The series of climatic measurements of surface temperatures in Switzerland date back to the mid-19th century. The average annual temperature increased by 1.6 ° C between 1864 and 2008 compared to the average conditions of 1961-1990. Over the past 100 years (1909-2008), average annual temperatures have increased by 0.12-0.19 ° C over the decades, without any obvious regional differences. In recent decades, rising temperatures have accelerated significantly (1). Austria has experienced an average temperature rise of more than 1 ° C over the last century (25). In Austria, a widespread warming trend in both daily minimum and maximum temperatures has been confirmed for homogenized time series of temperature data covering the period 1948-2009 (31).

Recent studies show that over the past 100 years, there has been a similar trend in the Alps to change the air temperature at low and very high altitudes. The temperature profiles were analyzed for wells drilled in three different sections between 4240 and 4300 m above sea level in the Mont Blanc region (French Alps). The average warming rate was 0.14 ° C / decade between 1900 and 2004. This is similar to the observed low-altitude regional trend in the northwestern Alps, assuming that air temperature trends are independent of altitude (33).

Recent warming in the Alps, which has been around since the mid-1980s, albeit in line with global warming, is about three times the global average. The most significant warming has taken place since the 1990s. In fact, 1994, 2000, 2002 and especially 2003 were the warmest in the last 500 years (7).

The intense warming in the Alps during the 1990s was partly related to the behavior of the North Atlantic Oscillation (NOA). NOA is characterized by cyclical fluctuations in air pressure and changes in storm tracks across the North Atlantic. The NAO is considered to have a particular impact on the climate in the highlands of the Alps (8). The impact of NAO on decadal trends in atmospheric blocking phenomena has been confirmed in a recent study (13).

In the summer of 2003, Central Europe experienced an extremely intense heat. In the north of the Alps, the average summer temperature (June-August) exceeded the long-term average (1864-2000) by more than 5 standard deviations, making summer 2003 the warmest this year. the field of instrumental records began in 1864 (24). The heat of 2003 suggests that climate variability may have increased (12).

Very high temperatures, which set a new historic high in Austria, characterized the European summer of 2013. The most intense heat wave of 2013 over Central Europe in early August was triggered mainly by anticyclonic conditions and was probably exacerbated by previous deficits. Combined with heavy flooding in the Danube and Elbe River basins in early June and heavy convective storms in late July, the hot summer of 2013 in Central Europe may be an analogue of the future summer climate, which is likely to be more susceptible to both. and extreme precipitation (35).

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