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Abstract:
Climate extremes can lead to heat waves, droughts, floods that in turn threaten the water and food security in agriculture-based country like Pakistan. This study is designed to investigate the climate extremes trends over different agro-ecological zones (AEZs) of Pakistan. For this purpose, the temperature and precipitation extreme indices have been calculated for the time period of 40 years (1980-2019) using meteorological data of 40 stations. The results indicate the trends in annual means of cool nights (-1.73) and cold spells duration (-1.28) decreased significantly while the indictors of average temperature (0.21), hottest nights (0.24), warm spells duration (1.03), tropical nights (3.39) showed significant positive trends. The spatial distribution depicts that the magnitude of positive trend is considerably high in the southwestern and central parts while negative trend is observed in almost all northern parts. All the precipitation extreme indices present the increasing trends with significant increase 5.04 and 0.85 mmdecade-1 in annual total precipitation and monthly maximum consecutive 5-day rainfall respectively. The weather stations in north and in subhumid environments received more precipitation than the rest of country. The principal component analysis showed a robust increase in the intensity and frequency of extreme temperature and precipitation indices with a total variance of 95.40% and 93.80% respectively. The large-scale atmospheric circulation patterns derived from ERA-Interim reanalysis showed major influence on the shifts in temperature and precipitation extremes in the region. The findings of current study will help to address the issues of climate induced disasters in different AEZs of Pakistan.
