Historical and Projected Shift in Agro-Climatic Zones and Associated Variations of Daily Temperature and Precipitation Extremes using CORDEX-SA over Pakistan

摘要

Agro-climatic classification systems based on aridity help to distinguish various features of aridity in different agro-climatic regions around the world revealing potentially serious implications for water and agriculture sectors in light of climate change. This study probed historical and projected variations and shifts in agro-climatic zones associated with dispersion in Probability Density Functions (PDF) for daily temperature (Tmax and Tmin) and precipitation extremes over Pakistan. In this study, a single-model RCM simulation and projection from the output of the Coordinated Regional Climate Downscaling Experiment for South Asia (CORDEX-SA) data were used to evaluate these parameters for three-time spans: near future (2011–2040), mid future (2041–2070), and end of century (2071–2100); each under two different Representative Concentration Pathways (RCP 4.5 and RCP 8.5) after bias-correction for the observed baseline data (1971–2000). The data was collected from 49 weather stations. Future projections based on the used Regional Climate Model (RCM) predicted major changes in extremely arid and semi-arid zones of Pakistan in the future. In terms of statistical moments, the highest magnitude change was noted in the median and mean of the Tmax which increased as much as 5.1?°C, and the 90th percentile of the Tmin increased by up to 6.5?°C under the RCP8.5 by the end of this century in arid and the extremely arid zones. Similarly, the greatest magnitude of change in the precipitation was projected to increase more than 3.3?mm/day under RCPs 4.5 and 8.5 in semi-arid zones by the end of the present century. Projected shifts in agro-climatic zones are coupled with associated changes in the statistical moments of the PDFs for drought and extreme precipitation events in agro-climatic zones in response to climate change.