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Hans-Joachim Dammschneider has written a book about the climate history of the Southern Harz region. In the historical weather data, he discovered climatic fluctuations that should not exist according to the inter -state body for climate change (IPCC).
Long before industrial CO2 has accumulated in the atmosphere, there were already changing warm and cold phases.
The so -called medieval warm period (MWP) has been the subject of scientific debate for years. It is not so much a question of whether this warm time actually took place in Europe, but how it happened. Was it a local phenomenon that was limited in time and was mostly limited to Europe, or was it a time of intensive climate change that also had a global effect?
One thing is certain: from around 950 AD to Germany, a temperature increase of at least 300 years rose, which led to a pronounced warm phase that was cheap for agriculture and life. From the beginning of the 14th century, however, this period was replaced by a relatively fast temperature drop and climatic turbulence towards the so -called small ice age.
In the early reports, the IPCC (1990, AR1) still dedicated a lot of attention to the MWP. However, this focus over the years, and in the latest rating (2021, AR6) the medieval warm time was only given a little space. Studies often even wonder whether it was a global phenomenon. However, a mapping of the available scientific publications (from 2022), which was initiated by S. Lüging, shows that the warm time has certainly left evidence on continents.
From the point of view of natural and cultural history, many reports show that Germany was in a phase of intensive cultural and economic growth of around 1,000 AD. This time is characterized by the establishment of numerous cities, the expansion of the agricultural country and the strong population growth. The forests were clarified, tree methods influenced and increasing temperatures and the resulting positive agricultural economy contributed to prosperity.
Of course, there were no scientific methods to record the weather, but modern climate research uses so -called “proxies” to derive the climate arameters of the time. For example, the cultivation of figs north of Cologne, successful wine production to Schleswig-Holstein and (overall) the Pfister index, which results from numerous characteristics, indicate a longer phase of mild temperatures and favorable climatic conditions. Climate-numerical backward simulations basically confirm this “warm time”.
Historically, periods were often periods in which life bloomed – an idea that plays a rather ambivalent role in the climate debate for the 21st century.
The example of Weischer Koldery The landscape of the southern Harz monastery shows the solid consequences of the MWP: the recovery of swampy areas, the development of the upper Harz water management system, the promotion of mining and the intensive use of wood for construction and energy purposes are just a few examples.
However, this phase of monastic prosperity between 1130 and 1300 AD was apparently completed by a quick drop in temperature. The beginning of the “small ice age” brought very unpleasant weather conditions, which lasted until the end of the 18th century. Already at the beginning of the 14th century, the country was hit by destructive rainfalls and floods (“Schluchtenreis” / Magdalenen flood), failed harvest followed intensive drought (Dante Anomaly) and devastating plagues with millions of deaths in epidemics partially destroyed. These instabilities and difficulties, which were determined/induced not least by the climate, certainly had devastating effects on the livelihood of the monasteries in the South Harzz region. They led to considerable inner crises (including the loss of converts and lay brothers) and ultimately to the end of the huge group of monastery (with the task of large areas of the Harzerz mining industry) in the 15th century.
If this was the case, which overarching climatic processes contributed to this? It can be assumed that in addition to the temperatures, other factors such as the duration of the sunshine also played an important role under the living conditions: the sun actually seems to have been the factor of the MWP, while CO2 is that of modern times.
The latest analyzes and the AMO index (Atlantic Multidecadal Oscillation), which can be traced back to 900 AD, show that the energy influences of cyclical SST (sea surface temperature) from the Atlantic can have a significantly influenced cloud cover and thus the sunshine duration and temperatures in Europe. These interactions were also important for the southern Harz and Waceenried. Can reviews of current climatic processes indirectly allow conclusions to be drawn about earlier physical and social changes with the associated promotion and descent phases between 1000 and 1400 AD?
The present study examines these questions and attempts to draw conclusions for the interactions of the medieval climate from large -scale processes of potential “teleconia” and oceanic cycles. Among other things, the book is intended as a sequence of steps that help to better understand the complex interrelationships of medieval climate change. It shows which “natural” parameters could have contributed to the rise and fall of the vaulted monastery. “
Hans-J. Dammschneider (2025)
Climate history of the southern Harz monastery landscape – Walkenried monastery
ISBN 9783759779878, 106 Pages, Hamburg/Norderstedt 2025
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