Roman Warm Period : Timeline and Decline

Updated 2019 01 01: Format corrections for entries pertaining to years 558 and 559

The Roman Warm Period covered the interval from about 250 BC to about 400 AD.  It had helped to bring the Roman Empire to its apex, when the City of Rome had about one million residents.  The might, size and wealth of the Roman Empire declined when the Roman Warm Period came to an end.  The decline of the Roman Empire can be discerned in the trend of the size of the population of the City of Rome over time.
(The decline or shrinking of the population of the City of Rome happened within the context of decline and fall of the Roman Empire.  More on that context is addressed in What caused the decline and fall of the Roman Empire? , but weather events like those shown farther down in this blog posting played key roles.)

Roman Warm Period, Roman Empire and the population size of the City of Rome

Decline of Roman Empire reflected in the Population Trend of the City of Rome

There should be little doubt that the fate of the Roman Empire was strongly tied to the  Roman Warm Period that had helped to bring it to its apex and to the downturn in temperature trends that brought an end to the Roman Warm Period and continued long after.

Holocene Epoch: Subatlantic Chronozone

Holocene Epoch: Subatlantic Chronozone

The decline and fall of the Roman Empire initiated the European Dark Age (the Early Middle Ages, from about the 5th to the 10th century).  What the Barbarian Invasions –  motivated by Northern European tribes seeking warmer climes – began, the Islamic Conquest of the Middle East, Asia Minor, the Balkans and North Africa, finished with a vengeance. Beginning in 633 AD, a year after the death of Mohammed, the Islamic Conquest had expanded by 710 AD to include all of the regions of North Africa that bordered on the Mediterranean.  The Islamic Conquest was not finished.  In 711 AD it continued with the invasion and occupation of Spain.  That occupation came to an end in 1491 AD.  (More at The Islamic Invasion and Conquest of the Roman Empire — Crime of Opportunity)

Roman Warm Period and its Aftermath: Notable Weather Events

The weather events quoted here took place during and after the Roman Warm Period, until the time of the start of the Islamic Conquest of the World.  For records of subsequent weather events, refer to the Chronology that is the source of the quotes shown in the following.  The following quotes are only for instances of weather events whose descriptions contained the character strings: Rome, Danube, and Rhine, for the interval from 1 AD to 633 AD, the beginning of the Islamic Conquest of the World.

6 A.D. A famine struck Rome, Italy. 57, 72, 91
In the 43rd year of Augustus Caesar, a terrible famine struck Rome, Italy. Augustus sent away not only strangers but also most of his servants out of the city. [Because he could no longer feed them.] 72

15 A.D. In Rome, Italy, the Tiber River overflowed and did such serious damage that it was proposed in the Roman Senate to diminish its waters by diverting some of the chief tributaries.47, 92 Also refer to the section 14 A.D. – 15 A.D. for information on the famine in Ireland during that time frame.

52 A.D. A great famine struck Rome, Italy.72

70 A.D. Tacitus reports that an unprecedented drought took place in the year 70. There was no water in the north of Gaul [western Europe] and the Rhine River in western Germany was barely seaworthy [because of the low water level].79

79 A.D. – 88 A.D. Italy. Famine There was a terrible period of suffering from 79 to 88 A.D. when the Roman world seemed to be shaken to its physical foundations. A devastating drought and famine swept over the Italian peninsula. It is said that 10,000 citizens died in a single day at Rome during its height. Tacitus left a grim picture of the distress and suffering. Houses were filled with dead bodies and the streets with funerals.84

154 A.D. In Rome, Italy in 154, during the 16th year of the reign of the emperor Antoninus, the city suffered from the following calamities. First the Tiber River overflowed its banks. Then a fire destroyed a greater part of the city. Then a famine swept away a great number of its citizens.92

175 A.D. A famine struck Rome, Italy. 57, 72, 91

189 A.D. A famine struck Rome, Italy. 72

191 A.D. A famine struck Rome, Italy.72

192 A.D. A famine struck Ireland. Bad harvest caused general scarcity, mortality and immigration – “so the lands and houses, territories and tribes, were emptied.” 57, 91 A famine afflicted the city of Rome, Italy. 72

