Abstract
In this study single station and zonal data sets from 1976 to 2005 have been analysed to examine the changes and trends in winter mean minimum temperatures of Pakistan. Statistical tests were applied to determine trends in data for different zones of the country. The student’s t – test was used to find the significance of the variation. The variations were found different for different locations and regions but generally the trend of minimum temperatures was found to be increasing, especially in the big cites of Pakistan. Zone-1 that comprises of the hilly stations show an increasing trend in the minimum temperature, while Parachinar which also lies in the zone-1 shows significant decreasing trend. Zone-2 includes stations between 31°N 34°N. Increase in minimum temperature has been observed for this region. Zone-3(a) located in the south western border of the country. Most of them are mountainous stations with high elevations from mean sea level. In zone-3(a) minimum temperature shows slightly increasing trend, although negligible. Zone-3(b) includes the station with high maximum temperature. All the stations except Barkhan and Sukker show an increasing trend in minimum temperature. In Zone-4 the variation in temperature is not significant except for the Karachi station. Country wide analysis shows that there is slight increase in mean minimum temperature; however the increasing trend is weak. Increase in the mean minimum temperature is an indicator of climate change. It is evident that in the big cities and plain areas of the country changing behaviour of winter will bring in to action different health and agroenvironmental challenges.