term, Lagoon, means either the whole Lagoon or one of the three parts,
depending on the context. The common use by modern documents is the singular term.
The documents considered in this paper define "marshes" the shoal areas, either with
shallow water or no water at all, depending on the tidal phase. The Lagoon water is
generally shallow, but some deep canals cross it to allow the transit of boats and to reach
the Sea. The City of Venice is a cluster of small islands carved out of a swamp: they are
joined together by bridges and crossed by canals. Shallow waters and deep waters
respond in a different way to local water circulation and frost, as we will discuss later. In
this paper we will limit our analysis to the harshest winters in Venice, that is, the VS and
GW when not only the marshes, but the wide and deep canals too were frozen.
47 When historical documents are cross compared to verify their agreement and assess the
winter severity, one might expect to find that the Venice Lagoon is in the same conditions
as the lakes and rivers of Northern Italy, i.e. either covered or uncovered by ice. However,
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it is necessary to keep in mind that the physical situation of a Lagoon is different from
lakes and rivers for three reasons, as follows.
48 (i) Water composition. The most obvious difference is that the Lagoon is composed of salty
marine water, while lakes and rivers of fresh water. The marine water has a salt content
of about 3.5%, which lowers the freezing point to about -2°C. Before the works made by
Venetians to divert the rivers outside of the Lagoon48, i.e. 14th to 18th century, the salinity
in the Lagoon was a bit less and so the freezing point. The contribution of rainfall to
salinity is negligible because the winter precipitation in this area is 50-60 mm/month, but
the weather situation responsible for icing is characterized by extremely cold and dry air
blowing from North and no precipitation for the whole period. Ice that forms from
freezing seawater is composed of a regular crystalline structure where salt cannot be
included. This means that marine water freezes when the temperature drops below -2°C
but will melt when it exceeds 0°C. Freezing and melting occur at different temperatures,
differently for the fresh water of lakes and rivers that freezes and melts at 0°C.
49 (ii) Heat balance and tides. In winter, any water body looses heat towards the atmosphere
(by evaporation, intense infrared loss when the sky is clear49, heat conduction and wind
convection) and uptakes some heat from the bottom and the solar income50. The above
balance determines the water temperature: in winter the shallow water of the Lagoon is
cold while the Adriatic Sea is warmer, e.g. 8-10°C51. However, at each tide the Lagoon has
an exchange of water -and heat- with the Adriatic Sea, and the tidal cycle is governed by
the lunar phases. At the first and last quarter Moons, the tidal range and the water
exchanges with the sea are minimum; at new or full Moons are maximum.52. This
particular synergism of lunar and solar forces brings inside the Lagoon smaller or larger
amounts of mild seawater that opposes the formation of ice, or tends to melt the ice sheet
from below. In order to be frozen over, the Lagoon should be exposed to extremely cold
wind for a certain period, e.g. one or two weeks. Lakes and rivers too may freeze under
the same conditions. However, differently from the Lagoon, they respond to the
cumulative effect53 of continuous cooling over a long time (e.g. months) although the cold
is less intense. For lakes and rivers the water temperature depends on the total heat lost,
either short-term intense cooling or long-term moderate cooling. This justifies why at
times the Lagoon, lakes and rivers in the same climatic area are simultaneously frozen
over, while other times only lakes and rivers are covered with ice.
50 (iii) Capability of accumulating ice slabs. Rivers may transport slabs of ice formed near the
borders and the slabs of ice may be stopped at bridges or meanders, where they will join
together. When a number of ice slabs accumulate on the same restricted area, they may
join together forming a very thick slab acting as a bridge, while the rest of the river
remains unfrozen. The Lagoon too may have ice floe areas, especially near the borders or
transported by rivers or inland canals, but this is of little relevance. When floating ice
slabs are enough, they will collide with each other and might join together expanding the
frozen area. The further development of ice is conditioned by the balance between tidal
exchange and further atmospheric cooling for cold air, strong wind and clear sky for
infrared cooling. In other words, when the Lagoon is frozen over, it is very likely to find
lakes and rivers frozen too; the vice-versa is not necessarily true.
51 The Lagoon has a short relaxation period determined by exchanges with the open sea,
and the critical factor for freezing is that the intense cooling should exceed the heat
supplied from the sea at each tidal cycle. Thick ice slabs form on the Lagoon when the air
temperature drops below -10° to -18°C for one or two weeks or even for longer. The most
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effective mechanism for the Lagoon to freeze is snow followed by polar air blowing from
North, locally resulting in strong Bora wind from North-East. When snow covers the soil,
the air in contact with it never exceeds 0°C; the Bora increases evaporation from the
water surface and further cooling.
52 The Lagoon has shallow waters and some canals as well, and we have seen that the water
temperature mostly depends on the tidal exchanges with the sea. Ice is thicker on borders
and marshes, but thinner or even missing on the canals. To the expert eye of local people,
in the absence of frost, the canals are recognizable from the different refraction of the
waves, but this is not possible when there is an ice cover. However, the main canals are
marked with poles implanted on the canal borders. When both the Lagoon and the canals
are covered with ice, the ice on the canals is thinner and the poles indicate the most risky
areas where some mild water flows below for tidal exchanges.
53 It is hazardous to walk on ice when its thickness is less than 10 cm. The ice sheet is safe
for the weight of individual persons when the thickness exceeds 18-20 cm throughout the
entire area.
54 The threshold for ice-bearing capacity (Fig.4) is given by the Gold’s formula L = 4x2, where
L is the load limit in kg and x the ice thickness in cm.54 The safe area is on the right, far
from the threshold, and is affected by a number of factors in addition to the ice thickness.
The risk factors include the pressure of water below the ice sheet, cracks, tidal cycles and
related exchanges with milder seawater, sudden temperature changes, snow cover,
vibrations in the ice sheet for the presence of people, repetition of loads and long-term
stress. As safety threshold, it is advisable to have 18 cm thickness throughout the whole
walking area, i.e. 1300 kg ice bearing capacity. We will see that Venetians risked walking
on unsafe paths, sometimes with tragic consequences.
Fig. 4
Threshold for ice-bearing capacity, i.e. load limit versus ice sheet thickness. The threshold is the black
line; the safe area is on the right side, shaded, except for a band close to the threshold limit.
55 The Venice authorities favoured safe walking paths with ice-bearing capacity to reach the
mainland. Volunteers and workmen organized by the City were summoned to check the
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ice slab. Most often people walked in strict processional order, thinking of taking
advantage of the involuntary check made by the preceding person. However, a long line
of walking people is extremely dangerous because repeated loads over the same area, and
within a short period of time cause, to ice fatigue and failure. The worst situation was
with resonant vibrations caused, for instance, by the Dance of Moors, described below.
Only in those cases that the thickness of the ice sheet exceeded in a high degree the
threshold for ice-bearing capacity, it did not break down and could endure the above-
mentioned heavy weight.
56 The configuration of the Lagoon changed over time. From 1324 to 1683 the rivers
entering the Lagoon were diverted to avoid the transport and deposit of mud and sand.
From 1960 some canals were excavated to deeper depths for tankers and cruise ships. In
the 18th century a massive dam was built to separate and protect the Lagoon from the Sea.
All of these works changed a bit the response of the Lagoon. Today the central part
(Northern Lagoon) is more protected against ice, while the Eastern part is more easily
covered with ice, as we have seen in winter 2012.
