China is a country with agriculture as the mainstay, and climate change has a direct impact on agricultural production in China. The climate change in China in the past 2000 years has a strong correlation with the rise and fall of dynasties. All dynasties with stable society, developed economy, strong national strength and expanded territory of population growth will be consistent with the warm climate.
However, the chaotic times of separatist regime, peasant uprising and foreign invasion mostly belong to the cold period or cold period in China's history. The main foreign invasion in the history of China is the invasion of nomadic people. In the cold and dry period, the nomadic people in the north will face the threat of water grass depletion and ecological deterioration, so they will expand to agricultural areas. Moreover, the earlier the Central Plains Dynasty was established before the nomadic regime, the higher the possibility of being conquered by nomadic people.
At the beginning of each dynasty, because of the long-term war, the population was greatly reduced, the land resources were relatively rich, and the food supply was sufficient, so social stability and development could be maintained for a period of time. With the increase of population, the rewards of various factors of production gradually decreased, and the food crisis led to the intensification of social contradictions and the decline of the dynasty.
After the war and famine, the population crisis disappeared and the new dynasty could go through the next cycle. In ancient China, due to the lack of industrial and commercial vitality and scientific and technological breakthroughs, agricultural society often fell into the Malthusian trap. If the linearly growing means of subsistence cannot meet the exponential population growth, poverty and war will occur, thus forming the "periodic law of dynasties."
The Influence of Climate on Han Dynasty
Qin and Han Dynasties were the first warm period in recorded history. At that time, subtropical plants such as rice and bamboo forests could be planted in the Yellow River basin. According to Historical Records, "Qilu has a thousand acres of mulberry horses, and Weichuan has a thousand acres of bamboo". Sang Ma and bamboo, which are only found in the south today, can be planted in the Weihe River Basin in Shandong and Shaanxi, indicating that the climate was warmer then than today. During the Qin dynasty, crops could be planted in today's desert Taklimakan area, which is also the reason why the Qin dynasty was strong.
The warm period of the Han dynasty lasted, and after the "rule of cultural scene", the society was stable and there was no war in the frontier for many years. With the accumulated material security for many years, Emperor Wu of the Han Dynasty took the initiative to expel the Xiongnu to West Asia and Eastern Europe.
During the reign of Emperor Guangwu of the Eastern Han Dynasty, Xiongnu suffered a rare plague of locusts, and Xiongnu was also divided into South Xiongnu and North Xiongnu. In the 26th year of Jianwu in the Eastern Han Dynasty (AD 50), the Southern Xiongnu couldn't bear it any longer and turned to the Eastern Han Dynasty for help. After that, Emperor Guangwu subsidized the Southern Xiongnu with 25,000 grains and nearly 40,000 cattle and sheep.
From the first year of A.D., the whole earth ushered in the intermittent cold period of the Little Ice Age, that is, a small cycle in the great cycle. With the attachment of the southern Xiongnu and its southward migration, Dou Xian, a famous star in the Eastern Han Dynasty, attacked the Xiongnu twice, defeated the main force of the Xiongnu in today's Altai Mountain area, and then surrendered more than 300,000 people in the northern Xiongnu, which also enabled the Han army to completely defeat the Xiongnu.
However, since the Western Han Dynasty proclaimed itself emperor in four years, the climate has entered a cold period, and there has been a scene of "snow in April and peaches and plums in autumn". Moreover, the history of China entered the troubled times of the late Han, Wei, Jin, Southern and Northern Dynasties, which lasted for more than 300 years.
According to Zhu Kezhen's "Climate Change in the History of China", it is found that during the cold period from north to south, from the 4th century to the 5th century, the average temperature was 3 degrees Celsius lower. If the average temperature drops by 1 celsius, the rainfall belt in China will move southward by 200-300 km, and the rainfall will also decrease by 100 mm. At that time, Shanxi and Hebei regions moved more than 500 kilometers to the south.
The movement of rain belt to the south means that the agricultural area will move to the south, and the arable land area will decrease accordingly. With the reduction of grain production, there will be famine everywhere. Not only did the nomads living in the Yellow River basin move southward in large numbers, but the nomads in the north also entered the * * * area in succession.
In the early years of the Eastern Han Dynasty, the Han Dynasty allowed the southern Xiongnu to move to Wuyuan area in Inner Mongolia, and the Xianbei nationality moved from Daxinganling area to Hulunbeier area in Inner Mongolia. In addition to Xiongnu and Xianbei, there are Qiang, Di and Jie ethnic minorities. When this wave of immigrants reached * * * in the Western Jin Dynasty, there were nearly half of the ethnic minorities in Guanzhong area.
Of course, a large number of * * * south, but also the main reason for the strong Dongwu and Shu Han. Wu Huan cavalry and other ethnic armed forces are also important military forces that Cao Wei family can pacify the world.
The rise and fall of Tang dynasty
In 600 AD, during the Sui and Tang Dynasties, the climate in China ended the cold period of nearly 600 years and entered a warm period. During the Tianbao period of the Tang Dynasty, Chang 'an even had bamboo forests in citrus reticulata. Good climatic conditions have prolonged the arable time of crops, improved the multiple cropping index, increased the yield to varying degrees, and achieved rapid economic development.
