11.3.3.6 Mediterranean Cyclones

Several studies have suggested a decrease in the total number of cyclones in the Mediterranean Sea (Lionello et al., 2002; Vérant, 2004; Somot 2005; Leckebusch et al., 2006; Pinto et al., 2006; Ulbrich et al., 2006), but there is no agreement on whether the number of intense cyclones will increase or decrease (Lionello et al., 2002; Pinto et al., 2006).

11.3.3.7 Snow and Sea Ice

The overall warming is very likely to shorten the snow season in all of Europe. Snow depth is also likely to be reduced, at least in most areas, although increases in total winter precipitation may counteract the increased melting and decreased fraction of solid precipitation associated with the warming. The changes may be large, including potentially a one-to-three month shortening of the snow season in northern Europe (Räisänen et al., 2003) and a 50 to 100% decrease in snow depth in most of Europe (Räisänen et al., 2003; Rowell, 2005) by the late 21st century. However, snow conditions in the coldest parts of Europe, such as northern Scandinavia and north-western Russia (Räisänen et al., 2003; Shkolnik et al., 2006) and the highest peaks of the Alps (Beniston et al., 2003) appear to be less sensitive to the temperature and precipitation changes projected for this century than those at lower latitudes and altitudes (see also Section 11.4.3.2, Box 11.3).

The Baltic Sea is likely to lose a large part of its seasonal ice cover during this century. Using a regional atmosphere-Baltic Sea model (Meier et al., 2004), the average winter maximum ice extent decreased by about 70% (60%) between 1961 to 1990 and 2071 to 2100 under the A2 (B2) scenario. The length of the ice season was projected to decrease by one to two months in northern parts and two to three months in the central parts. Comparable decreases in Baltic Sea ice cover were projected by earlier studies (Haapala et al., 2001; Meier, 2002).