For as long as I can remember I have enjoyed reading books about history. Not only are history books interesting in their own right, but they can also shed light on the climate in earlier times. Because most historians are solely concerned with their subject, and not with supporting one side or the other in “climate wars”, details of extreme weather events in the past are often narrated with apparent objectivity. All the more is this the case, if the history book in question was written half a century or more ago, before the climate crisis cult had even come into existence.
Currently I am reading “Hannibal – the Struggle for Power in the Mediterranean” by Sir Gavin Rylands de Beer. His foremost claim to fame is as an evolutionary embryologist, but he developed an interest in the Alps specifically and in history generally, which interests synthesised in his fascination with Hannibal and his journey across the Alps with elephants. He was the first (by detailed analysis of the historical sources – primarily Polybius and Livy – together with a study of how the landscape fitted their narrative) to propose the Col de la Traversette as the probable route taken by Hannibal. His theory received support a decade ago when a churned-up mass of sediment in a 1m-thick mire at Col de Traversette was discovered, that could be directly dated to the time of Hannibal’s invasion. Perhaps, then, Sir Gavin’s observations regarding history should be taken seriously.
We’re well used to scaremongering articles in the Guardian (“It has not been as hot as this for at least 125,000 years, prior to the last ice age, and most likely longer, potentially going back at least 1m years”), but what if they’re simply not true? Which brings me back to Sir Gavin’s book. It was first published in 1969, and I am reading a 1974 version, published a couple of years after Sir Gavin’s death. Back then, the main climate scaremongering was with regard to a possible return to an ice age rather than “global boiling”, but in any event discussion of the climate then lacked today’s hysteria and constant drumbeat of propaganda. And so Sir Gavin could calmly note that temperatures during Hannibal’s march could not be lower than they are today and may have been higher (or least that was the case in the late 1960s, when he wrote those words). He relied on four “independent methods” to assess the climate in Hannibal’s day.
The study of glaciers
He noted that the advance down valleys of glaciers depends on temperatures and on precipitation levels. We can see the limit of former glacial extension as shown by their terminal moraines. From the 16th to the 19th centuries CE (as we now say) he says that glaciers advanced much further than at any other time since the end of the last ice age. Thus the “present” condition of Alpine glaciers is not a diminished relic of their extension in the last ice age but rather of their extension during their recent (“Little Ice Age”) maximum.
He observed that as glaciers retreat, they are constantly leaving uncovered tree trunks from forests which were overrun during their more recent advance. Some such tree trunks have been found at an altitude of more than 2,250m. Classical authors also offer clues regarding the earlier climate – Strabo quoted Polybius as saying that in the Noric Alps there were gold mines that were worked profitably. This is today the region of the High Tauern in Austria. The Goldberg mines there were worked extensively in the Middle Ages, but in the 17th century CE the adits to some of the mines were covered as the ice once more advanced.
His conclusion: “It follows, therefore, from the evidence of glaciology that the temperature in 218BC[E] was at any rate not lower than it is at present.”
Studying the Height of the Tree Line
Here he is referring to places where the absence of trees is not attributable to the advance of glaciers or to the activities of humankind, such as pasturing of animals or felling trees for fuel use. He states that in northern Italy the tree line is at least 300m lower than it was. He was, of course, writing more than half a century ago, but I would be astonished if the tree line has risen there by as much as 300m in the intervening years. He references Virgil talking of pine-clad Monte Viso, and notes that it bears no pine forests today, and that Hannibal’s route passed close by.
Conclusion: “The inference is that the climate was then warmer”.
Pollen analysis
“These studies indicate that there were temperature maxima in 550BC[E] and in 1200 [CE], and between these periods a temperature similar to that in the present day.” From which I extrapolate that he concluded that it was warmer at the bookend dates he refer to than it was when he was writing.
Study of cores taken from the ocean bed
Here he refers to the quantity of calcium carbonate deposited being dependent on the temperature at the ocean surface at the time of deposition. The time of deposition is ascertained from the level in the core of the specimen being studied. He says that at the level corresponding to 550BC[E] the annual rate of calcium carbonate deposit was 1mm per square cm, whereas when he was writing it was 0.9mm. The values for 218BC[E] were intermediate between those of 550BCE and 1969[CE].
Conclusion: “the world temperature in 550BC[E] was 1 or 2 degrees higher than at present”. Sadly he didn’t say whther he was referring to degrees Celsius, but even if (as seems distinctly possible, given when he was writing) he was referring to degrees Fahrenheit, the point remains – it was warmer in 550BCE than half a century ago.
