In a paper ‘The year-long unprecedented European heat and drought of 1540 – a worst case’ in the journal Climatic Change an international group of 32 scientists shows that in 1540 Western Europe suffered a heat wave and ‘Megadrought’ that were probably worse than the European heat wave of 2003. They also determined that even the best current climate models can’t simulate so severe an event. The abstract:
The heat waves of 2003 in Western Europe and 2010 in Russia, commonly labelled as rare climatic anomalies outside of previous experience, are often taken as harbingers of more frequent extremes in the global warming-influenced future. However, a recent reconstruction of spring–summer temperatures for WE resulted in the likelihood of significantly higher temperatures in 1540. In order to check the plausibility of this result we investigated the severity of the 1540 drought by putting forward the argument of the known soil desiccation-temperature feedback. Based on more than 300 first-hand documentary weather report sources originating from an area of 2 to 3 million km2, we show that Europe was affected by an unprecedented 11-month-long Megadrought. The estimated number of precipitation days and precipitation amount for Central and Western Europe in 1540 is significantly lower than the 100-year minima of the instrumental measurement period for spring, summer and autumn. This result is supported by independent documentary evidence about extremely low river flows and Europe-wide wild-, forest- and settlement fires. We found that an event of this severity cannot be simulated by state-of-the-art climate models.Unfortunately, the single-article cost is $39.95, which is more than I’m willing to pay, so for the details below the disembodied paraph I’m relying on the report in SPIEGEL ONLINE.
The group compiled evidence from more than 300 documents, including records kept by farmers, churches, and lock keepers.
South of the Alps the disaster started in 1539. By October processions supplicating God for rain were being conducted in Spain, and an Italian chronicle describes the winter weather as being as dry and warm as in July. The drought spread north early in 1540; an Alsatian vintner noted that there were only three days of rain in March. The soil dried out and cracked; according to one chronicle, you could dangle your legs in some of the fissures. This resulted in a positive feedback cycle that stabilized the heat wave: less water available for evaporation meant less cooling of the air and hence more drying out of the soil.
And the heat wave was ferocious. The number of days with temperatures over 30°C (86°F) was at least three times as great as usual. Wells and springs dried up that had never done so before. A Swiss chronicler reported that not a drop of water could be found even a metre and a half below the beds of many streambeds. Even some major rivers became small enough to be crossed on foot. In 2003 the volume of water in the Elbe river was about half the usual amount; the researchers estimate that in 1540 it was only a tenth of the usual amount. Middle Europe as a whole is estimated to have received only about a third as much precipitation as usual.
The human consequences were terrible. Thousands died of dysentery from drinking contaminated water. Many animals died, either of thirst or of heat stroke. Agricultural workers collapsed in the fields and vineyards. Tempers flared, and violence surged. The harvest was of course very meagre, and the price of grain and bread went through the roof. Forest fires and bush fires broke out all over and spread to the towns, and smoke covered the continent.
The causes of the 1540 catastrophe are unclear; plainly modern climate change is not the culprit. What is clear is that such extreme heat waves are more likely now than ever before in human history. Christian Pfister of the University of Bern observes that a repetition of the drought and heat wave of 1540 would have dramatic consequences today on agriculture, transportation, and human health: ‘The catastrophe of 1540 should be a reminder of what can happen.’ He notes, however, that no one is prepared for anything so extreme.