5. Evidence of harsh winters from written sources
57 The list of the very severe (VS) and great winters (GW) from written sources analysed for
Venice and Northern Italy is here reported. The bold date in the heading is the date
recognized for the harsh winter. As common in climatology, the winters are indicated
after the number of the year in Gregorian style, i.e. A.D. Winters with date followed by a
question mark ? are not adequately supported and in general should be rejected, as
specified. Notes or text reported in square brackets [ ] are our specifications added to
make the comprehension easier.
604 VS
58 The historian Paul Warnefried known as Paulus Diaconus (720-799) who lived in Aquileia
(100 km North East of Venice) wrote: “Blessed Pope Gregory died in the eighth Indiction of
the second year of Emperor Phoca. He was replaced by Pope Sabinianus. In that year the
winter was so harsh that it killed vineyards almost everywhere”.55 Sabinianus was elected
pope the 13 September 604, indeed in the second year of reign (602-610) of the Eastern
Roman Emperor Phocas.
609 GW
59 Paulus Diaconus wrote: “The seventh year of Phoca Emperor [i.e. 609].... In that year the
winter was so harsh that the sea was frozen over”56.
764 GW
60 Paulus Diaconus (who was contemporary) or Landulphus Sagax (who updated Paulus at
the end of the 10th century) reported: “In the 23 rd year of Emperor Constantine [i.e.
Constantine V nicknamed Copronimus, ruled 741-775, i.e. the year 763] ... The same year,
starting from October, a harsh and bitter cold was not only in our land, but even to East
and much more to North. Because of the severe cold, the sea water became hard as a
stone for over hundred miles and with a thickness of 30 cubits [1 cubit = 44.4 cm and 30
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cubits = 13.32 m. This thickness is not realistic]... 57 After a long and detailed description
of the situation in the East countries and the Bosphorus, the text reports that in February
the cold continued with an exceptionally abundant snow and floating ice slabs, like
icebergs “We ourselves were an eyewitness and with thirty companions went out onto
one of them and played on it. The icebergs had many dead animals, both wild and
domestic on them.” Exactly the same text is found in the Chronicle by Theophanes the
Confessor. The many and detailed references to the area of Byzantine influence suggest
that this text was written by Theophanes and copied by Paulus and/or Landulphus,
including the personal detail of having been witness and having plaid on floating
icebergs. The report was summarized by late authors who omitted the less credible
details: "Year 4,727 after Creation58 - Year 764 A.D. At the beginning of October the cold
became so extreme, that the Black Sea was frozen over for one hundred miles".59 “From
October to February the winter was so cold that the sea froze over hundred miles and
over thirty miles, the ice thickness was one cubit [1 Rome cubit = 44.43 cm] and it was
hard as stone. People walked on it as they were on solid earth. Snow was so abundant that
it formed mountains and exceeded 20 cubits [about 9 m]”.60 “In January and February the
winter was so harsh, both in the Western and the Eastern [European] countries, so that all
the rivers froze and in Constantinople, it was possible to go with carts over the sea”.61
Briefly, the cold was in the interval from October 763 to February 764; in October the
seawater temperature is too high to freeze, and the most likely period is January-
February, and February is suggested by the reference to the floating ice slabs.
853 GW
61 This event has been variously dated: 852, 853, 859, 860 and 864. The earliest existing
Venetian history, the chronicle of Johannes Diaconus of the 10th century, said: “852 AD:
Maurus [Businiaco or Busnago son of Geniano] was elected bishop of Olivolo [one of the
islands that formed the actual City of Venice, named in 1091 Castello] ... In that year such
a horrible freezing is mentioned at Venice, as never happened before nor will ever
happen again"62. This citation has been reported dated 852 by Moisè Giuseppe Levi,
Francesco Saverio Zanon and Arnaldo Segarizzi after Gallicciolli,63 who said: "An
enormous extension of ice occurred at Venice when Maurus was elected bishop of
Olivolo". According to Correr et al., Cessi and Cappelli 64 Maurus was elected in the
Gregorian year 853. In the Civic Museum of Padua a copy of the will of the preceding
bishop, Orso Partecipazio, is dated 853, so that the election of Maurus occurred in January
or February of the Gregorian year 853 that is 852 More Veneto. Moisè Giuseppe Levi,
Francesco Saverio Zanon and Arnaldo Segarizzi dated incorrectly this event 852 after
Giovanni Battista Gallicciolli who never specified More Veneto because he considered it
62 Giovanni Monticolo in his critical edition of the 'Chronicon' by Johannes Diaconus65
confused this event with another, which occurred in 860. He claims to quote the early
Medieval German historians, Einhard (770-840), who wrote the first part of theAnnales
Fuldenses: sive annals regini francorum orientalis66, and actually confused him with presbyter
Fuldenses Rudolfus who wrote the second part of the Annales in the 9 th century and was
contemporary to the event. Dating the event to 860, Rudolfus wrote: "The winter was
exceptionally severe and long; it caused much damage to farming and trees. The snow
was blood coloured. The Ionian Sea [a wrong term for the Venice Lagoon and the Adriatic]
was severely frozen because of the glacial cold. For the first time traders arrived at
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Venice riding with merchandise, instead of sailing.67 The mention of the reddish snow
preceding the freezing probably indicates a situation characterized by a northern flow of
polar air encountering the southern warm and humid Sirocco, which carries reddish dust
from Sahara. Since both the German Rudolfus in the late 9th century and the Venetian
Johannes Diaconus in the 10th century affirm that the event was so severe as had never
occurred neither before nor did it happen afterwards, only one of them seems to be
correct. Undoubtedly the Venetian Johannes Diaconus is more reliable than the German
Rudolfus, who was not very familiar with the geography and events in Italy. Probably
Rudolfus associated the very severe winter in 860 Europe with news of an exceptional
frost that occurred in Venice.68 Giuseppe Toaldo and Ludovico Antonio Muratori69, who
were often used as authoritative sources, also followed Rudolfus. Toaldo wrote: "Years
859 and 860 AD. The Lagoon was frozen and wagons reached Venice". Some doubt arises
whether: (i) the original source referred to two different winters, because the year 859
was missing in the Toaldo’s list of cold winters appeared in the 2nd edition; (ii) whether
the source referred to 860; in such a case the source was not Venetian because it had used
the More Veneto; (iii) Toaldo found two descriptions differently dating the same event.
63 Markus Fritsche70 in his Catalogue wrote: "Year 4,826 after Creation - 864 A.D. Winter was
long and vehement, much more than usual. Blood snow. The Gulf of the Adriatic Sea,
where Venice was founded, was frozen over. Merchants transported up and down from
the hinterland their supplies, with carriages and horses on the frozen marshes." Toaldo,
who relied on Fritsche said: "In 864 the Venice Lagoon froze again.”71 Easton72 reported
the winters 860 and 864, as they were two independent harsh winters, and for 864 relied
on Fritsche and Toaldo. Hennig73 quoted 860 and 864 as harsh winters in England and Low
Countries, citing some local sources.
64 To sum up, it is uncertain whether the date of the cold winter in Venice was 853 or 860, or
if that of 853 was very severe in Venice and 860 very severe in Western Europe. However,
we should note that the expression "as had never occurred neither before nor after" in
the chronicles is often found as a hyperbole and should not be taken literally. Very
probably, the harsh winter was only one, occurred from 853 to 864. In this context the
year 853 has the advantage of an early source with direct reference to Venice.
1119 GW
65 Available documents are late. Umberto Locati reported: "In 1118 the cold was extremely
severe, and for this reason the yield of the next year was extremely poor, and caused
famine over the whole of Italy"74. The Cronaca by Girolamo Savina (ca 1588) for the year
1118 reports: "The Lagoon was so hard frozen as to bear the weight of people riding on
horses. The frost killed vines and trees. Afterwards famine and mortality prevailed" 75.
