Effects of Medieval Climate Change

In south central England, ... the century from 1180 to 1280 had been the medieval golden age because of favorable climatic conditions. The climate of the northern hemisphere, including England, experiences alternating cycles of warming and cooling. A warming trend had set in during the early twelfth century and it reached its height in the century after 1180. It was a time of long, warm summers and moderate winters. There always seemed to be enough rain to make the cereal crops sprout fervently. There were no crop failures or famines....

The downside of good weather and sharply rising population was an unprecedented boom in agricultural real estate. The thirteenth century in England was a time of land hunger.... Millions of acres were deforested and settled with peasant villages....

Climatic cycling continued to drive social and economic change. Around 1280 the warming trend began to run down. A new weather cycle unevenly but visibly intruded into rural England. Summers became cooler and shorter, the long autumns ideal for bringing in the lush crops truncated. Winters became longer and more harsh. The cooler period was to last until the late fifteenth century, when it would be followed by another warm century and then the "little ice age" of the seventeenth century, when people actually skated on the frozen Thames--not something you would want to try today.

In the summers of 1316 and 1317 rural disaster struck. The sun did not shine. There were widespread crop failures. There was famine and death from hunger. These terrible years had a special cause. Huge volcanic eruptions in Indonesia threw continent-sized clouds of ashes into the atmosphere and by 1316 this cloud of unbeing had reached England. Even when the sun shone again and the famine subsided, there were adverse weather conditions--too much rain--for good cereal harvests. The price of grain escalated. The stomachs of the peasants were no longer full....

It may be speculated that the Great Famine and global cooling of the early fourteenth century and the deterioration in the diet of the common people that resulted had some adverse impact on public health. Undernourished bodies were more easily prey to the Black Death.

SOURCE: In the Wake of the Plague: The Black Death & the World It Made, by Norman F. Cantor (Harper Perennial, 2002), pp. 67-68, 74-75