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Climate and Empire



The question about climate change and empire is sadly ever more relevant as climate change drastically transforms the world. So more research like this is valuable:

A new paper, just published Monday in the journal Nature Geoscience, proposes a link between a marked cooling event in the fifth and sixth centuries AD and a period of dramatic social change across Europe and Asia, including a pandemic plague outbreak, food shortages, political turmoil in China, migrations and even the rise of the Islamic empire. It’s impossible to say for sure whether the climatic shift was actually responsible for all the upheaval that went on during that time, the researchers say — but since the two periods coincided, the scientists are proposing that a connection is likely.

“There are a lot of things that occurred at the same time, and now it’s certainly very difficult to disentangle to what degree was it caused by climatic fluctuations,” said the study’s lead author, Ulf Büntgen, who heads a research group specializing in tree-ring science at the Swiss Federal Institute for Forest, Snow and Landscape Research. “But we just cannot exclude it anymore.”

In Europe, the colder climate is believed to have contributed to a decrease in agricultural output, which resulted in widespread food shortages. Around the same time, there was an outbreak of plague in the Byzantine Empire, which started around 541 AD and eventually achieved pandemic status as it spread throughout Europe, killing millions and contributing to the weakening of the Empire.

The researchers have hypothesized that the agricultural declines may have helped the plague bacteria spread from Asia into Europe via wildlife moving into the increasingly abandoned agricultural fields, although they acknowledge in the paper that much remains unknown about the plague’s origin and its link to climate during this time.

Additionally, historians believe there was a great deal of political turmoil in central Asia during this time period, with particular conflict within the regimes governing northern China. Meanwhile, it appears that Slavic populations were spreading across Europe. These events may have also been triggered by social instability caused by famine, crop shortages and disease outbreaks.

The authors have even suggested that there may be a link between climate and the eventual rise of the Islamic Empire. Changes in precipitation patterns, caused by the cooling, may have helped enable the growth of scrub vegetation on the Arabian peninsula, they note in the paper, adding that“larger camel herds may have facilitated transportation of the Arab armies and their supplies during the substantial conquests in the seventh century, during which the reconstructed fraction of human land use seems relatively high in the Arabian Peninsula.”

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  • Rob in CT

    There are many upheaval periods that you can kinda sorta link to climatic issues. The Bronze Age Collapse (~1200 BC) may be another one.

    But it’s tricky. The 6th century AD was also not so long (ok, a century, but I think the destruction of the Gothic Wars is key here too, and that’s on Justinian) after the disintegration of the Western Roman Empire, which you can possibly blame partially climate change and/or plague, but I can’t see how you can think about it without putting the political instability of the Empire from Commodus onwards front and center. The Romans fought civil war after civil war after civil war, over the course of ~250 years (235-285 was the worst stretch, but there was a ton of infighting afterwards too). What did that do to agricultural output? I can’t think it was good!

    I thought there was a school of thought that basically said that collapse of the (Western, anyway) Roman Empire may have helped *trigger* a cooling event (little ice age?), because of a massive population decline and all it entailed (reforestation mostly)?

    My understanding of the Rise of Islam is that the Eastern Roman Empire and the Sassanid Persians had *just* finished a highly destructive war in which they essentially exhausted each other. IIRC, the Romans basically lost 1 major battle and the rout was on. The Persians collapsed entirely. Was that exacerbated by climate change? Possibly.

    • Amanda in the South Bay

      Yes, the last Persian-Roman war was something not alluded to in the article, and that in most histories plays a very major role in the weakening of East Rome. I (as a rather amateur enthusiast for this time period) have never read of an explanation for the Roman-Persian war that deals with climate.

      Also not mentioned-the religious differences in the aftermath of the Council of Chalcedon (monotheletism, monoenergism) and how those differences exacerbated loyalty towards the Empire from the non Greek Egyptian population and in Syria.

      Ultimately I tend to think these kinds of articles tend to be rather too clever in finding clever explanations. Why did East Rome decline and Islam rise? Make the Battle of Yarmouk a decisive Roman victory, and right there *that* massively changes things, Justinian era climate change or not.

      • Ahuitzotl

        have never read of an explanation for the Roman-Persian war that deals with climate.

        Nor I, but I have read of links to the earlier pandemic & the subsequent weakening of manpower in the thematic forces .. so I guess if the pandemic is linked to climate, there we go. It’s a bit much of a longchain thing for my taste though.