Gallicciolli76 quoted Savina:A terrible frost. People rode over the frozen marshes.
Famine and mortality happened the next summer” and dated the event 1118 and then in
1122 quoting “various writers, ancient chronicle” with identical details but different date.
The harsh winter is also reported in the Cronaca by Friano degli Ubaldini77 (early 16 th
century), dealing with the same geographic area (Bologna), but dating the harsh winter
1119. These uncertain sources are generating a duplication of events. Francesco Saverio
Zanon quoted some unspecified Annales Breves (the event is missing in the Annales Venetici
breves 78), and dated the event within the time span 1118-1122.79 The most convincing date
is 1119 that fits with the dating styles respectively used in Venice i.e. 1118 More Veneto
(Savina) and in Bologna, i.e. 1119 More Romano (Friano degli Ubaldini).
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1127 GW
66 Four local chronicles: Annales Sanctae Trinitatis (12 th-13th century) Filippo Garbello, ca
1232; Giovanni Codagnello, 1235, Carlo Sigonius, 1575, and Friano degli Ubaldini, early 16
th century, who all relied on an unspecified source, reported that, when the Emperor
Henry [V] died [i.e. 1126], Frederick and his father Conrad with the army of Henry [V]
invaded Italy [...], The Po River froze, and supported the load of the invading army of the,
with horses and carriages, and the whole region suffered a terrible cold.80 Another
Emperor with name Henry (VII) has been found that invaded Italy in another occasion,
i.e. 1306, and he too found the Po River frozen. This generated some confusion and might
be suspect; however it is well documented before the next invasion in 1306. Toaldo
duplicated this event in his publications in 1770, 1781, 1797 but dated it to 1133.81
1157 VS ?
67 In the history of the Emperor Frederick, the German chroniclers Burchard and Konrad of
Lichtenau (13th century) wrote: “A.D. 1157. Very abundant snow and unusual cold in the
period of our Lord Passion. Great and extreme dryness summer for the whole summer”82
In his list of extraordinary events Markus Fritsche summarized (without quoting the
source): Year 5119 after Creation, 1157 A.D. Very abundant snow and unusual cold;
famine and dry summer followed it”83 After Fritsche, the event was reported by later
authors. We note that in 1157 Easter fell in March 31st: snow and cold were the last week
of March, i.e. too late to form ice on the Lagoon or the main rivers.
1216 GW
68 Several chronicles of the Po Valley reported that the Po River was frozen for two months
and the wine froze in the caves.84 The dates are: 1211, 1214 and 1216, two of them (1211
and 1216 by Sigonius). No specific documentation was found for Venice. As Codagnello
wrote in 1235 and is credible, we accept the Codagnello's dating and reject the other dates
(misprinted or duplicated).
1234 GW
69 This great winter is mentioned by several chroniclers. Two manuscripts explicitly deal
about Venice: the Codice Gradenigo and the lost Manuscript Svajer 865. "The Lagoon froze.
The ice resisted people going on foot from Venice to the hinterland."85 The text of Svajer
has been reported by Gallicciolli and Zanon86. Gallicciolli read the manuscript and dated it
1233 (probably More Veneto); Zanon relied on Gallicciolli and dated it 1234 A.D. The severe
frost of this winter was mentioned by several chroniclers between the 13th and the 18th
centuries who indicated that the Po and other rivers of northern Italy were frozen over,
the wine was frozen in barrels, trees killed etc, with some uncertainty of dating, spanning
from 1230 to 1235, as follows: 1230 is supported by sources, i.e. Giovanni V. Gandolfi (14th
century) and Elia Cavriolo (16th century); 1231 by Francesco Maria Guidotti (ca 1521); 1232
by Umberto Locati (1564); 1233 by 3 sources: Bernardino Corio (1474); Lodovico Vedriani
(1666-67); Donato Calvi (1676-77); 1234 by 25 sources: Annales Sanctae Iustinae (ca 1270),
Chronicon Marchiae Tarvisinae et Lombardiae (ca 1270), Annales Marbacenses (ca 1375),
Chronicon Patavinum (ca 1399) that reports: “1234. The winter was extremely harsh;
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vineyards, olive and all other fruit trees were killed. Most chicken and domestic animals
died. Waters were frozen that could bear people and horses going to Venice”, Ramponi
(1450), Matteo Griffoni (1472), Giovanni Agazzari (15th century, winter dated 1233 but
Incarnation style), Pompeo Vizani (1546), Cherubino Ghirardacci (ca 1568), Carlo Sigonius
(1584), Girolamo Rossi alias Hieronimus Rubei (1589), Giorgio Piloni (1607), Guglielmo
Schiavina (ca 1617), Cristofaro Orefice Saraceni (1619), Cesare Clementini (1627), Antonio
di Paolo Masini (1650), Pier Maria Campi (1651-52; winter dated 1233 but Incarnation
style), Lodovico Vedriani (1666-67), Compendio istorico del dominio e governo della città di
Ravenna (17th century), Grasulfus de Grasulphis (17th century), Girolamo Della Corte (17th
century), Cronica Gradenigo (18th century), Cronaca di Ravenna (18th century), Gallicciolli
(1795, relying on Manuscript Svajer No 865), Benedetto Fiandrini (1796); Christmas 1234
and January 1235 only by Gerolamo De Borselli (ca 1497). This winter was extremely cold
in most of Europe and was reported by Arago, Hennig and Easton 87 although with various
dating, determined by their uncontrolled sources. In conclusion, the best supported date
is 1234, that better fits the criteria discussed in Section 2 for the clear and coherent
description, the independency of the earliest sources, some of them in the living memory
of the event.
1306 GW
70 A number of chronicles mention a harsh winter with rivers frozen over from 1303 to 1306,
as follows. Friday, January 11th 1303: some people told me that the Arno River was frozen
over and people crossed it walking 88; 1304: the Po River froze, and carried the army of the
Emperor Henry [VII]89 1305: the end of the winter was very harsh90; February 1305: very
abundant snow91; 1306: Extreme cold for thirteen days in Parma and the Lombardy. All
the rivers including the Po River were frozen over and in several parts it was possible to
cross them on foot; boats could hardly move 92 ; rivers were frozen over and both foot and
horse passengers and wagons too travelled over the ice.93 The winter was extremely
severe and almost all rivers in Italy were frozen over, including the Adige River in
Verona. It was possible to cross it on foot, on horses, or with wagons; many trees were
killed. 94 In conclusion, the winters 1303, 1304 and 1306 fit the characteristics of GW. The
date 1303 is supported by a contemporary author, although not eyewitness, with internal
matching of day of the week (Friday) and date (January 11th 1303). It is not specified
where the Arno River was frozen (e.g. in the mountain area?), and this fact is not
confirmed by any other Florentine sources. Probably 1303 was a severe or very severe
winter. Winter 1304 was cited by Giovanni De Cornazzano who related the events to the
passage of the army of the Emperor. He made some confusion because Henry VII had
invaded Italy in 1310 so that the winter should be moved to 1311. However, 1311 is not
confirmed by other sources and should be rejected. Winter 1306 should be classified GW
relying on a contemporary chronicle and two late compilations.
