The EURO-CLIMHIST database: challenges and potentials of a 40-years development to-wards a European-wide cooperation project

The roots of EURO-CLIMHIST date back to the 1980s, when Christian Pfister created a database for his historical climate data on Switzerland. Through an international project funded by the European Science Foundation (1990-1994), the scope developed from a national one to a Europe-wide. However, the maintenance of the database had to be reduced to a minimum for more than a decade afterwards. Finally, the Swiss Federal Meteorological Service MeteoSwiss with the Global Climate Observing System (GCOS) Switzerland enabled a long-term financial support and planning since 2010. In 2015, the database has been made freely accessible to the public. During the last ten years, several fundamental technical updates had to be made, including also the general decision to which extent to include machine learning such as Large Language Models. The enlargement of datasets has been achieved both by including new data from the Bernese research team (including results of students’ PhD, MA and BA theses) and by international cooperation projects (such as teams in the Czech Republic, in Estonia, Finland, Sweden, Ireland, France and Spain). Besides written documentary evidence and early instrumental measurements, EURO-CLIMHIST has also included pictorial evidence (paintings, drawings, photographs) of glaciers in the Alps and in Norway during the last years, a cooperation project with the World Glacier Monitoring Service Switzerland. The paper will show, how these cooperation projects constitute both high-potential and also challenges related to technical issues, regional peculiarities of sources and labour power. This also includes some regional databases lacking the availability to be maintained for the future, which are going to be included into EURO-CLIMHIST.