Roman-Egypt's grain supply

Egypt was once the Roman Empire’s source of wheat. Disruption of this source of food had major impacts on the stability of the Empire. Rebellions, barbarian invasions, epidemics, and droughts played a role in this instability. Researchers are now investigating the impact of climate change on the wheat supply by examining wood samples from mummies buried during the Roman era:

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University of Geneva analyzed more than 300 wooden tags that had been affixed to Egyptian mummies during the Roman era in an effort to study the eastern Mediterranean's ancient climate. Much of the wheat consumed in the Roman Empire was grown in Egypt, so climate fluctuations in the region would have had a wide influence. The labels, inscribed by family members with the name of the deceased, the names of the person’s parents, and sometimes a short religious message, would have been sent with the body to the embalmer. For today’s scientists, the wooden tags also hold clues to the climate of the past in the form of the tree’s growth rings. Broad rings indicate rapid growth in a wet year, while narrow rings can be the result of drought.

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Thus far, wood from the Ptolemaic (332–30 BCE), especially the Roman (30 BCE–395 CE) period, has remained much less documented than that of the Ancient Egyptian (3150–332 BCE) period. However, rich collections of hitherto unexplored Greco-Roman wood objects are preserved in many museums worldwide. A study of these collections is therefore key for the construction of absolutely dated conifer chronologies, but is also considered to have a high potential to enhance our understanding of practices and customs during the Roman period in Egypt. Considered a pivotal time, the Roman period experienced large-scale transformations and external threats (i.e., military anarchy, civil wars, galloping inflation, famines, raids, and invasions; Alföldi 1938; Blois 2002); epidemics (Elliott 2016; Huebner 2021) and a succession of droughts (Manning 2013; Harper 2017).

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“Mummy labels are just a proxy tool that we are using to reconstruct the climate of Roman Egypt, the breadbasket of the Roman Empire, and understand how climate fluctuations influenced changes in society, government and the economy”. It is a perfect example of how questions raised by ancient history can be of pressing importance to the modern-day world.

Mummy labels of different quality from the BNU collection in Strasbourg were used to acquire dendrochronological measurements. Top left: Growth rings on mummy label HO87 cannot be measured easily due to tool marks and surface coating. Top right: Mummy label HO66 has a clean surface and perfectly readable rings. Bottom left: growth rings on label HO59 are only partly visible as a result of the cutting method applied and tool marks, the central part is illegible. Bottom right: Growth rings on the transverse plane of mummy label HO43 as seen on a X-ray tomography image with perfectly legible rings

https://www.archaeology.org/news

https://www.snf.ch/en/XlYUJjBFhCvE38RC/news/mummies-provide-the-key-to-reconstruct-the-climate-of-the-ancient-mediterranean
 

The scholarly article:

https://brill.com/view/journals/ijwc/aop/article-10.1163-27723194-bja10017/article-10.1163-27723194-bja10017.xml

Distribution of the 599 labels for which the location of finds is known, as well as the distribution by label type: Type I, Stela shape rectangular; Type II, Stela shape trapezoidal; Type III, Stela shape close to square; Type IV, Stela shape with handle; Type V, Tabula Ansata

Let's not get carried away. The Egyptian grain supplied the City of Rome, not the empire as a whole, and there were frequent shortages. Augustus banned 'useless mouths' from the city, Claudius was pelted with stale crusts, and I believe there was a shortage during Nero's reign too, just to name three events.

^^^ Good point.....The Italian penninsula has preciuous little land with good soil. Rustics could grow enough for themselves, but had little excess to ship to Rome for inhabitants who were not in a postion to grow their own, so importing grain from foreign sources was critical.

Those authors seem to forget that tree rings reflect mostly the availability of water, with temps being irregularly & innaccurately correlated with ring diameter....Also, crop yeid is influenced by water availability. In most regions, that means amount of precipitation, but for Egypt where irrigation using the endless supply of water from the Nile is to be considered, wet & dry yrs had little impact. Years of food scarcity had more to do with pestilence than weather.

On close examination of the data by those who have no political agenda to support, "climate' ( really just weather) is seen to vary complexly & cycllcly with  major periods of 11, 60, 500 and 1000 yrs.....If we can believe the proxy data over the last 2000 yrs, at no time have temps been more than +/- 2 SDs from the mean, ie- all falling in the "average" range).

OTOH, it's documented by Polybius & Livy that Hannibal and his entourage suffered miserably crossing The Alps ~200 yrs before Caesar's time. Caesar doesn't even mention snow or ice in his Commentaries, althoug he spends partcular attention to observations on natural history in those excursions....Lately, we see the Alpine glaciers receding, revealing fallen trees carbon dated to Caesar's time. They didn't sprout thru glaciers, but obviously grew on open soil....The story of Hansel & Gretl is based on the all too frequent problem faced by families starving during the Dark Ages when Europe was at the cold end of it's cycle and crop yields were down.

Things get hotter. Things get colder, but the average is maintained.

5 hours ago, guidoLaMoto said:

Those authors seem to forget that tree rings reflect mostly the availability of water, with temps being irregularly & innaccurately correlated with ring diameter.

Thank you for reading my post. You made some interesting and very credible points.

I would say, however, that the above description of the cause of the ring width is possibly a little too simplistic. I like the multifactorial explanation below better. It seems to me that ring width is a useful tool to assess not only precipitation, but it is also useful to analyze a large array of local climate conditions.
 

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The mean width of a ring in any one tree is a function of many variables, including the tree species, tree age, availability of stored food within the tree and of important nutrients in the soil, and a whole complex of climatic factors (sunshine, precipitation, temperature, wind speed, humidity, and their distribution through the year). The problem facing dendroclimatologists is to extract whatever climatic signal is available in the tree ring data and to distinguish this signal from the background noise.

https://www.sciencedirect.com/science/article/abs/pii/B9780123869135000132