1319 GW
71 A contemporary chronicle in Northern Italy reports: “Increasing cold from January to
February. The Po River, the wine in barrels, wells and springs were frozen. Many trees
were killed. Thursday February 20th strong and very cold wind; people could not walk on
streets and who was there was killed. Snow and ice lasted till March, and even more in
the shade. Wood became very expensive and was permitted to hunt pigs and other
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animals to survive. Streets were covered with half an arm [i.e. 34 cm; 1 Venice arm = 68.3
cm] thick ice slab.”95 “The cold was extremely intense. The Po River was frozen over for
several days. Bread was hard and it was impossible to eat it without melting it on the
fire.” 96 “Year 5280 after Creation; A.D. 1318. Extreme frost, winter very harsh.”97 No
specific documents regarding Venice have been found for further details.
1341 VS ?
72 We have late quotations, not specific for Italy. Marcus Fritsche wrote: “Year 5303 after
Creation; A.D. 1341. The cold was so intense in this winter, that people in Livonia [Baltic
region] had lost nose, fingers and so on for the cold”. 98 Toaldo, without quoting the
source: “1341. Very harsh winter.” 99 We haven’t found further support to confirm this
event in Italy.
1355 VS
73 The harsh winter with snow, long lasting ice and all rivers frozen over (in particular the
Arno River) in the Florence region is mentioned by the witness Matteo Villani100 who
dated 1354 but used the Incarnation calendar, Florentine Style. No documents have been
found about Venice.
1358 VS ?
74 “1358. Very dry and very cold winter.” Toaldo101, without quoting the source. We suppose
that this may be a duplication of winter 1355.
1396 GW
75 Clemente Miari, who wrote his chronicle between 1383 and 1412 and probably was an
eyewitness said: “On January 22nd it was possible to reach Venice from San Giuliano [in
the Venice hinterland], walking and riding on the frozen Lagoon. We did it with eleven
1408 VS ?:
76 “1407. Winter extremely cold; the year was nicknamed the year of ice”.103 “Harsh winter,
with frozen rivers and lakes” according to late 18th and 19th centuries historians, who did
not specify their source.104 The event is not adequately supported by contemporary
1413 VS
77 "Severe cold and bad weather. Numerous death incidents”,105 according to the Venetian
historian Marcantonio Erizzo, who wrote 82 years later.
1419 GW ?
78 “The winter was exceptionally harsh. All rivers were frozen, and it was possible to cross
them on foot or with pack animals and even with wagons. Vineyards were destroyed and
next year there was scarcity of wine. It was possible to cross the sea and reach Venice”.106
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The event is quoted by a late source and is not supported by other sources. Maybe a
duplication of 1413, but with some additional emphasis. This winter should be rejected.
1432 GW
79 "Beginning on January 6, 1431, the frost was so terrible at Venice, and the ice was so
extensive, thick and hard, so that it was possible to go from Venice to Mestre over the ice
sheet. A cart drawn by a horse arrived at Venice from Mestre to carry a bride from Venice
to Mestre. The ice lasted till February 22nd."107 Erizzo wrote More Veneto and,
consequently, Levi, Zanon and Segarizzi108 incorrectly dated to 1431 without considering
the time difference.
1441/2 VS and 1442/43GW
80 A series of chronicles span from 1441 and 1443, explicitly mentioning December. This
makes particularly difficult to distinguish between the two years and the risk of
duplications. A cold 1442 winter (no month specification) with abundant snow and the Po
river frozen and supporting people and carriages is mentioned by Cherubino Ghirardacci
(1568), Guglielmo Schiavina (ca 1617), Cristofaro Orefice Saraceni (1619), Compendio
istorico del dominio e governo della città di Ravenna 17th century and the Cronaca di Ravenna
(end 18th century). Abundant snow and extreme cold starting from December 24th 1442
and lasting for three months is mentioned by Marco Antonio Bianchini 1513109. The
contemporary Cattanio de’ Cattani specifies: “[1442/43]: This was the second year of ice.
The Po River in Ferrara was frozen over, supporting carriages with horses … In Venice the
Grand Canal was also frozen, and people and animals could go from Marghera to Venice
[crossing the frozen Lagoon]. Several vineyards and trees were killed …” 110 Two
contemporary Anonymous sources, i.e. Cronica di Bologna and Diario Ferrarese,111 conveyed
a similar report. One hundred years after the event, the Venetian historian Marino
Sanuto without quoting his sources wrote: "The Lagoon froze in December [1442] and the
ice held the weight of people walking from Mestre to Burano Island. The same occurred in
1475, 1476 and 1490. It snowed continuously for 12 days."112 Other chronicles from the 16
th to the 18th also reported on this winter, however, without indicating their sources.113
The conclusion is that two consecutive harsh winters occurred: the winter 1441/42 could
be classified severe to very severe, and the 1442/43 was a great winter. The accurate
history book by Cardinal Cesare Baronio reported: “Year A.D. 1441, [Pope] Eugenius IV
[year:] 12, Friederick III [year:] 3, Johannis VII [year:] 24. At the end of the year, from
December 7th to February 7th the cold in Lombardy [region some 200 km West of Venice]
was so extreme that the Po River was frozen over and supported horses and carriages. In
the region of Ferrara [some 100 km South West of Venice] people organized a banquet on
ice and this feast was crowded. The snow was so abundant as never occurred in living
1477 VS ?
81 According to Bernardino Zambotti, who wrote 34 years after this winter, extreme cold
was from October 1476 to March 1477. In 1477 the Po River froze and it was impossible to
grind wheat.115 However, no further support has been found. Probably the winter was
severe with a local problem of ice in shallow channels used to bring water to mills, or this
is a duplicate event; see 1487?, 1491.
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1487 GW
82 "An exceptionally heavy snowfall occurred on Christmas night [December 25th 1486] and
it continued snowing for a month. On the mainland all the vines died. People rode from
Marghera to Venice over the thick ice. The mayor of Mestre arrived in a coach as far as
the island of San Secondo. (...) Wherever man looked around Venice, snow could be seen.
The canal between Piazza San Marco (the heart of Venice) and Giudecca [an island
directly in front of it] froze, and the people could cross on foot the canal without risk.
Boats were drawn from one bank to the other with a hawser." The text, very similar to
the description made by Cardinal Pietro Bembo for 1491, was reported by Secondo
Lancellotti, but dated 1492116, and Gallicciolli, relying on obscure Ancient Chronicles'117;
finally in the 20th century Zanon, who relies on an undated chronicle, Cronica Marciana,
kept in the Marciana Library at Venice.118 However, the severity of the winter is not
confirmed by other independent sources outside Venice and is very probable an error by
Gallicciolli or his documents. We are forced to reject this event that very probably is a
duplicate of 1491.
1491 GW
83 This winter is documented by tens of sources outside Venice and some specific of Venice,
here reported. A chronicle contemporary to the event, the Cronica de Venexia, reports: “In
1490 [More Veneto] on January 10th Venice was frozen so much for the extreme cold that
people and animals with food could cross the Lagoon from Venice to Marghera, i.e for
three miles of ice above the marshes119. The Venetian humanist and historian cardinal
Piero Bembo, who was eyewitness when he was 21 year old, wrote: "Winter 1490 [More
Veneto], was terrible, cold and long, especially because of the snowfall. All the Lagoons
around Venice were frozen. People came from the mainland safely on foot and on
horsebacks bringing provisions to Venice. The mayor of Mestre arrived in coach to San
Secondo Island, located in the middle of the Lagoon. Some riders jousted with lances on
the Grand Canal, where only large ships usually go. The water was frozen because of the
terrible cold and snow".120 The text of Bembo was famous and summarized by late
chronicles: Codice Gradenigo (18 th century) and Gallicciolli 121; in addition it was
misleadingly quoted by Toaldo who dated to 1492 122 and Zanon to 1490 123 creating
duplications. Other sources deal about this extreme cold in Italy, with the main rivers
frozen over and supporting people and carriages, wine frozen, trees killed.124 Some of
them report about Venice, and Jacopo Rizzoni in particular mentions that some wolfs
arrived in Venice crossing the ice 125.
