Projected Climate Change in the Hindu Kush-Himalayan Region By Using the High-resolution Regional Climate Model PRECIS

The Hindu Kush-Himalayan (HKH) region is characterized by a variety of climatic conditions from tropical to alpine. It has been documented that the rates of warming in the HKH region are significantly higher than the global average and that the warming is occurring at much higher rates in the high-altitude regions than in the low-altitude regions. Mountainous environments are considered sensitive indicators of climate change. Hence this study examined the potential impact of global warming on the HKH region by applying Hadley Centre's high-resolution regional climate model PRECIS (Providing Regional Climates for Impact Studies) to 3 subregions: the western, central, and eastern Himalaya. The physical mechanisms that drive warming are different for the 3 regions, and the western Himalaya has 2 major rainy seasons, whereas the central and eastern Himalaya have only one. This study therefore focused on the common rainy season (June-September), during which all 3 regions receive the highest proportion of their annual rainfall. The 3 PRECIS simulations that correspond to the Intergovernmental Panel on Climate Change's A1B emissions scenario were carried out for a continuous period from 1961 to 2098. They were validated with high-resolution (0.25 degrees latitude x 0.25 degrees longitude) data provided by the Asian Precipitation-Highly Resolved Observational Data Integration Towards Evaluation of the Water Resources (APHRODITE) project and by the US National Centers for Environmental Prediction and National Center for Atmospheric Research (NCEP/NCAR) reanalysis data. The model was reasonably effective in simulating the monsoon climate over the HKH region. The climate projections were examined over the short (2011-2040), medium (2041-2070), and long term (2071-2098). The model projections indicate that significant warming will occur throughout the HKH region toward the end of the 21st century. Summer monsoon precipitation is expected to be 20-40% higher in 2071-2098 than it was in the baseline period (1961-1990). The 3 Quantifying Uncertainty in Model Predictions simulations show large differences in projections in the western Himalaya.