262 A.D. A famine at Rome, Italy attended by a plague.90

271 A.D. Of Rome in 484, or in the year 271 of the Christian era, the winter was so severe, that the snow covered the square in Rome, Italy to a height of several feet for 40 days.80

Winter of 298 / 299 A.D. Towards 299, the winter was very harsh in the north of Gaul [During the time of Ancient Rome, Gaul was a region of Western Europe encompassing present day France, Luxembourg and Belgium, most of Switzerland, the western part of Northern Italy, as well as the parts of the Netherlands and Germany on the left bank of the Rhine.]. 62 The winter of 299 A.D. was very severe in the north of France. 171

300 A.D. Start of the first phase of the Barbarian Invasions

The first phase of the Barbarian Invasions, from 300 AD – 500 AD, put Germanic peoples in control of most areas of what was then the Western Roman Empire. (More at Wikipedia,

352 A.D. In England, the Severn valley flooded; great loss.47, 92 [Other sources place this flood in the year 350. 40, 43] In 352, Severn carried off much people and cattle.72 On 5 August 352 A.D., it snowed on the Esquiline (seven hills of Rome, Italy), in the heart of the Roman summer.171 In 352 A.D. during the period between 28 July and 26 August, there was a drought in China. 153

357 A.D. The summer drought of 357 allowed individuals to ford and cross the Rhine River in Germany. 79

377 A.D. In February 377 in northern Gaul, the barbarians cross the Rhine River on the ice. 79

410 A.D. In Rome, Italy, there was a famine followed by a plague.57, 72, 91 Under the Emperor Honorius (who reigned from 395 to 414), so great was the scarcity and dearth of victuals in Rome, Italy, that in the open marketplace, this voice was heard – set a price on man’s flesh. St. Jerome alluding to this plague, says: the rage of the starved with hunger broke forth into abominable excess, so as people mutually devoured the members of each other. Nay, even the tender mother spared not the flesh of her sucking child, but received him again into her bowels whom she had brought forth a little before.72 In Rome, Italy, when Lucius Minutius was first made overseer of the grain, many commoners left so that they should not be tortured with a long famine, covered their faces and cast themselves headlong into the Tiber River.72

449 A.D. In 449, there was a great famine in Italy. 128

450 A.D. In Gaul in the year 450, the weather seasons were extraordinary.79 In Rome, there was a famine followed by a plague.72 In Italy, there was a severe famine – so severe that parents ate their children.57, 90, 91 During the severe famine of 450 in Italy, the Roman emperor decreed that parents who sold their children into slavery had the right to purchase them back with a 20% surcharge.86 A grievous famine afflicted Italy, so that many people sold their children to buy food. This was followed by a plague.72 During the reign of Turgina about 450 A.D. there was a great famine in Kashmir region of India. This famine was attributed to frost.179 During the period between 24 August 450 and 16 May 451, there was a severe drought in China. 153

Winter of 461 / 462 A.D. Danube River was frozen.1
– Theodomir (King Theodomir of the Ostragoths Amal) with his army crossed the ice on the frozen Danube River to avenge his brother’s death.
– The Var River in southeast France was frozen. 60, 62
– The winter in Swabia (currently a region of Bavaria, Germany) and Provence (a region of southeastern France) was very severe. 62
– In 462 A.D., the Var River in southeast France also froze completely.79
– The winter of 462 A.D. was very severe in Province, France. The Var River was frozen.171
– The Black Sea froze completely. The Rhône River in France was frozen across its width.61

480 A.D. The Tiber River in Rome, Italy froze over.33

500 A.D.  Start of the second phase of the Barbarian Invasions

The second phase of the Barbarian Invasions, from 500 AD – 700 AD, saw Slavic tribes settling in central and eastern Europe (notably in eastern Magna Germania), gradually making it predominantly Slavic. Additionally, Turkic tribes such as the Avars became involved in this phase. (More at Wikipedia,

More at “The Islamic Invasion and Conquest of the Roman Empire — Crime of Opportunity

