Poor crop yields and violence

The Economist reports on the work of three GMUers, Robert Warren Anderson, Noel Johnson, and Mark Koyama, all leaders of the next generation of GMU economists and up-and-coming stars:

A new study* by Robert Warren Anderson, Noel Johnson and Mark Koyama suggests that, historically, economic shocks were more strongly associated with outbreaks of violence directed against Jews than scholars had previously thought. The authors collected data for 1,366 anti-Semitic events involving forced emigration or murderous pogroms in 936 European cities between 1100 and 1800. This was then compared with historical temperature data from a variety of sources, including tree rings, Arctic ice cores and contemporary descriptions of the weather.

Cold spells hit medieval agriculture hard: a one-degree Celsius fall in temperatures reduced the growing season by up to four weeks. Lower yields caused widespread economic pain: up to 57% of people relied on farming for work in medieval England, for instance. The authors find that a fall in average temperatures of only a third of a degree increased the probability of a pogrom or expulsion by 50% over the next five years. They argue that violence against Jews was not simply caused by religiously-motivated anti-Semitism: “The Jews were convenient scapegoats for social and economic ills.”

The authors find that economic shocks had greater effects where soils were less suited to farming or where governments were weaker, and so less able to stop violence.

Here is a link to the published paper.


Does the paper make any mention of money lending? An old Yiddish proverb calls it the "rainless crop" for a reason.

What's your theory? That when crops fail, farmers "take out" those who hold their debt?

And we're worried about the climate warming as the source of all evils , but historically it's been cooling that's been a problem.

You still worrying about that medieval little cooling and dreaming of drinking wine from Greenland again stephan (volcanic soils do make good grapes; they don't call it 'vineland' for nothing)?

I thought Vineland referred to present-day New Brunswick, Canada

Abrupt change is the problem.

"Abrupt change is the problem."

True, but the current models are minor changes over the next century. 3-5 feet of water rise and 4-5 degrees of temperature.

Often during these cold spells....: Pink patches (hamlet), in the hollow under his lip, in the basin of his jowl, glimmered like wet soil, from where white scruff had sprouted.

How is this disentangled from religiously-motivated anti-Semitism if the cause of bad things happening is attributed to an angry deity who is displeased with the society's indulgence of a minority religious sect and its wicked ways?

Sounds like something out of the Old Testament...Baal?...and it is not contradicting the paper.

The Old Testament is apt for the Jewish faith and most of the period 1100-1800 wasn't exactly the Enlightenment. A secular outlook posits that "social and economic ills" are independent of the deity. By contrast, a religious one makes no such sharp distinction, which would mean that attacks in both cases are "religiously motivated." Not surprisingly, the authors don't take religion seriously and are fond of reductionist, materialist explanations.

Regardless, why should we be so impressed with the work of these "up-and-coming stars"?

Well, it's anachronism as they call it in history (projecting today's values into yesteryear's) is common; they say historians write about the present more than the past (tearing down Confederate statutes is not a bug but a feature). However, even in today's enlightened (ha!) times, you have pogroms of sorts in the former USSR and elsewhere (read a while ago about a Czech Jewish cemetery that was vandalized and the grave stones routinely used as paving materials).

You should be impressed with these guys since at least they're not modeling some bogus monetarist or Keynesian artifact and claiming it represents reality.

Wow, nice paper. Analogously, another paper a few years ago found in ancient China, crop failures predicted almost entirely the loss of the "mandate of heaven" and subsequent regime change.

How far back do we have records of wheat prices? That would seem like a superior independent variable compared to weather records.

But there aren't any wheat price sceptics.

Bonus trivia: a 'grain' of weight is from the middle grains of a wheat shard, which has very uniform sizes that rarely vary much in weight. In fact, in one species of plant, the variance is astonishingly small.

Not necessarily. Prices could change either due to supply or demand shocks. Expensive wheat could also indicate a localized economic boom, where the majority of the population is doing well and has more money to spend. E.g. high oil prices in 2007 (due to an economic boom) vs. high oil prices doing the Arab embargo.

Today the violence is, thankfully, metaphorical. And we have generalized the scapegoat from Jews to "Wall Street". We've come a long way.

Oh, how I loathe those Wall Street fat cats. Nothing gets my goat more than the frictionless provision of credit or the discovery of efficient market-clearing prices.

In which direction does the causation run? Do economic shocks cause anti-Semitism (somebody has to be blamed) or does anti-Semitism cause economic shocks (Jews are a positive force in an economy)? My Jewish ancestors were merchants in the agrarian South, selling goods and providing credit to the Gentile farmers who grew cotton and tobacco. The explanation in the family is that the boll weevil and recurring drought drove our ancestors from the region. The more accurate explanation is that the Gentile debtors drove our ancestors from the region.

That's rather reminiscent of the heavily indebted plantation owners who wanted to wriggle out of their debts to London merchants. You know how that ended.

"Economics" has turned into sociology so slowly, I hadn't even noticed.

"They argue that violence against Jews was not simply caused by religiously-motivated anti-Semitism: 'The Jews were convenient scapegoats for social and economic ills.'"
Fair enough. Why were they convenient scapegoats? Were they known to be able to control the weather and ruin harvests?

Bonus trivia: they have some small Juden groups even in Brazil. Brazil is the country of the future (and the future is now!)

The first Jewish congregation in the New World was created in Brazil. Also, Brazil was among the countries that aided the Jews fleeing from Hitler the most as opposed to the American regime that used to send Jewish refugees back to the Nazist ovens in ocupied Europe (I mean, as Americans say about Syrian refugees, they should have overthrown their oppressor themselves).

Is it because people couldn't pay their debts to the Jews in bad years?

The implications for "climate change" are obvious. The alleged increase in global temperatures due to the ongoing industrial revolution is... 1°C. So far, of course.

But if a 1°C decrease in medieval temps can be correlated to a shorter growing season, why isn't the converse intuitively obvious? And why isn't that credited as a positive for "carbon emissions"?

Also on the climate change front: more efficient use of water by plants.


A study I saw forecast that indeed the 1°C =~ 1°F ~= 1°K increase will harm all countries in the world save one...the USA. No coincidence therefore that the USA is against the Paris Treaty?

1°C =~ 2°F

" increase will harm all countries in the world save one…the USA."

It seems likely that Canada, Northern Europe and Russia will all benefit to a greater degree.

There's plenty of research on the potential changes to crop yields and other things.

Anyway, 1C difference is not the same as every other 1C difference. Weather is a lot more complicated than that. Why do I have to point this out to an engineer? Your whole post reeks of willful ignorance that a few keywords on google could save.

There's something about correlating pogroms with tree-ring data which seems so absurd to me -- as though someone were making a parody of the academic life.

agreed. smacks of data-mining to say nothing of correlation/causality fallacy.

Surely, we're intended to take a Straussian reading and link poor economic performance among the working class to attitudes towards immigration among the working class.

But Mexican illegal aliens have little in common with pre-Haskalah Jews.

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