  • medrawt

    So on a first skim of both the Post article and the journal article, I’m a bit perturbed, because the Post article refers to the “fifth and sixth century”, while the Late Antique* Little Ice Age actually appears to be, per the journal article, a sixth and seventh century event.

    Which is actually an interesting error, because in history as I have learned it, the disintegration of the Western Roman Empire and the migration of the various mostly-Germanic-speaking-peoples into the territories of the Empire, is typically presented as of-a-piece with the other upheavals that continue in Eurasia throughout the next couple of centuries. (And I’ve seen it hypothetically connected to climate change! re: viability of agriculture in the previously-held territories of the migrants, though I don’t recall whether there was direct evidence for that.) But if the LALIA is being specifically posited as a cause for all sorts of disruption, it doesn’t seem to have any bearing on the fifth-century collapse of the Western Empire.

    * Late Antique? I thought the preferred term for the period is Early Medieval, or is that restricted to Western Europe and/or now applied most specifically to something like the 8th-10th centuries?

    • Amanda in the South Bay

      I’ve noticed Late Antique for the period ranging from the mid5th century through to final initial Arab conquests of Spain.

      • medrawt

        With the understanding that that whole exercise of naming slightly arbitrary periods of time to satisfy a human compulsion for taxonomy is much less important than what one does with it, I’m not sure what’s gained by implicitly putting the Visigoths on the same side of a historical divide as the Romans, rather than on the same side as the Arabs (or, in the French context, not putting Clovis and Charlemagne into the same broad period).

        • Amanda in the South Bay

          My understanding is that Late Antiquity is usually distinguished by ending with the Arab invasions-which makes Clovis and Charlemagne of course on different sides of the divide. Its just that the conquest of Visigothic Spain was a bit further away in time from Yarmouk.

          • medrawt

            Right – what I mean is that if I want to understand first millennium AD French history, I don’t think I gain anything by putting a bigger conceptual split (between “Antiquity” and “Medieval”) between Clovis and Charlemagne than between Clovis and whomever was the local Roman governor in northern Gaul in the 3rd century. It makes more sense in Spain, but I think Spain is the only place in Western Europe where it makes more sense. Of course, the history of Eurasia shouldn’t be defined by what makes sense for understanding the history of its coastal fringes. Ultimately this is the problem (something I have to continually train myself out of, as a layman) of getting trapped by our perceptions of historical trajectory. Some dude farming along the Rhine in 600AD wouldn’t likely have thought he was living in a “transitional” period.

            • Hogan

              A professor of mine used to say, “As Adam said to Eve when they left the garden, ‘My dear, we live in a time of transition.'”

            • Lee Rudolph

              Of course, the history of Eurasia shouldn’t be defined by what makes sense for understanding the history of its coastal fringes.

              I’m sick of the incessant whining from Flyover Country.

    • njorl

      I noticed that too. I saw nothing in the paper about the 5th century.

      • rea

        500s = 5th Century is a classic careless mistake.

  • njorl

    I was just reading part of “Guns, Germs and Steel” about how the expanded fur trade of the 14th century increased the critical mass of people exposed to yersinia pestis to create an ongoing epidemic(furs are a viable vector for infected fleas). I wonder if the sudden cooling after 536 spurred the Byzantine empire to import more furs?

    For a brief window, a sufficiently large population would all be connected with a viable means of transmitting plague to each other without the epidemic burning itself out. Then, when it warmed, plague would again become a more episodic event.

    • Juicy_Joel

      Jared Diamond does a disservice to the real historical record- especially in “Collapse”.

      • Yes. Determinism has a lot of flaws and they are loud and clear in his books.

  • AMK

    Changes in precipitation patterns, caused by the cooling, may have helped enable the growth of scrub vegetation on the Arabian peninsula, they note in the paper, adding that larger camel herds may have facilitated transportation of the Arab armies and their supplies

    This is pretty weak. The Arabs used horses and mules at least as much as camels, and once they broke out of the Peninsula, they had access to the conquered territories’ livestock anyway. If climate changed helped their conquest, it was by weakening the Byzantine/Sassanid empires through disease and starvation. Imperial cities and garrison centers like Constantinople, Alexandria, Ctesiphon, etc. would have been far more susceptible than the smaller Arabian settlements.