However, since the 8th century, the climate in the north turned cold, and the winter wind made the climate in East Asia dry. According to the Records of Five Elements in the New Tang Dynasty, there were 75 droughts and more than 40 famines in the following 290 years, almost once every two years and once every three years.
In the first year of Zhenguan, Emperor Taizong ordered the hungry people to go to other states for free support. During the Gaozong period, there were 12 droughts in 34 years, and Luoyang, the eastern capital, even appeared the scene of "man eating man". No rain for a long time has brought great obstacles to grain transportation, especially the grain supply in Chang 'an. During the Tang dynasty, a large number of people moved south, which promoted the economic development of Jiangnan. Chang 'an is the political center and Yangzhou is the economic center.
Yangzhou is the distribution center of water transportation in the south of the Yangtze River, and materials are transported from Yangzhou to Chang 'an via the Canal, Bianshui, Yellow River and Weihe River. In the Tang Dynasty, the winter wind was very strong and the summer monsoon was very weak, which caused droughts in the Yellow River and the Yangtze River basins at the same time or alternately.
In December of the first year of Guangming (AD 880), Huang Chao entered Chang 'an, proclaimed himself emperor and founded the country, and the Tang Dynasty became inseparable. Years of drought have caused financial difficulties and caused a tax struggle between the central government and the buffer areas. The local taxes handed over to the central government are often withheld by the buffer region, which raises the self-esteem of its soldiers, resulting in a situation of "emphasizing the inside and emphasizing the outside" and greatly weakening the centralization. According to historical records, when the Central Plains suffered a major natural disaster, the chieftain commanders of the frontier ethnic minorities took advantage of the chaos to plunder.
The influence of climate in Qing dynasty
The temperature in Qing Dynasty was 1 to 2 degrees Celsius lower than today. In the Qing dynasty, where agriculture was underdeveloped, natural disasters caused by low temperature had a certain impact on society. Since the Qing Dynasty introduced sweet potatoes and corn, the population was larger than that of the previous dynasties in most cases, and even reached the highest level of 440 million in the middle of19th century.
The population growth was slow in the early Qing Dynasty and rapid in the Kanggan period, and the whole growth continued until the outbreak of the Taiping Heavenly Kingdom. After the Taiping Heavenly Kingdom and the war of aggression by foreign powers, the population decreased by 1/5, and it was not until the late Qing Dynasty that the population recovered to its peak.
Compared with the previous dynasties, the rate of population appreciation in Qing dynasty increased obviously. In the case of no major innovation in agricultural technology in Qing Dynasty, population expansion led to Malthus crisis. /kloc-since the 0/9th century, the climate in the Qing Dynasty has become cold and peasant uprisings have been frequent. Of course, famine was an important factor in the uprising.
Why does climate change trigger dynasty change?
In history, the nomadic people in the north were mainly animal husbandry, and the cold and dry climate was not conducive to agricultural production in the Yellow River basin, nor to the development of nomadic people. If the temperature drops by 2 degrees Celsius, the growth cycle of pasture will be shortened by 40 days, resulting in a sharp drop in grassland grass production. Due to the pressure of life, nomadic people must go south.
And * * * in the central plains, because of the decline in grain production, leading to a decline in national strength, coupled with the continuous peasant uprising, internal friction, but also exhausted the state treasury, so unable to resist the attack of nomadic people, only to withdraw south, so nomadic people occupied * * * farmland, and the dividing line between agriculture and animal husbandry moved south.
When the temperature rises, agricultural production will be stable, and grain output will increase. If I meet a wise monarch again, I won't toss about it. After a period of development, the national strength will gradually become stronger. Then it will launch a powerful attack on the nomadic people in the north and recover the lost land, so the pasture will become farmland and the dividing line between agriculture and animal husbandry will move northward.
At the same time, the economic center of the * * region will also be affected by the climate. When the cold season comes, the focus of agriculture will move south, and the ethnic minorities in the south will be weak. Therefore, if China people move south, there will be less conflicts, and even more advanced planting techniques and advanced culture will be brought to the south. For example, Yongjia Du Nan in the Wei, Jin, Southern and Northern Dynasties not only established the * * * regime, but even dominated the cultural direction.
During the Southern Song Dynasty, a large number of * * * moved into the Yangtze River valley, making the south of the Yangtze River rich and the economy of the south gradually surpassed that of the north. On the surface, the southward movement of economic center is the result of the massive invasion of northern nomads and the southward movement of political center. In fact, the cold climate is the potential driving force.
The peak of the number of wars in China usually occurs in the cold period, that is, there are more wars in cold weather. From the end of Tang Dynasty to the end of Qing Dynasty, the three major war peaks were the peasant uprising led by Zhu Yuanzhang at the end of Yuan Dynasty, the peasant uprising led by Li Zicheng at the end of Ming Dynasty, the invasion of Manchu Dynasty and the peasant uprising of Taiping Heavenly Kingdom at the end of Qing Dynasty, all of which occurred in the cold climate.
The cold climate affects the production of agriculture and animal husbandry, which leads to the shortage of production and living materials and often leads to war. This is an inevitable choice made by people under the pressure of survival needs. The cold climate is often accompanied by drought, which leads to the decline of agricultural production level, land output, farmers' inability to bear taxes and social contradictions. When the contradiction is completely intensified, farmers rise up, nomads take advantage of it and a large-scale war breaks out.