4.7.2 Changes in Permafrost
18.104.22.168 Data Sources
Although there are some earlier measurements, systematic permafrost temperature monitoring in Russia started in the 1950s at hydrometeorological stations to depths of up to 3.2 m (Zhang et al., 2001) and in boreholes greater than 100 m deep (Pavlov, 1996). Permafrost temperatures in northern Alaska have been measured from deep boreholes (generally >200 m) since the 1940s (Lachenbruch and Marshall, 1986) and from shallow boreholes (generally <80 m) since the mid-1980s (Osterkamp, 2005). Some permafrost temperature measurements on the Tibetan Plateau were conducted in the early 1960s, while continuous permafrost monitoring only started in the late 1980s (Zhao et al., 2003). Monitoring of permafrost temperatures mainly started in the early 1980s in northern Canada (S.L. Smith et al., 2005) and in the 1990s in Europe (Harris et al., 2003).