In the light of our current worries about climate change and global warming, this is the first a series of articles for Deposits that will cover significant climate changes that have occurred in the geological past and times when the earth’s climate was hugely different from what we know today. However, this first one covers a slightly more recent event – the Medieval Warm period.
The twenty-first century has had some of the hottest temperatures on record, but there was another period that was just as warm or warmer. The Medieval Warm Period (approximately 900–1300 AD), refers to the time when temperatures in Europe and nearby regions of the North Atlantic are thought to have been similar to, or in some places exceeded, temperatures of the late twentieth century. Researchers believe changes in the circulation of the Atlantic Ocean brought warmer waters to the North Atlantic and neighbouring regions, causing warming temperatures. The Medieval Warm Period was followed by the Little Ice Age (approximately 1300-1850 AD), a period of cooling that brought colder winters and advancing glaciers to parts of Europe and North America that lasted well into the nineteenth century.
Scientists have evidence of this unusual warming period through indirect estimates of temperatures based on climate indicators that include tree rings, Greenland ice cores, ocean sediments and, in certain regions, written evidence of crop yields. There are even recorded dates when leaves come out and when flowers bloom in the spring. Records show that Norse people colonised ice free areas of Greenland because of the unusually warm weather. In England, grapes were grown several hundred kilometres north beyond their current growth range.
The resulting climate change supported innovations in agricultural technologies and practice that triggered a revolution in agriculture, improving conditions for Medieval society during the eleventh and twelfth centuries. These changes in the agricultural sector were significant milestones in human civilization.
Violence and threats from Viking, Muslim, and Magyar raids during the previous 200 years led many peasants to leave their home farms, which were widely separated and clustered near the homes of warlords who provided more consistent protection. By the middle of the eleventh century, the invasions from the south, east and north had either slowed or stopped, but the shift to communal living, with its villages and towns, remained. Collective farming developed as small farmers moved into small communities where they shared labour, skills and resources. These collective farms resulted in villages that ranged in size from a handful of individuals to as many as 2,000 people. The land these villages were built on belonged to the king and were administered by feudal warlords, but the peasants – most of whom had become serfs – performed agricultural work.
This collective farming utilised a three-field crop rotation system, where one-third of the fields remained fallow and the other two fields were planted. Crop rotation was a major innovation and provided an essential control on soil exhaustion. Changes in agricultural practice included the sowing of seeds: spring crops (barley, oats and beans) were sown in April; and winter crops (wheat and rye) were planted in the Autumn.
Another important innovation was a switch from using oxen to using horses in farming. Horses could pull heavier ploughs and made farming more efficient. The utilisation of horses stimulated the invention of the padded collar and horseshoes, which gave horses better traction as they pulled ploughs. The construction of the heavy-wheeled plough was an innovation that made a long, deep furrow that cut the wet soils – an essential addition to the panoply of agricultural technologies. Waterwheels and windmills were significant changes that used rotating grindstones that ground grain into flour.
These new technologies and practices in agricultural production, in conjunction with an anomalously warm climate, brought a dramatic increase in crop yields and a considerable increase in northern Europe’s food production. The cumulative effect of these agricultural innovations and the clement climate created annual food surpluses that directly improved the lives of medieval peasants by giving them a higher level of health, better and safer living conditions, and even a bit of free time to attend religious or village festivals. Because of the revolution in agriculture and the increased food supply, populations grew. Many people settled in towns or cities. It would be in these cities that a new era began – the Renaissance.