What to make of it all? Well, we must apply caveats. First, it might well be argued that science has moved on and the findings would now be different, given modern scientific methods (although it’s hard to argue away hard evidence such as the altitude of tree lines and retreating glaciers exposing previous forests that had been submerged when the glaciers advanced). Secondly, we will be told that if Sir Gavin was working in degrees Fahrenheit, then we have seen temperatures rise by at least his 1 or 2 degrees since 1850, and much of that warming has occurred since 1970. Nevertheless, even allowing for such caveats, there is a strong case for arguing that 2,250 or so years ago, the temperature was at least as high as it is now. We don’t hear talk of climate tipping points then, nor are we given to understand that the world was then facing a climate crisis.
We can learn a lot from history. Perhaps the main thing we should learn is that today’s temperatures are not unprecedented, there is no climate crisis, and we really should focus instead on the other issues jeapardising humankind and environmental well-being. There is, after all, no shortage of candidates.
Climate Scepticism 
The tale is usually that the Romans were surprised by the crossing of the Alps. There seems to be a tension here: the icier the Alps, the greater the surprise, but the clearer the passes, the more they should have expected it.
The Roman Warm Period seems well attested. The question is, what caused the earlier warming, and how much warmer is it today, thanks to the demon molecule?
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From what I can gather, the difficulty the Romans had was that they faced the combined problem of having despatched legions to what is now Spain (where they were in conflict with Carthage) at the same time as fighting an insurrection by the Gauls in what is now northern Italy (then Cisalpine Gaul).
The Alpine passes were regularly traversed – which might suggest that it was warmer then. The army on its way to Spain passed close to Hannibal’s army going the other way, while in the vicinity of the Rhone.
The Romans knew what Hannibal was up to. I think the only extent to which he really surprised them was his taking of elephants over the Alps.
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I thought I read recently (last couple of years?) that elephants do not like climbing hills and will take circuitous routes to avoid such climbs. So how did Hannibal encourage his elephants to tackle the non-trivial climb up and over the Col de la Traversette?
According to Wikipedia, “The Col de la Traversette is a bridle pass with an altitude of 2,947 metres in the Cottian Alps. Located between Crissolo and Abriès, it lies on the border between Italy and France and separates the Monviso from the Monte Granero. The Blue Trail of the Via Alpina and the Giro di Viso cross the pass.” https://en.wikipedia.org/wiki/Col_de_la_Traversette
2,947m is about 9,650ft in old money, or well over twice as high as Ben Nevis. That is a serious climb in anybody’s book given the changeability of weather in the mountains.
And as an engineer I am intrigued as to the energy requirements of an army of elephant alpinists; it is not something I studied at university. It will certainly amount to a lot of food; where did that come from?
Regards, John C.
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John C,
De Beer’s narrative suggests that Hannibal’s undertaking was a monumental one, with a considerable amount of forage being taken along. They fell greedily on some Roman stores when they reached lower ground. Also, a significant number of elephants were lost en route. He hadn’t been in Italy very long before he had only one elephant left.
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Bang on cue:
“Scrap Net Zero: Dramatic New Ice Core Evidence Shows Current Century Warming Common Throughout the Last 400,000 Years”
https://dailysceptic.org/2026/03/16/scrap-net-zero-dramatic-new-ice-core-evidence-shows-current-century-warming-common-throughout-the-last-400000-years/
Lies, disinformation and fictional accounting are the order of the day as a desperate hard-Left UK government, aided by its pet Climate Change Committee, tries to keep its impossible Net Zero controlling agenda intact. The bedrock unproven science claims surround the suggestion that recent limited global warming presents an existential threat to the planet. Statistics are routinely tortured to produce claims of up to 1.7°C warming from the pre-industrial age, notable as reported in a recent silly ‘Trump’s brave new world’ article by Ambrose Evans-Pritchard in the Telegraph. In fact, temperatures have only risen by around 1.1°C over the last 100 years. Moving away from the tortured stats measured over a few cherry-picked months, it has recently been discovered from ice core records that rises of 1.1°C in the current interglacial, which started about 20,000 years ago, occurred in about one in six centuries.
Moreover, similar, although less frequent, temperature rises appear in earlier periods going back 150,000 years. The frequency here was around one in six to one in 20 centuries. Of further interest was the discovery that these routine rises became rarer before this date. None of these findings suggest that current warming is either unusual or solely caused by humans burning hydrocarbons. Needless to say, the findings will be ignored – as is most other inconvenient palaeo evidence – by climate headbangers and political activists prepared to fib about the climate and waste trillions of pounds on their command-and-control Net Zero fantasy....
