Iceland and Greenland were settled during what is usually referred to as the ‘Medieval Warm Period’. Not long afterwards, the climate started to deteriorate, culminating in the ‘Little Ice Age’ of the 15th and later centuries. This paper examines the extent to which medieval Icelandic writers were aware of how much weather conditions had deteriorated between the early days of the Settlement and the period in which they themselves lived.
Konrad of Megenberg’s Book of Nature (Buch der Natur) is the first larger treatise on nature in Middle High German. Due to his easily understandable explanations of scholastic thought, it became widely spread. Konrad combines translations of the most important scholastic scholars, such as Albertus Magnus, Thomas Aquinas or Thomas of Cantimpré, with popular thoughts. In this way, he might be representative for the knowledge on nature in general and weather in particular during the 14th century. In his work, he explains, why earthquakes take place, based on his experiences from the 1348 earthquake in Northern Italy and Southern Austria. He describes the origin of hail, of bloody rain, of clouds in great detail and remarkably exactly. He also focuses on comets and their impact on history and society.
With the rise of the Franciscan school of thought in Oxford after the mid-thirteenth century, an interest in meteorology was awakened amongst the scholars. This went hand-in-hand with studies in astronomy and aimed at developing forecasting skills. In this scientific environment – which emphasised the need for observation, hypothesis and experimentation – the earliest European weather diaries were initiated. The surviving fragments are short texts recording weather on a daily basis or summarising the meteorological character of a month. Two out of these three weather records were written in the margins of astronomical tables. The third is the most comprehensive and longest of the diaries, covering the years 1337 to 1344. It can be attributed to William Merle, a provincial rector with strong connections to Oxford. Merle recorded precise descriptions of rainfall, temperature and wind force as well as wind direction. These meticulous observations were the backdrop against which he wrote two treatises on weather forecasting. Merle’s weather diary can today be verified with comparisons with weather references in contemporary narrative and administrative sources, as well as with now available climate proxies in the form of tree ring data or the date of the grain harvest.