  • Nick never Nick

    I think there was a book about this — it was interesting, but kind of devolved into a long explanation of how shit that happens before leads to shit that happens later You know, storytelling, that thing that historians hate.

    • You know, storytelling, that thing that historians hate.


      I love storytelling. I consider myself primarily a storyteller, albeit of particular sorts of political stories.

      • Nick never Nick

        I read some description of historical analysis once which discussed the ‘narratives’ as a problem for historians, in that they bypassed analysis and told stories — basically, the thing that Evolutionary Psychologists get criticized for. I got the idea that history had changed in the same way anthropology had, from descriptive ethnography to model-based analysis.

        In the book in question, for example, the entire premise was based on the fact that a volcano erupted in SE Asia at the beginning of a period in question, causing a series of collapses around the globe; and then these collapses were followed by the rise of states that are considered more ‘modern’, in that they themselves were destroyed by polities that we consider more current. It wasn’t wrong, per se — but taken too far, it’s pretty mechanistic, especially as you get further from the precipitating event.

  • Turkle

    If I remember correctly, climate change was the final nail in the coffin for the Comanche Empire… Has anyone else read Pekka Hamalainen’s book on the matter as well that can confirm my memory of this?

    • I don’t recall Hamalainen talking about this. Wasn’t this really about the destruction of the bison?

      • rea

        Climate change in 19th Century North America?

      • Andrew Isenberg wrote an interesting (and short) book about that. As I recall he argues it was the lure of hide trade profits that destabilized the plains tribes, particularly socially. So the buffalo herds were already stressed before the white hunters came and finished the job a few decades later. The plains tribes had become similar to agricultural monoculturalists, in that they only had 1 crop — buffalo. When that crop failed they had forgotten how to do anything else and had no time to adapt.

    • Nick never Nick

      There was another book, not scholarly — 1491 — that argued that the bison weren’t as numerous in the pre-Columbian era, and that their huge herds were a rapidly-developing product of environmental and population changes that took place following the colonization of North America.

  • j_doc

    I love Colin McEvedy’s historical atlases, and when discussing the western Roman decline he makes the observation that although there may have been fewer Romans, there sure seem to have been more Germans and Nordics. So if there’s a climate explanation, simply being cooler doesn’t entirely make sense.

    I also just finished Peter Heather’s book on the fall of the west (also recommended) and his thesis is basically a more sophisticated version of the “lots more Germans” bit. He argues that more numerous and better organized Germans were decisive; a resurgent eastern superpower and an active nomad cycle were necessary but not sufficient. Also hard to reconcile with “colder weather made farming harder in (western/southern but not northern/eastern) Europe”.

    • njorl

      I think the problem with the western empire was that the Romans depopulated it through intentional mismanagement, not climate. Gaul continuously declined in population from Caesar’s conquest to the Germanic invasions. The Germans invaded so easily because Rome had oppressed the population down to a tiny fraction of what it had been 500 years earlier.

      There was no need or reason to oppose the Germanic invaders. There was plenty of land for them to live on, and they weren’t nearly as bad as the Romans.

  • Tyro

    The idea of a volcano eruption in western hemisphere leading to climate upheavals in Europe and Asia has been well known for quite a while.

    Justinian’s over-extension and over-spending in trying to retake the western provinces fucked the empire good, but he couldn’t have predicted the plague, so it’s hard to blame him for that.

    As far as the spread of Islam, that’s really too far-fetch. The far more straightforward explanation is the traditional one: the Persian-Roman wars of the 7th century diverted trade and commerce through the Arabian peninsula, exposing the Arabs to new ideas and giving them a taste for more wealth. I’m curious about whether Arabia was facing a population explosion at the time, creating pressure for the tribes to move out and colonize the surrounding region, but I can’t find any data on the pre-Islamic population of the Arabian peninsula.

  • Peter T

    It’s not that determinism is wrong, it’s that there are so many determining factors. Climate is one factor. So are disease loads, and they are related. So is soil exhaustion, farming practices, deforestation (and they relate to disease and climate too), nomad and other enemy level of organisation, military technologies, policies, demographies…And we lack good data for almost all of these, and have to carefully extrapolate from various proxy indicators and very limited sources. All that said, books like the one by Peter Heather or the equally good one by Chris Brown (The Inheritance of Rome) show how much more we now know than we did say 40 years ago.

  • Peter T

    oops. Should have been Chris Wickham. Although Peter Brown on late antiquity is also very good.

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