The winter is shrinking and the overall precipitation during the season, particularly snow, is decreasing at an alarming rate in the “Queen of Hills”, making a White Christmas and a White New Year for which it has been famous, a rarity in recent years.
The disastrous impact of excessive and unregulated construction and indiscriminate felling of trees on the fragile hill environment has been brought out for the first time by a study conducted by scientists of the Meteorological Department. The winter in Shimla, which extended from November to March until the mid-1980s, has shrunk drastically. While climate change in the normal course is a slow process and a minimum period of 30 years has to be studied to draw conclusions, the weather pattern has undergone a sea change in the erstwhile summer capital of India since 1991 with the snow season shrinking at a rate of 11 days per decade.
The decadal average precipitation from December to March has declined from 283.9 mm (1991-92 to 2000-01) to 235.1 mm (2001-02 to 2010-11) and the percentage of snowfall to total precipitation has also come down from 39 to 30. The decadal average of snow has plummeted from 109.4 mm to 68.1 mm. More importantly, the pattern of snowfall is also changing and snowfall has been decreasing in December, January and March and the maximum precipitation is being recorded in February.
The research paper by S.C. Bhan and Manmohan Singh published in the Journal of Agro-meteorology reveals that the quantum of snow has come down and most of the precipitation was in the form of rain. The total precipitation has declined from 28.3 mm to 25.8 mm in December but snowfall decreased drastically from 9.9 mm to 1.4 mm. Similarly, the precipitation (snow) declined from 85.9 mm to 54.9 ( 49.5 mm to 26.1 mm) in January , from 87.2 mm to 82 mm (8.2 mm to 5.3 mm) in February and from 82.5 mm to 72 .4 mm (8.2 mm to 5.3 mm) in March. The seasonal total precipitation and snow showed a decrease of 90 mm and 57 mm per decade, respectively.
The average beginning of snowfall was found to be January 1 (latest January 20) and the average cessation of the season February 21(latest March 26), which explains why snowfall has been eluding the hill station on Christmas and New Year’s Eve. The average number days with snow in the season has come down to 8.2, with a maximum of 3.0 days in February. The highest number 20 days was recorded in the 1994-95 season. The snow season has shrunk as is evident from the fact that the average duration between the first and last snowfall has come down from 58.6 days (1991-2000) to 44.4 days (2001-2011).
The two meteorologists conclude that the change in the weather pattern will affect the river flows which in turn have an adverse impact on agriculture and horticulture in the region.