…Written by the Emeritus Professor of Computer Science at Kingston University Les Hatton, the paper analyses publicly-available temperature information going back around 420,000 years from the Epica-Vostok Antarctica ice core dataset. It accepts that the data do not provide a global figure, which it is noted is a statistical amalgam with many assumptions and numerous proxies. The more cynical might note here that current global temperature datasets contain a great deal of ‘junk’ unnatural heat measurements, and are subject to considerable suspicious retrospective adjustments. The author notes that the Vostok ice core is a ”pure” record since it is based on a single location in a consistent manner over a long period. Again, sceptics might welcome the lack of measurements next to airport runways, solar farms and glass-clad high-rise buildings.
Professor Hatton has some interesting general comments about temperature, noting that interglacial peaks starting 400,000 years ago appear to be getting hotter. The interglacials are followed by ice ages and these seem to be getting colder. Carbon dioxide levels do not seem to play a large part in all this natural variation as the graph below going back 200,000 years clearly shows. In some periods, the red temperature line moves in a different direction to the blue CO2 marker.…
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Fascinating read as usual Mark. Some sources put the Roman Warm Period as 0-500AD, others claim it started earlier in 250BC to 400AD, which puts Hannibal’s crossing just in the warm window, but it seems likely that the peak warmth occurred probably around 100AD, at the pinnacle of Roman civilisation, long after Hannibal. In fact, Hannibal’s crossing occurs during the Hellenistic period, which according to some was a time of relatively cool temperatures between the Minoan (3300 years ago) and Roman Warm Periods. But it’s debatable when the Roman Warm Period actually started.
I too am fascinated by our climates past and how they relate to historical events. For example, I’m currently researching the period during which the Ellesmere Canal was built, linking Mersey to the Severn navigation. The winter of 1794-95 was exceptionally severe and indeed January 1795 is the coldest month ever in the long running Central England temperature series. There came a very sudden thaw in February which resulted in a deluge of snow melt which flooded vast areas of the country and swept away hundreds of masonry and wooden bridges – but one iron bridge survived, and on this basis Thomas Telford is credited with the innovation of using cast iron to build road and rail bridges across the country and he is also credited with the stupendous 126 feet high cast iron atop masonry aqueduct at Pontcysyllte, part of the Ellesmere navigation spanning the River Dee. But it was actually the engineer William Jessop who was in charge of building the Ellesmere Canal and who oversaw the construction of the iron aqueduct at Pontcysyllte, however history credits Telford, who it seems was very happy to accept the plaudits, but was actually working under Jessop at the time.
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Thanks Jaime,
A fascinating and happy digression. I have seen the remarkable Pontcysllte aqueduct and agree with your description of it as stupendous. Regarding the winter of 1794-5, try this possibly equally damaging event from almost a century later:
The Solway Viaduct Disaster of 1881:
The winter of 1880/81 was extremely cold, with snow and freezing weather. During the neap tides of January 1881, water froze on the saltmarshes and shores of the Upper Solway, and along the estuaries of the Esk and Eden. When the higher Spring tides arrived at the end of the month, the sheets of ice were lifted and carried down the Firth.
‘On Saturday night and early on Sunday morning, when the principal part of the damage was done, four men were on the bridge keeping watch … They could not see the ice through the darkness, but they heard it rattling and bumping against the pillars, and, hearing several times amidst the general noise, while the ebb tide was running between two and six o’clock, a sound which one of them compared to the report of a gun, they at once came to the conclusion that some of the pillars had been broken…’ (Carlisle Journal, Tuesday February 1st 1881)
The ice floes were as much as 6 feet thick, of all sizes; some of them ‘suggested comparisons with fields that were one or two acres in extent’; some were as much as one hundred feet long. For the next few days, icefloes were carried to and fro by the tides, crashing against the viaduct’s supports.
On the Tuesday, a large section of the viaduct fell; ‘the sound was tremendous, and the steel coming in violent contact with other portions of the ironwork threw off so much fire that the thick darkness was illuminated with a transient gleam of light.’ (Carlisle Journal, February 4th 1881)…
A warming planet might be causing some problems in some parts of the world, but it’s almost certainly reducing problems in other areas – such as here in Cumbria!
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Mark, I’ve wanted to visit Bowness twice to view the remains of the viaduct, but on both occasions they closed the road!
