Pfister has gradually expanded and methodically refined the database. Today (2019), Euro-Climhist is the largest climate history database with over 200,000 records. Agricultural history Agricultural-historical topics occupy a large space in Pfister's writings, since they are closely linked to climate history and population history. He distinguishes four agricultural utilisation zones in Old Swiss Confederacy: the cereal-growing area in the Swiss Plateau, the pastoral area in mountainous areas, a zone of mixed field-grass cultivation in hilly areas, and areas of intensive viticulture. The main focus of his analysis and models is on cereal production. In this context Pfister has worked out the importance of the nitrogen cycle for productivity development. 3 Population history Since Erich Keyser’s Population History of Germany (Leipzig, 1938) no synthesis had been written for German speaking areas in the Early Modern Period. At the beginning of the 1990s, Christian Pfister took on the task of collecting and compiling a hardly comprehensible number of small-scale, at best regional and heterogeneous studies worked out over half a century, and to press them into the framework of a small volume of the Encyclopaedia of German History. Regional history Both Christian Pfister’s dissertation (1974) and his habilitation thesis (1984) were committed to the histoire totale of the Annales School in addition to climate history. His focus on the Canton of Bern opened up a field of regional history that continued to occupy him in the years that followed. Through the fine division of its landscape, the Canton of Bern offers a patchwork of zones which followed different paths in their development. Pfister’s monograph "Im Strom der Modernisierung" (Bern, 1995) meets the methodological postulate of a histoire totale with extraordinary precision and spatial-temporal differentiation; and can be regarded as a material history in the best sense of the word, in which energy sources and food, agricultural production methods and their modernization appear just as much as the people who give birth, eat, work, argue, invent, try, age and die, and are not only processed into statistical series of numbers. Concurrent to Climhist, Christian Pfister set up the BERNHIST regional history database from 1984. In 2009, the database contained around 1.5 million individual data from the fields of population, economy, environment and politics for the period from 1700 to the present. In 2019, a modernized version of BERNHIST was launched. Environmental history Based on its energy base (biomass, coal, oil, and gas), Pfister