Long-term variation in snow depth and duration in northern Eurasia
The changes in snow cover have not been the same everywhere. Over the North American Arctic, the duration of snow cover and snow depth have decreased consistently since around 1950. Over northern Europe and Siberia, snow-cover duration has been decreasing since around 1980, but snow depth is not consistently decreasing.
In northern Russia, snow is actually settling earlier, rather than later in autumn. This has lengthened the period of snow cover by two to four days since 1972.
Winter snow depth is also increasing in some parts of the Eurasian Arctic. Over Russia, the number of days each year with snow more than 20 cm deep increased between 1966 and 2007. In western Siberia and the coast of the Sea of Okhotsk, snow has been this thick for around a day longer for every year since 1966.
The increasing snow depth in the Eurasian Arctic, and the earlier snowfall over northern Russia may be partly caused by the dramatic retreat in summer sea ice in the Eurasian part of the Arctic Ocean. This has exposed more open water at the end of the summer, increasing evaporation from the ocean to the atmosphere, resulting in more humid air and greater snowfall further south. There have also been changes in weather patterns, with more frequent and more intense low pressure systems over northern Europe in recent years, linked to greater snowfall.