2. Recent Climate Change over High Asia

Though elevated regions have generally been spotted as climate change hotspots due to amplified signal of change observed over recent decades, such evidence for the Tibetan Plateau and its neighboring regions is supported only by a sparse observational network, less representative for the high-altitude regions. Using a larger database of widely used gridded observations (CRU and UDEL) and reanalysis datasets (NCEP-CFSR, ERA-Interim, and its downscaled variant ERA-WRF) along with high-quality homogeneous station observations, we report recent changes in mainly the mean monthly near-surface air temperature and its elevation dependence, as well as changes in precipitation over the Tibetan Plateau, its neighboring mountain ranges, and the basins of major rivers originating from them. Our station-based analysis suggests a well-agreed warming over and around the Tibetan Plateau, which is more pronounced mainly during winter and spring months and generally in agreement but higher in magnitude than that of previously reported. We found a varying skillset of considered gridded and reanalysis datasets in terms of suggesting robust spatial and elevation-dependent patterns of trends and their magnitudes. The UDEL, ERA-Interim, and CRU datasets, respectively, exhibit high- to medium-level agreement with the station observations in terms of their trend magnitudes, which are generally underestimated. We found that all datasets agree with station observations as well as among each other for a strongest warming and drying in March over the northwestern region, for wet conditions in May over the southeastern Tibetan Plateau and Myanmar regions, as well as for the general warming pattern. Similarly, a strongest EDW rate per 1000 m elevation found in January is well agreed qualitatively among all datasets, except ERA-WRF. We also confirm high inter-dataset agreement for higher warming rates for highlands (above 2000 m asl) as compared to lowlands in December and January and with a mild agreement during the growing season (April–September). Except for winter months, NCEP-CFSR reanalysis largely contradicts the elevation-dependent warming signal. Our findings suggest that well-agreed likely changes in the prevailing climate will severely impact the geo-ecosystems of the High Asia and will have substantial influence on almost all dimensions of life in the region.