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Third time lucky, then. 😊🤞
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Jaime, chapter 4 in “Thomas Telford” by L.T.C. Rolt (Longmans, 1959, pages 34 – 58) is entitled ‘Stream in the sky – the Ellesmere canal’. However, I fear that, from your perspective, it deals primarily with the engineering and personalities involved rather than with the weather aspects which are alluded to only obliquely:-
Page 46. “There is evidence in a letter from Telford to Matthew Davidson that James Varley was working at Pont Cysyllte at the beginning of 1995 if not before, but if this was so he can have done no more than clear the site. For it is evident, and scarecely surprising, that the Managing Committee were suffering from icy cold feet as the implications of Telford’s proposal sank deeper into their minds. The idea of boats floating across the Vale of Llangollen at a height of 120 feet would strike them as so fantastic that they must have wondered uneasily whether their engineer was a genius or a lunatic.”
Page 52. “By the end of 1793 the speculative whirlwind of the brief ‘canal mania’ had blown itself out. It was succeeded first by an ominous calm and then by the icy grip of a financial slump which froze many a half-completed canal work. In such an economic climate it is not surprising that Telford’s great aqueduct took ten years to build. Another result of financial stringency which really is remarkable was that in the passage of this decade the Ellesmere Canal main line abandoned both its original objective and took a totally different course.”
IIRC this was also roughly the time when volcanoes in Iceland erupted thereby darkeneing the skies of Western Europe leading to poor harvests which, in turn, helped to foment the French Revolution.
Regards, John C.
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Mark, here’s some research on Alpine glaciers pertaining to this topic.
It does look like the tree line was higher with the Roman warm period beginning, making Hannibal’s crossing possible and surprising.
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Ron, thanks for that.
History is so important, especially in the context of claims that current “extremes” are “unprecedented”. Of course, proxies can be useful, though there’s always the worry that they may have been misunderstood, misapplied, or even used nefariously (on both sides of the debate). Historical texts can be enlightening, but we always have to run them through a filter. Bearing in mind that historical works referring to battles often claim hugely improbable numbers of participants and casualties, we must be wary of similar extreme and inaccurate claims being made for the weather by historical chroniclers.
What do we make of this, for instance?
https://en.wikipedia.org/wiki/The_year-round_heat_and_drought_of_1540_in_Europe
Which is why an event such as Hannibal crossing the Alps with a huge army and with elephants is so valuable for efforts to assess what the climate may then have been like. Remember, too, that his crossing was in late October and early November. Not the depths of winter, but not high summer either, so one might assume that seasonal temperatures would be fairly low, and that snow would be reaching lower altitudes. It’s not conclusive, of course, but to me it’s strongly suggestive of it being warmer then than now, and certainly no colder.
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Mark, AI suggests that Hannibal started with 37 African war elephants; were there any other elephants (e.g. beasts of burden to carry the forage) in his alpine army? Getting such a large army of elephants over the Alps is such an incredible feat for the time that I am not surprised only one survived the ordeal.
If time permits I might attempt some crude calculations to see how much forage per elephant is needed for such an adventure.
Wikipedia (https://en.wikipedia.org/wiki/Hannibal%27s_crossing_of_the_Alps) suggests the crossing was attempted in May/July – late September 218 BC whereas you suggest (in your comment just above to Ron) that the crossing was in late October and early November. I do not know how that difference will influence my rough calculation.
Anyway, I just wanted to say that IMHO getting just one elephant over the Alps is a magnificent feat for the period; getting a herd over even today would be a sight that even social media might take more than a passing interest in. Regards, John C.
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John C,
Hannibal’s journey may have commenced, south of the Ebro in what is now Spain, in the summer, but de Beer was explicitly clear that the 15 days he spent crossing the Alps was in late October/early November (he goes into quite a bit of detail about this as part of his attempts to identify the precise route, as he assesses likely water levels in different rivers in late October). Also he references Polybius talking of being at the time of “the setting of the Pleiads“, and most people seem to accept that this occurs in late October/early November.
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Mark,
It’s rather surprising that the crossing was possible so late in the year. These days there is often light snow in September and heavy snowfalls can arrive in November at lower altitudes – down around 1500m. The ski-ing season typically opens at the start of December. That suggests that it must have been considerably warmer back then. Or…..
Is it possible that the dating is inaccurate? A quick look at Wiki advises that the Roman calendar was quite erratic until the introduction of the Julian system approx 170 years after the crossing, saying:
“Intercalation: Introduced an intercalary month called Mercedonius to align the calendar with the solar year. This month was added every two years.”
“Inaccuracies: The calendar often fell out of sync with the seasons due to irregular intercalation practices.”
