Climate is the average or statistical state of meteorological elements and weather phenomena for a long time, and the time scale is months, seasons, years, years to hundreds of years. Climate is measured by the characteristics of cold, warm, dry and wet, and is usually characterized by the average value and deviation value of a certain period. Climate is the general state of the atmosphere in a certain region of the earth for many years, and it is the comprehensive expression of various weather processes in this period. Various statistics (mean, extreme, probability, etc. Meteorological elements (temperature, precipitation, wind, etc.). ) is the basic basis for expressing climate. Climate is closely related to human society, and many countries have recorded climate phenomena for a long time. During the Spring and Autumn Period in China, the sun shadow was measured by a standard table to determine the season, and there were 24 solar terms and 72 climaxes in the Qin and Han Dynasties. Climate change has an important impact on human beings and natural systems. Because ecosystems and human society have adapted to today's and recent past climate, it will be difficult for people to cope with these changes if they adapt too fast. For many developing countries, this may have a very harmful impact on the basic living standards of human beings (housing, food, drinking water and health). For all countries, the increasing frequency of extreme weather and climate events will increase the risk of weather disasters. Climate change has both positive and negative impacts on China's economy and society, some of which are actually irreversible, so we should pay more attention to the negative impacts. According to statistics, from 1950 to 2000, especially after 1990, the economic losses caused by meteorological disasters increased sharply. There are two reasons, one is the increase of extreme weather events, and the other is the increase of China's overall economic volume, so the absolute value of economic losses has greatly increased. Most parts of China belong to subtropical monsoon climate, and the impact of climate change on agriculture is negative. It is predicted that by 2030, China's three major crops, rice, corn and wheat, will mainly reduce production except winter wheat. Climate change also has a great impact on water resources. Global warming accelerates the water cycle and increases the spatial heterogeneity of precipitation. Climate change also has an impact on major projects, such as the increase in precipitation in the upper reaches of the Yangtze River, which will lead to an increase in the frequency of geological disasters and have a certain impact on the safe operation of the Three Gorges Reservoir. In addition, climate change will also affect the Qinghai-Tibet railway and highway, greatly increasing the investment in railway and highway operation and maintenance. Like the whole world, China's climate and environment have also undergone tremendous changes. Climate warming has gone far beyond the general climate and environmental problems, and it has brought a very serious threat to China's economic and social development, and this threat will continue and intensify. Scientific and technological circles should pay special attention to climate change, actively take adaptation and mitigation measures, and constantly improve the level and level of climate system, ecology and environmental protection. This is an important content of fully implementing Scientific Outlook on Development and building a harmonious socialist society, and it is also the common aspiration of the government, the public and scientists.