Résultat de la recherche
Monthly air temperature trends in Switzerland 1901-2000 and 1975-2004
We analysed long-term temperature trends based on 12 homogenised series of monthly temperature data in Switzerland at elevations between 316 m.a.s.l. and 2490 m.a.s.l for the 20(th) century (1901-2000) and for the last thirty years (1975-2004). Comparisons were made between these two periods, with changes standardised to decadal trends. Our results show mean decadal trends of +0.135 degrees C during the 20(th) century and +0.57 degrees C based on the last three decades only. These trends are more than twice as high as the averaged temperature trends in the Northern Hemisphere. Most stations behave quite similarly, indicating that the increasing trends are linked to large-scale rather than local processes. Seasonal analyses show that the greatest temperature increase in the 1975-2004 period occurred during spring and summer whereas they were particularly weak in spring during the 20(th) century. Recent temperature increases are as much related to increases in maximum temperatures as to increases in minimum temperature, a trend that was not apparent in the 1901-2000 period. The different seasonal warming rates may have important consequences for vegetation, natural disasters, human health, and energy consumption, amongst others. The strong increase in summer temperatures helps to explain the accelerated glacier retreat in the Alps since 1980.
Recent climate change: Rethinking drought in the context of Forest Fire Research in Ticino, South of Switzerland
We analyse trends over the past 32 years in drought variables in the context of forest fire research and climate change in Ticino, Southern Switzerland. January to April and in particular the month of March have become drier. This is the time of the year when forest fires are most frequent. Our results show an increasing trend in all climatic variables favourable to drought and forest fires, including the length of episodes without precipitation, sunshine duration and temperature, and a decrease in relative humidity. The only exception is the number of "foehn" days, which have not significantly increased.