1503 VS ?
84 This winter is found in late collections, e.g. Lancellotti who was used as a secondary
source. “In the time of Pope Julius II, who was sitting in 1503, the winter was extremely
cold, and the Po River was frozen over. The ice was so thick that the artillery with guns of
the Pope could cross it”126 Lancellotti relied on an obscure quotation "P. Iou. Lib.2 vit". In
reality, Lancellotti wrote that this winter happened in the time of reign of Pope Julius II
della Rovere, i.e. 1503-1513, and 1503 is only the date of its election. The problem is that
in the side gloss heading Lancellotti wrote 1503 as reference. Therefore the date 1503 is
misleading and the information should be referred to 1511.
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1511 VS
85 A number of chronicles of the 16th century, such as: Niccolò Seccadenari and the famous
historian Francesco Guicciardini127 mention severe cold, and the most relevant was that in
January the Po River froze (not specified where), and that it carried the weight of Pope
Julius' II army that was engaged in the siege of Mirandola, 158 km South-West of Venice.
Very probably, the winter was severe to very severe; we, however, suppose that in Venice
it did not reach the GW severity level, for the lack of local records confirming ice.
1514 SW ?
86 Jacopo Rizzoni128, an eyewitness living in Verona, some 120 km West of Venice, reports
that the Adige river was frozen over near a bridge, and people crossed it on foot. No
chronicles mentioning ice on the Po River. The contemporary Sebasiano Mulione129, living
in Gemona some 130 km North-East of Venice, mentioned three windy and extremely cold
days in February 1514. The contemporary sources in Venice do not mention anything that
may be related to a particularly harsh winter. The most probable classification is
“severe”. The winter was described with GW characteristics in late and not adequately
justified sources. Quoting the Manuscript Svajer No. 865 (end 17th century), Gallicciolli
and Zanon 130 reported: "The Lagoon was frozen from Fusina, [on the mainland, North-
West of Venice], to San Giorgio Island [in front of Venice]”. Arago mentions that the
winter was very severe in the Flanders, with carriages crossing the iced water bodies131.
Gallicciolli quoted 1514, and its general use is More Veneto, so that the winter should be
1515. Easton in the 20th century relies on 11 sources about this winter in Europe but with
date spread from 1513 to 1515. In particular, he quotes “1515: Thames frozen and used as
a highway. Carriages passed over on the ice from Lambeth to Westminster (W.
Thornbury)” without further details about Thornbury and the dating style.132 The same
quotation is in Lamb133. The event is not adequately supported, at least for Venice.
1549 GW
87 The winter was described by the contemporary Tommaseo De’ Bianchi nicknamed
Lancellotti, living in Modena, 150 km South West of Venice. “Extreme cold started the day
of St Sebastian [20 January] with ice, strong wind and dry snow. Thursday 22 some people
arrived from Venice told me that the ice covered the Lagoon for three days and it was
possible go from Venice to Marghera [on the hinterland] on foot. Boats were kept
outside134. The Venetian Girolamo Savina in 1558 gives an account of the situation: “in
January 1548 [More Veneto] the cold was extreme, with a lot of ice. The canals were frozen
over and it was possible to go from the Giudecca [island] to [St] Baseggio [on the Southern
Venice border, i.e. it was possible to cross the Giudecca Canal] walking on ice. It was
possible to reach the hinterland because all canals were frozen. Six persons inside a ship
trapped in the ice were dying for the frost. Two Greek men reached them and brought
them back, but this was useless. They [i.e. the Greek men] were rewarded with two ducats
135 each one.” 136 This fact was also reported by Cesare Clementini in 1617 who quoted
Valerio Monticoli, a chronicler in Ravenna137 . The famous architect Vincenzo Scamozzi
who was working in Venice in that time was eyewitness and confirmed the extreme cold
and impressive ice138, dating 1548 [More Veneto] i.e. 1549 [More Romano].
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88 Late chronicles too reported the event. Della Corte 139 reported about vineyards, olive and
other trees killed in the hinterland. Gallicciolli quoted the Manuscript Svajer 865: “1549.
The Lagoon froze, including the Giudecca canal as far as Murano” 140. The manuscript was
evidently written More Romano because the date is 1549. This is misleading because
Gallicciolli normally uses the More Veneto and who reads Gallicciolli is induced to move to
1450. Levi141 relied on the Manuscript Svajer 865 and the text is identical to Gallicciolli.
Zanon quoted an unknown source: “The frost began on January 21st, 1548 [More Veneto];
the canals crossing was made with boats drawn to and fro with hawsers over ice. People
went on foot from the Zattere [Southern side of Venice] to the Giudecca [island facing the
Zattere] (Cristoforo Zaccaria)”.142 Then he continued reporting and quoting the above text
by Savina. After he reported as a distinct event for the next year: “1549. The Lagoon froze,
including the Giudecca canal as far as Murano (Ms Svajer No 865)” making a duplicate for
the More Romano used in the source.
1560 VS
89 Umberto Locati, living in Piacenza, mentions that the Po froze over and dated the event
to 1559 [Incarnation Style used in Piacenza, i.e. 1560 A.D.].143 A late 17th chronicle mentions
a harsh winter in 1560, without indicating the source.144 Quoting the 15th century
Manuscript Svajer 421145, now lost, Gallicciolli wrote: "1560 January. Snowfall continued
for 3 days and the canals were frozen over. (Ms Svajer 421)”146 Very likely, the Ms Svajer
421 is based on the More Romano.
1577 VS
90 The contemporary Codex Cicogna 147 reports: “A terrific cold happened this year, that
exceeded the limits of the nature and the climate. The Doge Mocenigo died after having
ruled for eight years and six months…” The Doge Alvise Mocenigo ruled from 1570 to
1577. The Codex Cicogna 262 was misdated 1567, and we should assume 1577.
1581 GW
91 The famous architect Vincenzo Scamozzi, active in Venice, mentions that he was
eyewitness of the Lagoon the frozen over in 1581, 1594 and in 1607, when the northern
winds brought an exceptionally severe frost to Italy and part of Europe, and it was
possible to cross on foot the ice sheet formed on the Lagoon and the canals and to safely
reach the Giudecca, Murano and other islands. In addition, he specified that in the above
events the low rate tidal exchange was crucial for the formation of the ice sheet. 148
1594 GW
92 Vincenzo Scamozzi claims of having been eyewitness of this event as well (see winter
1581). The frost was reported by the contemporary Cesare Campana (living in L’Aquila,
Central Italy), who was the source for Secondo Lancellotti. In turn, Lancellotti was the
major source for Toaldo 149. Campana wrote: “1594 exceedingly low cold in Italy. The
winter was dry, long and extremely cold. Not only rivers, but the Venice Lagoons too
were frozen over for several days, and citron orange and other fruit trees, although
located in mild regions became useless”150. Lancellotti quoted: "In Flanders, the Rhine, the
Scheldt and other Rivers were frozen over; in particular, in Italy the Venice Lagoons were
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frozen. (Caes. Camp. 15)." 151 The same text was reported by Tilloch152. According to Arago
and Hennig153 (who relied on Lancellotti , Toaldo and probably Tilloch), the Rhine and the
Po Rivers froze. The sea was frozen over in Marseille and in Venice.154 Easton155 dates this
event to 1595. However, since the late authors rely on a number of uncontrolled
documents they provide inaccurate dating.