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Searching a bit further, I found this description of the Col de la Traversette:
“The topography features steep ascents from both the French and Italian sides, characterized by rocky outcrops, extensive scree slopes, and remnants of past glaciation that contribute to its challenging profile.[14] Slopes often exceed 35–45 degrees in gradient, with loose debris and occasional avalanche-prone areas adding to the terrain’s severity above the treeline.[14] ……
…..Weather patterns at the pass are influenced by its high elevation and Alpine location, featuring frequent fog, prolonged snow cover from October through June, and strong exposure to prevailing westerly winds that bring moist Atlantic air.[17][18] These conditions often result in rapid weather shifts, with winter snow accumulation exceeding several meters and summer thaws limited by persistent cold snaps.”
I’m struggling to accept that elephants could cope with such terrain, especially in the probable harsh conditions in November.
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MikeH,
Nothing is certain, but there does seem to be increasing acceptance that the Col de la Traversette was the route taken by Hannibal:
https://www.qub.ac.uk/sites/Hannibal/Journals/
It’s worth noting that he fought two battles against hostile local tribes en route, and local guides enlisted along the way may have misled him. De Beer speculated that this might have resulted in him not actually taking the route he intended. If so, it may go some way to explaining why he lost so many elephants before arriving in the Po valley.
I’m being lazy and taking AI’s summary, but it repeates what de Beer says the evidence supports, regaring the nature of the elephants used, in any event:
Hannibal’s war elephants, specifically those used to cross the Alps, were likely smaller North African forest elephants (Loxodonta africana pharaoensis), standing roughly 2.5 meters (about 8 feet) tall at the shoulder. These were smaller than modern African bush elephants and Indian elephants, enabling them to be more easily handled, though this species is now extinct.
That might also explain how he managed to get some across difficult terrain.
Of course, the final explanation might be that the climate was milder then….which is why I wrote the article.
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It would seem that Hannibal’s elephant army was comprised predominantly of a now extinct African sub-species, the North African elephant (Loxodonta africana pharaohensis), which was smaller in stature than either the African or Asian elephant. As regards to its former natural range, I quote:
“Fossil evidence and historical accounts indicate that this extinct subspecies inhabited areas north of the Sahara Desert, including the Atlas Mountains in modern-day Morocco and Algeria. Its range extended across the Maghreb, encompassing coastal plains and forested fringes, with populations documented in regions like the Tighennif area in Algeria. The species was adapted to semi-arid savannas, woodlands, and Mediterranean climates, making the Atlas Mountains a suitable habitat. It is also referred to as the Atlas elephant, a name derived from this geographic association.”
So, I’m thinking that as the N African elephant was smaller in stature than either Asian or African savannah elephants, and as it was presumably adapted to foraging in the Atlas mountains, they would have been a more viable option for crossing the Alps than either of the two currently extant species of elephant. It’s just sad that none of them made it and that the sole survivor may indeed have been a now extinct subspecies of the Asian elephant.
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While researching elephant diets and metabolic rates I received this info. AI response to ‘hannibal crossing alps with elephants’ = “The Force: Along with 37 elephants—likely North African forest elephants—Hannibal brought roughly 30,000–70,000 soldiers and 15,000 horses across the mountains, say Facts and Details and Queen’s University Belfast.” [cf. Modern population data: 30k = Camberley or Whitstable, 70k = Stafford]
This is an enormous army which, I imagine, could have easily carried the forage for the initial army group of 37 elephants. I therefore redirected my thoughts from my inital concern (elephant forage) to how long it would take such a group to pass over the narrow Col de la Traversette route.
I assumed the average army size, namely 50,000 men plus 15,000 horses. I further assumed one column of horses could walk beside one column of men at the average of two men per horse length and 6m from horse nose to horse nose. This makes the cavalry part of the army of 30,000men have a length of 15,000 x 6m or 90km.
The remaining 20,000 infantry men in 2 parallel columns of 10,000 each with men spaced just 1m apart would be 10km long. Hence the whole army would be 100km long.
I then assumed a marching day of 8 hours total and an average marching speed of 2km/hr over rough, rising terrain for men in heavy kit and suffering from poor diets. So over the period of a 24 hour day the army advances, at best, at a rate of 1km/day.
It would therefore take the whole army about 100 days to pass over the Col de la Traversette. But the avant garde did it in just 15, which is very impressive blitzkrieg for the epoch. However, it does make my ask myself a couple of questions:-
Did Hannibal split his army into two or more sections to achieve his astonishing coup de guerre? Or are the figures for the size of his army exaggerated? Regards, John C.
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