Winter of 507 / 508 A.D. Danube River was frozen over and more or less all the rivers of Europe were frozen.1
– So severe a frost all over Britain that the rivers were frozen up for about two months.
2, 40, 41, 42, 43, 47, 93
– In the year 507, the frost [in Britain] was the severest for 2 months.72
– In 508 A.D., there was a frost in Britain. All the rivers in Britain were frozen for over 2 months.212
– It was very cold in Britain and the rivers were frozen for 2 months.28

558 A.D. – The River Thames in England was frozen for six weeks.29

559 A.D. – The Danube River was frozen this winter.62
– In the year 559, the Bulgarians crossed the frozen Danube River, spread over the region of Thrace, and were close to the suburbs of Constantinople.62
– The winter of 559 A.D. [in France] was very severe in the south.171

565 A.D. There was a plague in Rome, Italy, from the rains and floods of 564.72

590 A.D. In Italy, there were great floods from tempest; followed by a plague.47, 72, 92 In 590, there were long rains and a plague after.72 In 590 A.D., there was a famine from a tempest that raised a great flood.57, 72, 91 Rain fell in the months of September and October incessantly for many days and raised such floods in all rivers and lakes in Italy, as to overflow their banks and drown an infinite number of people and cattle. The rain was accompanied by tremendous tempest of thunder and lightning. The river Tiber swelled so high that all the fields, which were not hilly and mountainous, were overflowed. Many people believed it was a second great flood. In Rome, Italy, the Tiber swelled so high that in some places it reached to, and in other places overflowed the cities high walls. And the water rushed in with such fury that is spoiled and defaced the greatest part of the buildings that were near the river. When the floods ceased, the fields were so soft and covered with slime and mud, that they could not be tilled or sown, hence a general famine. The flood not only demolished many stately buildings and ancient monuments, but also got into the church granaries, and carried away many thousand measures of wheat. After the flood, the river brought down innumerable multitude of serpents, and among them a monstrous great one as big as a great beam. All these serpents were swimming down the river into the sea, where they choked, and their carcasses being cast on the shore. There they rotted and by the stench of the slime and mud and excessive moisture, and the air was so corrupted, that a most desolating plague ensued over all Italy, Spain and France. The plague raged and laid waste to many towns. In many 2/3 of the people died. It was most severe at Rome, followed by Liguria [in the coastal region of northwestern Italy] and the Venetian territories [in northeastern Italy], both by floods, famine and plague.72 [The source identified this flood in the year 588 or 589 A.D..] Powerful rains with violent thunder produced severe flooding in Western Europe. These heavy rains reigned in the fall of 590.79 591 A.D. Following the heavy rains, and disastrous floods of 590 AD, the year 591 produced a drought in Western Europe. 79 The summer of 591 A.D.was unusually hot [in France]. 171 The year 591 A.D. in Western Europe was divided as it were between an excessive droughts, which ruined all the meadows, and heavy rainfalls followed by floods, which destroyed much of the hay harvest.79 The excessive dryness of 591 A.D. in Western Europe consumed all the fields.79

592 A.D. There was a drought that lasted from 10 January to September, along with a plague of locust. This produced a famine. 57, 72, 91
There was a remarkably great drought from January to September, attended with a grievous famine and great swarms of locusts, which for two years ate up every green thing and caused a terrible famine in Italy. But they continued for 5 years in Capitaneo, then shifted to another province.72 [Capitaneo may have been end of the Italian peninsula near Bari in the southern Adriatic.]

Winter of 592 / 593 A.D. It was in southern Gaul [Western Europe] such a severe winter that no one living ever remembered a similar winter.62 The winter of 593 was “unprecedented” and extremely harsh in Provence, France. 171

Source: “A Chronological Listing of Early Weather Events,” 7th Edition, by James A. Marusek

Last but not least (and there are many more instances of weather events during the interval for European regions and specific locations), when the Roman Warm Period was definitely over,  came the Islamic Invasion and occupation of most of what was left of the Roman Empire:

In 633 AD The Islamic Invasions of the Middle East, Egypt, all of North Africa, as well as much of Europe, began after the death of Mohammed (632 AD).
More at “The Islamic Invasion and Conquest of the Roman Empire — Crime of Opportunity

References (for  the quotes above that were excerpted from “A Chronological Listing of Early Weather Events,” 7th Edition, by James A. Marusek)

1. Charles Peirce, A Meteorological Account of the Weather in Philadelphia from January 1, 1790 to January 1 1847, Lindsay & Blakiston, Philadelphia, 1847.