93 The dating is according to 18th and 20th centuries sources that cite the Manuscript Svajer
No 865 that reports on the public prosecutor's, Francesco Zorzi, who died due to the
intense cold while crossing the ice sheet from Torcello Island to Venice.156 According to
Serafino Pasolini and Benedetto FiandriniThe horrid cold of this winter killed in
Ravenna (100 Km. South of Venice) many people, animals, vineyards and trees”157. Both
authors, however, do not indicate the sources they used. In addition, this winter is not
recorded by two key persons living at that time that should have mentioned it. The first
was Giovanni Stringa who updated from 1581 to 1604 the Francesco Sansovino's book
adding a number of climate-related events 158. The second key person who missed this
event was Vincenzo Scamozzi.159 One might suppose that Scamozzi missed this frost
because from 1596 to 1601 he was working outside Venice, at Padua and Vicenza.
However, these two cities are close to Venice, with the same climate and it is very
unlikely that passed unobserved. Briefly, this frost is not supported by two key local
contemporary sources interested to climate. We should conclude that 1598 is a duplicate,
possibly a misprint for the well documented 1594.
1603 GW
94 "Beginning on February 2, 1602 [More Veneto], the Lagoon and all the canals in Venice
froze over for 8 to 10 days." This event was added by Giovanni Stringa in the 2nd
posthumous edition of the Sansovino's book, compiled in 1604.160 The date was misprinted
1601 by Gallicciolli, and the error was transmitted to Levi, Zanon and Segarizzi. 161
1608 GW
95 Scamozzi, who may have been an eyewitness, mentions that in February 1607 the Lagoon
and all the canals were frozen by an exceptionally cold wind from North combined with a
modest tidal range, and that it was possible to reach on foot the Giudecca, Murano and
other islands162. Giustiniano Martinioni that updated in 1663 the 3rd edition of Sansovino's
book wrote: "After the beginning of this year (i.e. March 1608), the winter was unusually
severe. Due to an exceptional snowfall, it was impossible to walk in the streets or go out
through the door".163 In the late 18th century Toaldo reported the severity of the winter
and the exceptional snowfall.164
1621-22 GW?
96 Tilloch,165 later copied by Millner166, and followed by Arago and Easton, reported: "In 1621
and 1622 all the rivers of Europe were frozen, and even the Zuidersee [the Netherlands]. A
sheet of ice covered the Hellespont; and Venetian fleet was chocked up in the Lagoons of
the Adriatic." Arago167 wrote the same, almost with the same words, except for the winter
1720-21, and adding the Baltic Sea and the Provence, and disregarding the Hellespont. He
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specified that he relied on Sethus Calvisius.168 Hovewer, the book by Calvisius was
published some 20 years before the event that is obviously missing. Consulting the next
posthumous editions of this book, we found the third edition updated by J. Zhym and
published in 1629, almost contemporary to the event, that reports: “1621 AD. The cold
was very intense for the whole month, and a part of the Baltic Sea was covered with a
thick ice sheet”. 169
97 However, Venice and the Adriatic Sea are not mentioned. Furthermore, although this was
a well-documented period, no confirmation has been so far found, except for some snow,
cold and ice in Modena in 1621. 170 Giuseppe Toaldo, in his list of the cold winters includes
1624 and 1625, but without notes or comments, or specifying where in Europe or Italy as
he did when he found some precise information171. The dates 1621, 1624 and 1625 should
be considered misleading, misprint or duplication of other events and should be rejected.
1637 VS ?
98 Only Giambatista Biancolini, a chronicler who one century after this winter updated the
chronicle of Verona by Pier Zagata, mentioned an intense cold: “For the intense cold the
Adige River was iced from the chain172 of Victory [a gate in the city walls] to the chain of
St Zeno [another gate]”.173 Easton and Hennig174 did not mention this winter at all. In the
contemporary chronicles in Northern Italy no mention has been found that may justify a
severe winter in Venice and the winter should be rejected from the list.
1638 VS
99 This was a renamed harsh winter in Marseille, on the southern coast of France. The
astronomer and philosopher Pierre Gassendi working at the University of Aix-en-
Provence was a witness and ten years later recorded [in Latin] the weather and
astronomic observations in his daily log. The most interesting comments are: “Day 30
[December 1637]. Clear sky in the morning; the cold was very intense. At 6 p.m. some
snow, then again. … Day 31. In the morning sky mostly clear, but cold extremely intense,
snow very cold and then becoming compact like ice. … Year 1638, month January, Day 1.
Sky mostly clear and always very intense cold. Day 2. Clear sky in the morning and
always very intense cold. … At noon cloud cover, with tendency to melt, but snow in the
evening. Day 3. Snow again but rain too, and for this reason much of the snow was
melted. Day 4. Weather lost it chill and almost all the snow was melted. … Day 15. All day
rain. Day 16. Chorus Wind [from North West] very cold. Day 17. Cold very intense, but no
wind. Day 18. Some cold, but sunny day till sunset. Day 19. Cold a bit attenuated. Day 20.
Cold was worsened and the wind blew stronger, and prevented from the traditional
procession of St Sebastian. Days 21 & 22. The air was cold enough. Day 23 Cold very
intense and Chorus Wind very strong. Day 24, evening. Wind blew very strong and
entering everywhere; the cold was beyond living memory. … Day 25. Always strong wind
and very intense cold. Day 26. The same. These days should be remembered for people
lemon, fig and olive trees killed by cold. The [water] in the port of Marseille formed ice
around vessels, etc. Day 27. Less intense wind and cold. Day 28. Wind and cold over.” 175
100 One and half century later, the same winter is found described at increased severity level:
Abbot Jean Pierre Papon, member of the Academy of Marseille, in his history of Provence,
wrote without quoting the source, very likely Gassendi: “1638. The Count of Alais arrived
the first days of January… In that period the winter was very severe and the water of the
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port of Marseille froze around the galleys”.176 The text by Papon was copied by several
chroniclers and historians, including Arago, Joseph Mathieu and Marius Villard177 and
became famous, while Gassendi remained almost unknown. Surprisingly, Easton178 wrote
that this winter had no comments except for Papon (he missed Gassendi) and Hennig179
had no sources for this winter; as a consequence, he considered it normal.
101 In Marseille the cold was intense and even extremely severe for some days, i.e. from
December 31st to January 2nd and then from January 16th to 26th. The first period, i.e. three
days, was too short to cause severe consequences, but the second period of ten days was
long enough and needs to be clearly interpreted. It is not clear whether the whole port
was frozen over (that requires a long period of very intense cold), or only some ice was
seen on the keel side above the waterline for frozen splashes (that is possible in a
relatively short period of intense cold). In effects the text does not quote “the water in
the harbour was frozen over and the galleys were chocked up”, but “the water froze
around the galleys”, i.e. the galleys were covered of ice, not the sea. An example of the
second interpretation is given by the gondolas with ice in February 1929 (Fig.5).
102 The weather log by Gassendi suggests a flow of arctic or polar air crossing Europe and
entering the Mediterranean close to Marseille, being channelled by the Pyrenean and the
Massif Central mountains. The persistence of the circulation is generally due to a blocking
high-pressure over Scandinavia. If the pressure pattern brings a violent flow of very cold
air, the same situation is found in Northern Italy.
103 In Italy, the late chronicler Giovanni Romani quoted a contemporary act of notary E. Lodi
that in the winter 1636 the cold was severe with ice slabs on the Po River and several
vineyards damaged or killed; in 1637-38 some vineyards were damaged or killed again180.
