Changes of snowfall under warming in the Tibetan Plateau

Snowfall is a critical part of the hydrological system in high-altitude regions and strongly impacted by climate change. This study uses a threshold temperature method to estimate spatial and temporal variations of snowfall at 71 stations across the Tibetan Plateau from 1960-2014. Regional air temperature and precipitation have increased by 0.039 °C/yr, and 1.43 mm/yr, respectively. While warming rates have been fairly uniform across the plateau, spatial variations in snowfall trends are large, with decreases in the eastern and north-eastern areas but increases at higher elevations in the centre and west. Region wide snowfall increased during 1961-1990 and 1971-2000, but decreased in 1981-2010 and 1991-2014. Wintertime snowfall has increased but summer snowfall has decreased. These divergent trends can be explained because maximum snowfall is recorded at temperatures between 1 and 2 °C. Above/below this threshold snowfall usually decreases/increases with increased warming. Although maximum snowfall temperature is a key factor to understand future snowfall changes, concurrent influences such as changing moisture sources and atmospheric circulation patterns require further research.