2. The Tablet of Memory; showing every Memorable Event in History, from the Earliest Period to the Year 1817. Thirteenth Edition, London, 1818.

28. Christopher Chatfield, Landmarks of World History: The Gallery of Natural Phenomena, 2010, URL: [cited 19 June 2010].

29. Where Thames Smooth Waters Glide: Frost Fairs, URL: [cited 20 June 2010].

33. List of Rivers and Harbors that Use to Freeze, 19 December 2009, JP Simon URL: [cited 23 June 2010]

40. Tablet of Memory, Shewing Every Memorable Event in History from the Earliest Period to the Year 1783, Fifth Edition, 1783, G. Robinson, London.

42. William Darby, Mnemonika or the Tablet of Memory, being a Register of Events from the Earliest Period to the Year 1829,
Edward J. Coale, Baltimore, 1829.

43. The New Tablet of Memory; or, Mirror of Chronology, History, Statistics, Arts, and Sciences, from the Earliest Period to the Year 1838, Fifteenth Edition, 1838, Longman et. al., London.

47. (Royal) Journal of the Statistical Society, Volume XLI – Year 1878, London, Edward Stanford, 1878.

57. Cornelius Walford, The Famines of the World: Past and Present, Edward Stanford, London, 1879

60. M. Benoist, Dictionnaire de Géographie Sacrée et Ecclésiastique (Volume 3), Paris, 1848.

61. Bulletin de la Société Departmentale D’Archéologie et de Statistique de la Drome, Au Secrétariat de la Société, Valence,

62. Franz Arago’s Sämmtliche Werke (Volume 8), Verlag von Otto Wigand, Leipzig, 1860.

72. Thomas Short, A General Chronological History of Air, Weather, Seasons, Meteors in Sultry Places and different Times, London, Volumes 1 & 2, 1749.

79. Joseph-Jean-Nicolas Fuster, Des Changements dans le Climat de la France, Histoire de ses Révolutions Météorologiques, Paris, 1845.

80. Filosofia della Statistica esposta da Melchiorre Gioja, Tomo Primo, Milano, 1826

84. Ralph A. Graves, Fearful Famines of the Past, The National Geographic Magazine, Volume XXXII, No. 1, July 1917

86. Cormac Ó Gráda, Famine: A Short History, Princeton University Press, Princeton, 2009.

90. Benjamin Vincent, Haydn’s Dictionary of Dates and Universal Information, G.P. Putnam’s Sons, New York, 1893.

91. Cornelius Walford, The Insurance Cyclopaedia, Volume III, London & New York, 1874.

92. Cornelius Walford, The Insurance Cyclopaedia, Volume IV, London, 1876.

93. Cornelius Walford, The Insurance Cyclopaedia, Volume V, London, 1878.

128. Chronology of Public Events and Remarkable Occurrences within the Last Fifty Years or from 1771 to 1821, London

153. Shan-yu Yao, Floods and Droughts in Chinese History, their Distribution and Correlation, 206 B.C – 1911 A.D., University of Pennsylvania, Thesis, 1941.

171., Evénements météorologiques de l’an zéro à l’an mil, URL: 1000.php [cited 7 June 2012].

179. Prithwis Chandra Ray, Indian Famines: Their Causes and Remedies, Calcutta, 1901.

212. E.J. Lowe, Natural Phenomena and Chronology of the Seasons, London, 1870.
Source: “A Chronological Listing of Early Weather Events,” 7th Edition, by James A. Marusek


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2 Responses to Roman Warm Period : Timeline and Decline

  1. Cause and consequence — What caused the decline and fall of the Roman Empire?

    Someone on Facebook, in relation to what is being presented in ‘Roman Warm Period : Timeline and Decline’, stated: “I suspect that the Roman empire was in decline mostly due to it’s internal political problems and the cooling was just the last straw. I also suspect the same drought, famine, plagues cycle will happen to modern societies when the cooling begins.” With that, he presented a modified version of the Alley temperature reconstruction. Central Greenland Temperature, 4,000BP to present. modified (apparently by Andy May) from Alley 2004