In other words, the winter 1638 was not worse than 1636. We have consulted several
contemporary documents in Northern Italy, with several detailed notes, but no mention
has been found that may justify a very severe winter in Venice. The circulation caused
severe problems in Southern France, but was not strong enough to enter Northern Italy
and reach Venice. For this reason in Marseille the winter was a GW (if the seawater in the
was frozen over) or a VS winter if only the keels were covered with ice; however, in
Northern Italy this winter left no memory of it.
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Fig. 5
Gondolas with iced keel, in February 1929, S. Marco quay, Venice.
Photo by Anonymous in Zanon, 1929
1658, GW ?
104 In 1820, Alexander Tilloch wrote: “The winters of 1658, 1659 and 1660 were intensely cold.
The rivers in Italy bore heavy carriages; and so much snow had not fallen in Rome for
several centuries. It was in 1658 that Charles X of Sweden crossed the Little Belt over the
ice from Holstein to Denmark with his whole army, foot and horse, followed by the train
of baggage and artillery”181. Thomas Millner copied the same text.182 Arago183 reported the
story of Charles X, the snow in Rome, and very severe cold and ice from December 24th
1657 to the end of February 1658, when the Seine River outflowed. However, no mention
of frozen rivers has been found in Northern Italy sources and the fact should be rejected.
The foreign sources refer to France and other northern regions far away from Venice that
remained unreached by the polar air circulation.
1684 VS
105 One hundred years later, in 1796, Benedetto Fiandrini wrote: “1684. This year the winter
as so harsh that all wells were frozen over, not only in Romagna, but everywhere in
Italy” 184. Serafino Pasolini wrote substantially the same, but added that many animals
and vineyards were killed by frost. 185
106 "In January 1684 the Lagoon froze. It snowed continuously for 10 days. The frost killed all
the vines and many people". This event was reported by Gallicciolli,186 who quoted:
Ancient Chronicles”. Surprisingly, he dated this and the next two events according to the
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More Romano probably used by the source instead of the More Veneto that he hitherto used.
It should be noted that in the same year 1684, the Thames River froze in London. In other
words, the frost extended over most of Europe.187
1709 GW
107 This was one of the most severe winters of the last millennium, supported by hundreds of
sources. We have selected the following five descriptions, made from eyewitness and
others scientists who lived not long afterwards.
108 The Venetian senator Pietro Garzoni, who was eyewitness, reported that Fredrik IV, king
of Denmark, arrived in Venice at the end of the year 1708 [More Veneto that means
January or February 1709]. A welcome programme was prepared with great festivities to
be held in his honour, especially because the period was Carnival. However, not all the
planned festivities were possible because of the extremely severe cold. "The cold severity
exceeded the thresholds established by the nature and the climate. All the internal canals
and the Lagoons became petrified by cold, and boats could not move. Boats transporting
food and supplies for the survival of the City were moved with pickaxes used to the best
of the power of the Arsenal workmen"188
109 Cronica Gradenigo: “In 1708 [More Veneto], during the king's of Denmark stay in Venice
when Alvise Mocenigo was the Doge, an extreme cold started in the Epiphany day [i.e.
January 6th]. Many people were killed by the cold, and the Lagoons were frozen over with
thick ice that carried people, horses and carriages from Mestre [in the hinterland] to
110 Gradenigo's Annales were similar but dated it to the "the night of January 5th, 1708 [More
Veneto]" 190.
111 “The 6th January 1708 [More Veneto] the horrible cold started. The Lagoons were frozen
over for about 18 days. Food supply was made with carriages. Similarly in 1740, 1758 and
112 The contemporary Giuseppe Riva, living in Modena, reported: “January 26, 1709. We
received news from Venice. They mention that the cold of this winter exceeds any other
one could remember for the last 25 years. All canals are frozen over and there is a risk
that all business and transport of supplies will stop”.192
113 “The year 1709 was famous for the severe frost and the Venice Lagoons frozen over,
holding people walking on ice. Heavy snowfall everywhere, which caused to severe
famine. Frost and snow lasted till the end of February, and it was impossible to transport
burning wood, crops or other supply with carriages. March was followed with epidemic
and illness, and many people died”, according to late 18th century Palladio degli Olivi.” 193
114 “The frost was so severe that both the Venice Lagoon and the Po River were frozen over.
It was possible to safely cross the river with carriages, and artillery. The ice on the Lagoon
was noxious to Venetian trades because transports were necessarily on ice, and were
more difficult that using boats. Vineyards, olive, nuts, orange and lemon groves and other
trees were killed.” 194
115 “1709: The famous cold”, the synthesis by Giuseppe Toaldo.195
116 Unfortunately, no temperatures of this winter were recorded, although Giovanni Poleni
at that particular time used in Venice an Amontons' thermometer196 to measure this winter.
197 Forty years later, Biancolini' Chronicle, written at Verona, 80 km West of Venice,
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reports that “the extreme cold began on 6th January and killed several trees and
especially vineyards and olive trees. The thermometer invented by Mr. Réaumur of the
Science Academy, Paris, dropped to fourteen degrees below zero”. 198 The level -14 °R=-18°
C. Nevertheless, Biancolini did not specify when and where the observation was made
(e.g. Verona? Paris?), thus making uncertain his information.
1716 VS
117 The Venetian eyewitness Antonio Benigna wrote a book of his memories, from 1714 to
1760, where we read: "17 January 1715 [More Veneto]: People reached Venice from Mestre
crossing the ice, bringing animals and other supplies. This until 20 January.Gallicciolli
wrote: “In January the cold was not less severe than in 1709, but was shorter. The Lagoons
were frozen over”.
1740 GW
118 In late 18th century Gallicciolli wrote: "the same as for 1709".199 The severe cold and its
duration are confirmed, as discussed later, by the instrumental readings.
1755 GW
119 In his book of memories, Antonio Benigna wrote: "On January 1st, 2nd, and 3rd, 1754 [More
Veneto] there was severe frost; on the 4th, 5th, 6th and 7th the frost was even more severe,
fresh wind blew and ice developed on the Lagoons. On the morning of the 8th the wind
dropped, and the Lagoon was fully frozen over. Afterwards the weather was milder.
However, on the 9th two soldiers came from Mestre on foot and 6 persons went on foot
from Venice to Mestre and returned the same way with muttons. On the 11th a public
procession carrying the Virgin took place at St Marc Square, praying for rain. People
went from Mestre over the ice, transporting food supply. On the 21st, 22nd, and 23rd fresh
wind blew again. On the 24th the wind dropped and on the evening of the 25th, the Lagoon
was once again covered with ice. The weather was fine but very cold, especially at the
beginning of February. On the 4th and 5th the Lagoon was frozen over again and the canals
in Venice too. On the 6th, light snow fell during the night. On the 7th, the ice melted and
the Sirocco wind blew for the next days. On the 13th it rained. On the 18th, the ice
120 A long letter by an Anonymous eyewitness, dated February 5th, 1754 [More Veneto], 201
described in detail the supply of food when the Lagoon was frozen. The ice appeared on
January 6th and lasted for eight days; then it started to melt, disappeared and afterwards,
returned again. The author says that he has measured the temperature with his
thermometer and that the air temperature of the second period was the same as in the
first period (6th-14th January), without specifying the degree.
