Future Climate Change Projections of the Kabul River Basin Using a Multi-model Ensemble of High-Resolution Statistically Downscaled Data

Abstract

In this study, we examined the future climatic changes in the Kabul River basin located in the Hindu Kush Mountain ranges of Pakistan and Afghanistan. We used the latest data set of statistically downscaled CMIP5 Global Climate Models (GCMs), i.e., NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP). The data set delivers valuable local scale, high-resolution climate change information for past and future periods (1950–2100) on a daily basis, which is very suitable for exploring future changes in mean and extremes of both temperature and precipitation. Multi-model ensemble derived from NEX-GDDP data effectively produces observed spatial patterns and magnitude of both temperature and precipitation that otherwise cannot be captured with coarse resolution GCMs. For the historical period (1975–2005), NEX-GDDP presented an improved seasonal cycle climatology and correlation coefficient with the observed data set. Future projections using multi-model ensembles indicate a consistent rise in mean temperature over the entire Kabul River Basin, relative to the baseline under RCP4.5 and RCP8.5 emission scenarios. Although the increase in temperature is not uniform across the domain, upper reaches of the basin show annual and seasonal warming of approximately 6.8 °C by the end of the twenty first century under the RCP8.5 scenario. These changes are significant at a 95% confidence level. The rise in summer and winter temperatures may negatively affect the snow accumulation during winter and has the potential to accelerate glacier melting during summers. Projections of future precipitation under both scenarios show an overall decrease in mean precipitation, particularly under the RCP8.5 scenario.