    With respect to the graph he presented, “Central Greenland Temperature, 4,000BP to Present (Modified from Alley, 2004)”, the author of those modifications is apparently Andy May. The latter presents and discusses the Alley temperature reconstruction and his own take on some of the peculiarities and discrepancies that he found to be of concern, in,

    Comparing the Kobashi and Alley Central Greenland Temperature Reconstructions“, June 25, 2016

    A very instructive debate of the issues identified by Andy May, is contained in the discussion thread that follows Andy May’s article. The key issue of Andy May’s deliberations and the debate following Andy May’s article is that the portion of the Greenland temperature reconstruction as shown in his original graph (shown above) exaggerates the magnitude of the Modern Climate Optimum (based on HADCRUT 4, calculated from daily temperature readings — shown in red — grafted onto the temperature reconstruction based on an analysis of the temperature proxy, the Greeland ice cores analyzed by Alley.

    As to the suspicion expressed by the FB commenter, without knowing what it would be, when I put together “Roman Warm Period : Timeline and Decline,” I had merely attempted to identify the places in the temperature timeline by Alley that corresponded to some of the records of individual, notable weather events that had affected the Roman Warm Period and its aftermath, focusing on the population trend of the City of Rome during that time.

    It had not been my intention to prove in that short write-up “that the Roman empire was in decline mostly due to it’s internal political problems” and that “the cooling was just the last straw.”

    As I pointed out in the related articles, I am not a historian, but I am aware that the historical records of that time are rather sketchy, imaginative, patchy and incomplete. They reported some incredible things, such as people in white gowns having conferences in the sky, and that babies who were still in their mothers’ wombs spoke to and had conversations with their mothers. Still, on the whole, some weather events of that time are on record, and it is generally accepted that they contain the truth with respect to having happened, having been severe and having had massively deadly consequences.

    It stands to reason that cooling caused adverse weather events, that those caused famines and large numbers of deaths (even wide-spread deadly plagues), that those in turn caused more economic problems, with the consequences of those then having been that the Roman Empire became afflicted by internal political problems. All of that was interspersed with the massive disturbances of large migrations, invasions, by Northern European tribes that sought to find refuge in more Southern, more comfortable regions that happened to be located in the Roman Empire. The motivating force for those migrations was without a doubt that the Goths and the Vandals from the Northern regions of Europe would most likely have felt the consequences of the cooling climate much more intensely than the people in the more Southern, warmer Roman Empire did.

    The suspicion that those consequences of the weather events caused by cooling were followed by “the cooling was just the last straw,” is a non sequitur, as there appears little doubt that the cooling of the climate was what had caused the climate’s deterioration..

    The weather events (I expanded the search to include not only Rome, but also Danube and Rhine) shown in the blog posting at the appended link illustrate that the Barbarian Invasions did not cause all of the famines but most likely took advantage of them (large portions of the population of the Roman Empire had died from starvation and disease, vacating their premises, so to speak, before the Barbarians came to occupy what the former tenants had left for them).

    Moreover, the cooling of the climate would without a doubt have helped the Barbarians more than it did the Romans. For instance, on February 377 A.D. in northern Gaul, the barbarians crossed the Rhine River on the ice, and in the winter of 461 / 462 A.D. the Danube froze over, allowing the Barbarians to cross the Danube without having to attempt to contest the heavily defended bridgeheads held by the Romans, while both of those rivers had been convenient natural obstacles that secured the northern boundary of the Roman Empire, but take a look at the weather events that — whether they triggered or aggravated internal political problems seems to be of minor importance — must have thrown the economy of the Roman Empire into considerable turmoil that presented obviously insurmountable difficulties to the contemporary government administration.

    Some of those weather events triggered famines and plagues of such proportions that in a virtual blink two-thirds of the residents of many towns perished. The survivors hunted travellers for food and ate them. Residents of towns ate members of their communities, mothers ate the children to whom they had given birth…, but have a look at some of the accounts from those times.

    We can be reasonably certain that the Barbarian Invasions did not cause the cooling of the climate that began shortly after 1 A.D., as the Barbarian Invasions did not begin until about 300 A.D., when the cooling had been going on for some time.

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