Multi-model cropping seasons projections over pakistan under representative concentration pathways

Abstract

This study examines the changes in soil moisture derived from 24 global climate model (GCM) simulations of Coupled Model Intercomparison Project phase 5 (CMIP5) over the cropping seasons (Kharif and Rabi) of Pakistan from 2021 to 2050. The comparison of historical run with reanalysis global land data assimilation system for the period 1971–2000 have shown that the soil moisture conditions in Rabi season were well captured by most of the CMIP5 GCMs as compared to Kharif. The historical and projected temporal trends of soil moisture showed slightly decreasing trend in soil moisture during Kharif under representative concentration pathways (RCP) 8.5 while Rabi depicted a well-marked declining trend under both the RCPs (4.5 and 8.5) from 1951 to 2050. The decadal and mean near future projections for Kharif and Rabi had been analyzed from 2021 to 2050. Kharif showed soil moisture stress (−3 to −9 %) in the decade 2041–2050 whereas Rabi projected the decrease in soil moisture (−5 to −15 %) in all the three decades (2021–2030, 2031–2040 and 2041–2050) by RCP 4.5 which was then further amplified (−5 to −20 %) under RCP 8.5. The mean projections also showed the negligible decrease in soil moisture during Kharif and severe soil moisture stress over the southern parts of Pakistan specifically south western areas of Balochistan, Khyber Pakhtunkhwah, southern Punjab and southern Sindh. In order to support the soil moisture changes over Pakistan crop land the decadal and mean evaporation of water from the soil projections also showed decline (−4 to −12 %) in Kharif and extreme drop (−6 to −24 %) in water evaporation from soil under both the RCPs. In nut shell the study clearly indicates the intensification of soil moisture stress in near future during Rabi season in Pakistan.