Air temperature changes until now
Climate measurement series of ground-level temperatures in Switzerland date back to the mid-19th century. The mean annual temperature has increased by 1.6°C between 1864 and 2008 with respect to 1961-1990 average conditions. Over the past 100 years (1909-2008), mean annual temperatures increased by 0.12-0.19°C per decade, with no distinctive regional differences. Temperature increase has accelerated substantially in recent decades (1). An increase of more than 1°C in average temperature has been observed in Austria during the last century (25). For Austria, a widespread warming trend in both daily minimum and maximum temperatures was confirmed for homogenized time series of temperature data covering the period 1948–2009 (31).
Recent research suggests that there is a similar air temperature trend in the Alps at low and very high altitudes over the last 100 years. Temperature profiles have been analyzed from boreholes drilled at three different sites between 4240 and 4300 m above sea level in the Mont Blanc area (French Alps). A mean warming rate of 0.14 °C/decade between 1900 and 2004 was found. This is similar to the observed regional low altitude trend in the north-western Alps, suggesting that air temperature trends are not altitude dependent (33)....
