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COMSATS University, Islamabad. (2019)

Assessment of Variations in Aridity and Climatic Extremes over Agro-diversified Region of Pakistan in Changing Climate

Haider, Sajjad

Titre : Assessment of Variations in Aridity and Climatic Extremes over Agro-diversified Region of Pakistan in Changing Climate

Auteur : Haider, Sajjad

Université de soutenance : COMSATS University, Islamabad.

Grade : Doctor of Philosophy (PhD) Meteorology 2019

Résumé partiel
Assessment of Variations in Aridity and Climatic Extremes over Agro-diversified Region of Pakistan in Changing Climate The observed, simulated, and projected extreme climate indices from the daily observed dataset for several meteorological stations as well as NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) dataset have been explored. The NEX-GDDP dataset is an extension of the General Circulation Model (GCM) runs, performed under the Coupled Model Inter-comparison Project Phase 5 (CMIP5). Two greenhouse gas emission scenarios have been considered, known as Representative Concentration Pathways i.e. RCP4.5 and RCP8.5. The core climate indices, proposed by the Expert Team on Climate Change Detection and Indices (ETCCDI), were used for the investigation of climatic extremes over different provinces of Pakistan. Results show that summer days have significantly increased in Gilgit Baltistan and Azad Jammu Kashmir (GB–AJK) region by 24 and 18 days respectively. Moreover, the projected climate shows an increase of 6 days in the frequency of summer days in the GB-AJK region in the next 30 years. The frequency of heavy precipitation is significantly increasing in Khyber Pakhtunkhwa (KP) province, which may augment the flood hazard in the region. Future projection shows an increase of 1.3°C in the mean maximum temperature in the KP province by the year 2045. An average increase of 1.9°C in the mean minimum temperature has been observed in the Punjab province over the past 54 years ; whereas, there is a projected increase of 1.4°C in the mean minimum temperature in the next 30 years. Such an increasing trend in the mean minimum temperature may impact the food and agriculture sectors in the Punjab province. The results showed a significantly increasing trend in the mean maximum temperature and summer days in the Sindh province, which may enhance the frequency and intensity of heatwaves in the region. There is a projected increase of 20 days in summer days in the Sindh province. A similar rising trend in the temperature have been observed in Balochistan province, which may ultimately enhance the dust and sandstorms in this region. The reduction in rainfall amount, cloud cover, vegetation,complex topography, and urbanizationis one of the xii major reasons for the increase in temperature in KP, GB-AJK Punjab, Sindh, and Balochistan. Agro-climatic classification based on aridity indices helps to identify different features ina region. For climate change, varying features of aridity over different agro- climatic regions around the world have revealedextended implications for the water and agriculture sectors. This study has further probed into the historical and projected 21 st- century variations and shifts in the diverse agro-climatic zones with associated dispersions in Probability Density Functions (PDFs) for daily temperature extremes (i.e. both maximum, minimum) and precipitation over Pakistan.

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