121 Another contemporary said: “January 8th 1754 [More Veneto]. There was severe frost and
the Lagoons, the internal and the external canals were frozen over. This caused shortage
of burning wood and water. The sky was clear. Workmen were sent from the Arsenal to
cut the ice slab”.202
122 A weather log with daily instrumental observations and notes, made in Venice by the
scientist Tommaso Temanza, a former pupil of Giovanni Poleni, reads: "January 6th:
extensive ice on the Lagoon. 13th: sky less clear and ice is melting. 24th: sun and clouds.
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Once again ice covering the Lagoon. February 6th: ice is melting". The observations
included: Moon phase, air pressure, temperature, thermometer, tide, state of sky, wind
and rain.203 However, the temperature is not easily understandable, because Temanza
used an Amontons thermometer with unknown calibration, and the readings are expressed
as derived from the average temperature in Venice. It might be possible to reconstruct
the scale by comparing to the contemporary series in Padua; however, such a study would
require a very long time, not fully justified since it would not add much to our knowledge.
123 Unfortunately, a number of persons, including the above-mentioned Temanza, used their
own personal thermometer scale that did not display the actual temperature at Venice.
However, we know the temperature from the measurements taken in Padua by Giovanni
Poleni and Giovan Battista Morgagni (see later).204 We should note that the temperature
in Padua dropped to -7°C on January 10th and -6.5°C on February 5th; Padua is near to
Venice and the temperature is similar, i.e. within ±2°C.
124 Relying on Temanza, Toaldo wrote 45 years later: “Year 1755: In January the Lagoon was
twice frozen over. The ice held the weight of people. Temanza measured the ice thickness
and it was found to be 15 Venetian inches, i.e. 43 cm (1 Venice inch= 2.898 cm). No snow."
205 An ice sheet 43 cm thick may bear up to 7500 kg.
125 The velocity at which ice was formed on January 6th was impressive. All the canals were
frozen over in a few hours. Initially the Lagoon was rough because of the strong wind. In
the marsh areas, where water was shallow and colder, the ice slab kept the form of waves.
We cannot know whether the water had formed so many freezing nuclei that determined
an instantaneous transition, or the rough appearance was simply determined by wind
driven water splashing on already formed ice and then building-up illusion of waves. The
thickness of ice was two Venetian feet, i.e. about 70 cm (1 Venetian feet = 34,77 cm). It
should be noted that this thickness is almost twice as much as the measurement taken by
Temanza; however, this difference can be explained by the location and the time the
measurements have been taken.
1758 GW
126 Gallicciolli wrote about this winter that happened when he was 25 year old: “as for 1709”.
206 The severe cold and its duration are confirmed by the instrumental readings, discussed
1775 ?
127 One hundred years after the event, the climatologist Francesco Zantedeschi wrote:
“December 10th, 1774 the Lagoon had ice that could hold people and large weights207.
According to the convention in use in climatology, this means winter 1775, the winter
being characterized by the January date. However, no confirmation has been found in the
local or other documents.
1766 VS
128 The contemporary Codex Gradenigo XXI (Anonymous, second half of the 18th Century)
reported that January and February were extremely cold, with snow and wind blowing
from North, and persistent ice, both inside and outside. The cold was similar to the level
reached in 1709. This caused lack of water, famine, illness and death in Venice. News
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arrived about the Rhone River supporting carriages, extreme cold in Ratisbon (Germany)
and Madrid, with killed people and animals. The temperature record by Beccari in
Bologna was interrupted on 18th January 1766 for the death of the observer, and reached
-8°C (Beccari, 1766). In Padua, the monthly average of the observations taken by Giuseppe
Toaldo was -4°C. However, no specific news was found about ice on the Lagoon. Possibly,
the cold happened in periods of lunar conjunction when the tidal exchanges are maxima
and bring in large amounts of mild marine water.
1776 VS
129 Eye-witnessing this event, Giuseppe Toaldo wrote that in January the Lagoon around
Venice and some canals were frozen over impeding access to the hinterland. The Republic
sent some workmen to break the ice sheet for the passage of some boats.208
1784 VS
130 Giuseppe Toaldo noted: “The past December 1784 was very harsh for the cold” 209. The
contemporary Giuseppe Gennari, living in Padua, in his diary noted: “The mercury in the
thermometer dropped by 8 degrees [°C] below zero. The Lagoon was frozen over and for
two days we had no mail from Venice”.210 Zantedeschi added: January 1784. The Lagoon
was frozen over impeding access to the hinterland and keeping Venice without contacts.
A number of boats were trapped in the suddenly formed ice”.211
1789 GW
131 Reliable instrumental readings were taken by the Patriarcale Observatory in the centre of
Venice that recorded -13 °C on January 12th. In Padua, Toaldo noted in his daily logs at the
Specola Observatory that the Lagoon was frozen and the air temperature readings
reached -15.4 °C in December 30th 1788 and -15.5 °C on January 1st, 1789.
132 Giuseppe Gennari in his diary the January 4th 1789 recorded that the Lagoon was frozen in
the shallow part of the marshes and that he got the announcement that the Po River too
was frozen.212 The event was carefully described with many colourful notations about the
daily problems and social implications in mid-19th century in the Anton Angelo Cavanis'
Diaries213. A few details, like the frozen wine, are similar to Virgil in Georgics, book 3, lines
360-366:Sudden ice crusts form on the running stream, and the water bears on its surface iron-
bound wheels – once welcoming ships, but now to broad wagons! Everywhere brass splits, clothes
freeze on the back, and they cleave with axes the liquid wine; whole lakes turn into a solid mass,
and the rough icicle hardens on the unkempt beard.” We will only quote and summarize a few
climatologic notes. From Cavanis' Diaries: "Because of the extreme cold which began in
the second half of the month with heavy snowfall, the Lagoon froze on December 28. On
January 30 people began to cross on foot the Lagoon from Venice to Mestre and vice
versa". This situation lasted for many days so that Venice was hit by famine. "All the
Lagoons and the internal canals were frozen over, except for the Giudecca canal which
was only partially frozen because there the tidal currents are stronger. Similarly the
canal to Fusina was filled by slabs of ice from other parts of the Lagoon, but people could
cross it on foot safely". Ice started to melt on January 10th, 1789. Zantedeschi214 reported:
“ice in December 1788 and January 1789 when the Lagoon was crossed on foot for
eighteen days, until January 14th. The thickness of the ice slab reached 8 inches [i.e. 23.2
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cm; 1 Venice inch = 2.898 cm]”. The winter was also commented by Levi, who contacted
several eyewitnesses and reports that the temperature dropped 18 degrees below zero. 215
Probably he intended -18° Réaumur scale because -18°R =-14.4°C, more similar to the
official readings.
1799 VS
133 “In December 1798 and January 1799, in addition [to the Venice Lagoon] the Adige and Po
Rivers too were frozen over and were crossed on foot by the [unrest and revolutionary]
1820 VS
134 On January 8th a violent Bora wind blew polar air and it was followed by snow from 9th to
11th and then, in the 13th. The temperature dropped to -6°C and the Lagoon started to
freeze. The 17th the temperature returned milder and with sunshine, melting the ice217.
The event, that falls within the definition of one week VS winter, was well known and was
quoted by leading authorities, such as François Arago and Easton.218
1823 VS
135 January was started very cold, with ice, hoarfrost and clear sky. The coldest day was on 4
th, when the thermometer reached -6 °R (-7.5°C) and the Lagoon was frozen. In the
following days, snow and cold that lasted until the 17th when the Sirocco wind brought
1864 VS
136 January. The Lagoon was frozen over and sustained the weight of people in the area
between the Fondamenta Nuove and San Michael Island. This event was engraved on a