Difference of total precipitation and snowfall in the Upper Yangtze River basin under 1.5 °C and 2 °C global warming scenarios

The influence of climate change on regional-scale precipitation is becoming undeniable, and can lead to increased flood and drought risks in some regions. The study assessed the potential effect of global warming of 1.5 degrees C and 2 degrees C on total precipitation and snowfall in the Upper Yangtze River Basin (UYRB) based on General Circulation Models (GCMs). Seven total precipitation and six snowfall indices were employed in this analysis. The results show that the annual precipitation (PA) in the UYRB will increase by approximately 4.5-5% and 9-13% per 1.0 degrees C under the 1.5 degrees C and 2 degrees C warming, respectively. Spatially, the PA is shown to increase across the northern part of the basin, but decrease in the southern part. Relative to the baseline period (1986-2005), the frequency of trace and moderate precipitation days shows a decreasing trend, while that of heavy and intense precipitation days will increase under both 1.5 degrees C and 2 degrees C warming scenarios. Moreover, it varies among significance levels of trace, light, moderate, heavy and intense precipitation frequency under 1.5 degrees C and 2 degrees C warming for different Representative Concentration Pathways (RCPs). Unlike overall total precipitation, the annual snowfall (ASF) will decrease by approximately 2.5-8% per 1.0 degrees C under the 1.5 degrees C warming, and the 2-4% per 1.0 degrees C under the 2 degrees C warming. The ASF exhibits a decreasing trend in most of the UYRB except for the far northern part under all global warming scenarios. The date of first snowfall is modeled to be delayed and that of last snowfall will advance, which will lead to the decrease of snowfall days by about 15-20 days under different warming scenarios. In a warming world, total precipitation in the UYRB will increase and snowfall will decrease, which may increase the risk of flood in the future, and more attention should be paid.