1540 European drought

The 1540 drought in Europe was a climatic event in Europe. In various palaeoclimatic analyses the temperature and precipitation regimes were reconstructed and compared to present-day conditions.

On the basis of historical records Wetter et al. (2014) derived that during an eleven-month period there was little rain in Europe, possibly qualifying as a megadrought. These conclusions however were questioned by Büntgen et al. (2015) on the basis of additional data (tree rings).

Orth et al. (2016) concluded that in summer 1540 the mean temperature was above the 1966–2015 mean and with a probability of 20% exceeded that of the 2003 summer; however, the study's mean reconstruction suggests that the summer of 2003 was still overall hotter across much of Europe.

Scientific evaluation and discussion
The assumption of a megadrought in the year 1540 is primarily supported by more than 300 contemporary chronicles from across Europe, which consistently describe the effects of prolonged drought and heat, such as a significant precipitation deficit, extremely low levels of major rivers, widespread wildfires, the lowering of groundwater levels (resulting in the drying up of wells), as well as severe consequences for agriculture and livestock farming. Particularly reliable sources include the extensive weather diary of Marcin Biem, the rector of the University of Kraków, whose records allow for the statistical reconstruction of precipitation levels in the Kraków region for the year 1540.

In contrast, a study published in 2015, based on the analysis of growth rings of various European tree species (dendrochronology, also known as tree-ring dating), concluded that the conducted analyses did not provide evidence of an exceptional drought period throughout 1540. In their reply, the authors of the aforementioned study (Wetter et al.) pointed out that growth rings may sometimes incompletely or belatedly reflect hot and dry extremes, emphasizing the fact that discrepancies between instrumentally determined and dendrochronological data have often occurred in recent times during climatic "outliers" (the "divergence problem").

A publication from 2016 assumes that the average summer temperature in 1540 exceeded the corresponding average values of the 1966 to 2015 time series and, with a 20 percent probability, even surpassed the heatwave of the summer of 2003. In this context, the existing uncertainties regarding the available data, which hinder reliable temperature reconstructions for short-term anomalies during the last millennium, were also mentioned.

The weather conditions of 1540 present a paradoxical situation since this exceptional year occurred during the Little Ice Age, which lasted approximately from the early 15th to the mid-19th century. However, the question raised by some studies focuses more on whether this singular event could serve as a "blueprint" for future climatic developments in this geographical context. According to several scientific studies, there has been a clear tendency worldwide towards the formation of warm and dry climates in recent decades. With further warming, the disappearance of existing climate zones and the establishment of new ones in Central Europe will likely occur, similar to what happened at least to some extent almost 500 years ago.

Description
The Swiss historian Christian Pfister described the events of 1540 in a newspaper interview:

"For eleven months, there was practically no rain, temperatures were five to seven degrees [Celsius] [5 - 7 C-change] above the normal values for the 20th century, in many places summer temperatures must have exceeded 40 C. Many forests in Europe went up in flames, choking smoke darkened the sun, not a single thunderstorm was reported in the summer of 1540. Water was already scarce in May, wells and springs dried up, mills stood still, people starved, livestock was slaughtered. Estimates are that in 1540 half a million people died, mostly from dysentery.

Everything began in northern Italy, with a winter that felt like a July. Not a single drop fell from October 1539 to early April 1540. Then the drought advanced north. ... July brought such a frightful ember-like heat that churches made prayers while the Rhine, Elbe and Seine could be waded through without getting one's feet wet. Where there was still water, the warm broth acquired a green colour, and dead fish floated belly-up. Water levels in Lake Constance sank to record low levels, and Lindau actually became connected to the mainland. Soon the surface water had completely evaporated, soils broke up, some dry cracks were so wide that a foot would fit into them. ...

The first grapes were already ripe by 12 August, in Alsace fruit trees bloomed a second time, in Lindau it was actually enough for a second cherry harvest. At Lake Constance and in Bayreuth wine eventually became cheaper than water, and in Limoges winemakers were harvesting roasted grapes, from which they obtained sherry-like wine, which ... made one quickly drunk."

From the city of Münden there is a description of how in the year 1540 the ducal wine from the vineyard at was "so excellent" that it was preferred to foreign wine.

In the Swiss village of, "desperate people went over 500 m up and down in elevation every day, only to fill a few barrels of water in Lake Thun".

City fires
In the year 1540, there was an unusually high number of city fires, surpassing only during the height of the Thirty Years' War, in a year without major war damages. In Einbeck, the Kumme Wasser, a stream flowing through the city, was likely dried up. On "Annentag" (the day of Saint Anne), July 26th, a fire broke out, and the entire city was destroyed in the Einbeck city fire, with between 100 and 500 people dying. There are records of 32 additional city fires in German territory for the year 1540. The fires occurred during a time of political and religious conflicts surrounding the Reformation. In many cases, arson was suspected as the cause of the conflagrations, allegedly motivated by anti-Protestant sentiments. Vagabonds and beggars were often scapegoated, leading to a genuine paranoia regarding arsonists. The year 1540 also became known as the "Mordbrenner-Jahr" (year of arsonists).