Causes of the unprecedented freezing disaster in January 2008 and its possible association with the global warming

The unprecedented disaster of low temperature, persistent rain, snow and ice storms, causing widespread freezing in the Yangtze River basin and South China in January 2008 is not a local or regional event, but a part of the chain events of large-scale low temperature and snow storms in the same period in Asia. Its severity and impacts were most significant in South China. The event was characterized by three major features: (1) snowfall, freezing rain and rainfall, the three forms of precipitation coexisted with freezing rain being the dominant factor responsible for this disaster; (2) low temperature, rain and snow, and freezing rain exhibited extremely great intensity, with recordbreaking measurements logged down for 8 meteorological elements based on the statistics made by China National Climate Center and the provincial meteorological services in the Yangtze River basin and South China; (3) the disastrous weathers persisted for an exceptionally long time period, unrecorded before in the observation history of China.There is no single cause for this event. It may be resulted from multiple factors that superimpose on and interweave with one another at the right time and place. Among them, the La Nina situation is a climate background that provided conducive conditions for the invasion of cold air into South China; the persistent anomaly of the atmospheric circulation in Eurasia is the direct cause for 4 rounds of cold air invasion into South China; and the northward transport of warm and moist airflows from the Bay of Bengal and the South China Sea finally warranted the formation of the freezing rain and snow storms and their prolonged dominance in the southern part of China.A preliminary discussion of a possible association of this disastrous event with the global warming is presented. This event may be viewed as a short-term, regional perturbation to the global warming trend. There is not any possibility for this event to divert the long-term trend and the global pattern of the global warming.