What does extreme weather have to do with?

Extreme weather and climate events mean that the state of weather (climate) seriously deviates from its average state, which is difficult to occur statistically. Generally speaking, extreme weather and climate events refer to small probability events that occur once every 50 years or once every 100 years. With global warming, the frequency of extreme weather and climate events has changed, showing an increasing trend. The latest assessment report issued by the United Nations Intergovernmental Panel on Climate Change (IPCC) IPCC)2007 shows that extreme weather events, especially extreme events such as heavy rainfall and high temperature heat waves, have been increasing in the past 50 years, and it is expected that such extreme events will appear more frequently in the future. The World Meteorological Organization (WMO) issued a statement on this year's extreme events, saying that this year's extreme events not only increased significantly around the world, but also spread widely, including heavy rainfall in Southeast Asia, an unprecedented tropical storm in the Gulf in June, heavy rainfall and floods in southern China, floods in Britain from May to July, heat waves in Southeast Europe and Russia, and abnormal snowfall in parts of South Africa and South America. Global warming is the background of frequent extreme weather and climate events. According to the data of the World Meteorological Organization, the global surface temperature in June and April 2007 was 65,438 0.89℃ and 65,438 0.37℃ higher than the historical average, respectively, both exceeding the highest level of 65,438 0.998, which was the highest value in the same period on record. In 2006, the national average annual temperature was higher than normal 1. 1℃, which was the warmest year since 195 1. From June to July this year, the national average temperature was 1.4℃ higher than normal, the highest in history since 195 1, and it was also a continuous high year since 1997. The winter temperature in China is also obviously high, and there have been 2 1 warm winters since 1986. On February 5th this year, the highest temperature in Beijing reached 16.0℃, setting a record for the same period since meteorological data were available for 1840. On February 6th, the highest temperature in Nanjing reached 23.9℃, which is also the highest temperature in the same period once in a hundred years. From the perspective of probability theory, if the temperature in a certain area or place is normally distributed under the average condition for many years, the probability of weather is the highest, the probability of hot and cold weather is small, and the probability of extremely cold or hot weather is even smaller. However, due to the influence of global warming, the average temperature in this area will rise, and the probability of high temperature weather will increase obviously. Extremely hot weather, which was rarely seen before, may also appear frequently now, and extreme events such as high temperature heat waves will become frequent. If the variance of temperature changes increases, extreme weather will occur more frequently. According to the principle of meteorology, global warming makes the surface temperature rise, which leads to the increase of water surface evaporation and the acceleration of water circulation, which will enhance the storm energy and complete more precipitation in a shorter time, which may increase the frequency of heavy rain, extreme precipitation events and local floods. Strong convective weather such as tornadoes, strong thunderstorms, strong winds and hail will also increase in some areas; In addition, due to the accelerated evaporation of plants, soil, lakes and reservoirs, the increase in water consumption and the rising temperature, some areas will suffer more frequent, more lasting or more serious droughts; The increase of atmospheric humidity may also increase the intensity and frequency of snowstorms in some cold areas.

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