In the 14th century, four centuries of mild weather came to an abrupt halt in Europe. Famine and frigid temperatures ensued, and roughly 10 percent of the population died.
Long before the bitter cold winters and drenching rains of the early 14th century announced the end of the Medieval Warm Period (MWP), Europe had expanded dangerously close to the limits of its resources. Four centuries of unusually mild temperatures (the highest in 8,000 years), prompted the continent’s farmers to plant crops on vast quantities of land previously unsuitable for agriculture; the increased food supply in turn fueled a population explosion that tripled the number of people in medieval Europe.
To 21st-century skeptics who cite the initially beneficent effects of the MWP as proof that global warming is no big deal, Rosen responds by pointing out that the MWP was “a Northern Hemisphere phenomenon … there is still little evidence that worldwide temperatures were, on average, warmer than today.” Moreover, the growth fueled by the MWP proved to be unsustainable.
“More and more marginal land was producing a larger and larger percentage of [Europe’s] food,” the author notes. When those marginal lands ceased to produce due to frosts and floods, the millions of extra mouths to be fed remained. Rebellions and civil wars exacerbated the impact of an unprecedented quarter-century of terrible weather and deadly livestock diseases. Two consecutive harvest failures in 1314 and 1315 launched seven years of famine, resulting in the deaths of between 5 and 12 percent of the population of northern Europe.
Lest we feel too smug about foolish medieval combatants destroying crops and cattle at a time when both were already dangerously decimated, Rosen reminds us that two of the worst famines in history occurred in the 20th century and were almost entirely man-made: Stalin’s forced collectivization program starved to death some 5 million Russians, while as many as 25 million Chinese died of hunger as a consequence of Mao’s Great Leap Forward. At least Robert Bruce’s destructive attacks on the farms of northern England served a strategic purpose: to destroy the food supply and deny the English army the resources it needed to pursue its conquest of Scotland.
As he did in Justinian’s Flea, his wide-ranging account of the bubonic plague pandemic that wracked the Byzantine Empire in the sixth century, Rosen weaves together a vast array of disparate information to create a multi-layered, occasionally scattershot narrative. It’s not entirely clear that Viking raids or William Tell, for example, are all that relevant to the more central (and less familiar) material about the causes and consequences of the Great Famine, but Rosen is a terrific storyteller and engaging stylist; his vigorous recaps of famous battles and sketches of various colorful characters will entertain readers not unduly preoccupied by thematic rigor.
Rosen does make a persuasive case that the period’s perpetual wars prompted government actions that increased the Great Famine’s severity, as when Edward II of England had his tax collectors confiscate civilians’ grain and animal fodder to feed his soldiers, or required hard-pressed rural communities to provide manpower they could not spare to fight wars he could not afford.
The benefits of this inclusive approach are also apparent in Rosen’s analysis of how the lucrative wool trade put humans at risk of starvation: “The fact that wool was worth more than grain meant that pastoral lands dedicated to sheep farming got farther and farther away from those used for cereals … which detached the biggest producers of manure from the lands that needed it most.” When a parasitic worm killed 70 percent of Europe’s sheep in 1321, the townspeople dependent “on the trade surpluses generated by the export of wool to purchase food” were out of luck—and food.
People died in the countryside, too, but Europe’s towns were where the Great Famine assumed its most apocalyptic aspect, captured by Rosen in grim descriptions of corpses piling up in city streets, open pits into which bodies were flung, stories of cannibalism and child abandonment. (The folk tale “Hansel and Gretel” originated in these years.) Rosen’s principal goal, however, is not to horrify us, but to make us think.
“A disaster story about the resonant forces set off by unexpected climate volatility multiplied by nations acting in what they saw as their own short-term interests resonates today,” Rosen says—and indeed it does. While vividly re-creating a bygone civilization, he invites us to look beyond our significant but ultimately superficial differences and recognize that we too live in fragile equilibrium with the natural world whose resources we recklessly exploit, and that like our medieval forebears we may well be vulnerable to “a sudden shift in the weather.”