During the first ten months of 2012, above average temperatures affected most of the globe’s land surface areas. This is the ninth warmest such period since records began in 1850. The 2011/2012 La Nina ended in the beginning of 2012, and the Arctic sea ice reached its lowest extent on 16 September. During 2012, notable climatic anomalies and extreme events were observed worldwide. Extreme low temperature and cold waves hit the Eurasian Continent during late January through mid February. Extremely severe floods never seen in the past 50 years occurred in the Valley of Amazon River in May. From June to September, North America suffered the most severe drought since 1956. Since June, tropical storms and typhoons attacked East Asia, Southeast Asia and the east coast of America. The global extreme warm events mainly appeared in the central and southern parts of Europe, central and southern parts of North America, southern part of South America, the western, southern and northeastern parts of Asia while the global extreme cold events were mainly experienced in most of Asia, the east of Europe and parts of eastern America. Besides, extremely severe rainfalls were seen in central Europe, western Africa, central and southern parts of South Americal, South Asia, Southeast Asia and southern part of Northeast Asia. Analyses show that, atmospheric circulation anomalies are the direct causes of above global significant weather and climate events. In addition, with global warming, the westerly basic flow becomes weakening and the meridional circulations in middle and high latitudes becomes strengthening, leading to the enhanced persistence of anomalous circulations and favorable dynamic conditions for the formation of climatic anomalies and extreme events.