关于唐代气候冷暖问题的讨论

本文就历史文献记载的资料详细讨论了唐代气候冷暖两方面的证据。从现有支持气候温暖的证据来分析,它们难于确定相应的气候限制因子,并且类似的证据存在于不同的气候条件下。从有关的寒冷资料分析,唐代气候至少可分为两大阶段,8世纪50年代以前大体与现代相差不大,但8世纪60年代以后气候变冷,某些时段寒冷的特征可与明清小冰期相似。

CLIMATE IN TANG DYNASTY OF CHINA: DISCUSSION FOR ITS EVIDENCE

For the temperatural properties of the climate in Tang Dynasty, a famous one inhistory of China, there are different opinions upon the climate in Tang dynasty.The subtropical species Plum trees had been planted in the imperial garden in thecapital Chang'an, which was managed elaboatly and was used as blooming admiration.So, even though it is originally growing as one of subtropical species, its climaticrestrictive condition had been changed by gardeners' management when it was plantedas a blooming-admiration species in the imperial garden at the capital Chang' an.The same samples, Plum trees were planed in northern area, can also be found inYuan and Qing Dynasties in Kaifeng, Beijing, Jinan and Anyang. If the gardenedPlum could serve as indicator for warm climate, we had to admit that the climate inYuan and Qing Dynasties were also warm. Orange tree is also a subtropical plantand appeared in the imperial garden in Chang' an. By comparing the Orange treedistribution (economically, not as an admiration)with river freezing phenomena, we canfind that the rivers in the distribution zone of Orange tree are not iced annually. Butthe rivers nearby the capital Chang' an in Tang dynasty were recorded to freeze andunfreeze in winter and next spring every year. It is clear that the cold winter did notsuit Orange tree living. That means the elaborate management on the warm-likespecies have changed the local condition, which made the species lived in a morenorthern place. Such species loses their rationality as an indicator for natural climaticcondition.Tame elephant contributed by some southern kingdoms and existed in Chang' an,is other evidence used as indicator for warm climate in Tang Dynasty. Beforeexplaining its climatic significance, another analogy can be viewed, which comes fromQing Dynasty. There was a special office agency in Capital Beijing, which main dutywas to manage and feed unusual animals, such as hoe elephant In that bine,thetame elephant serviced in ceremonial occasions.So we would fall into self-contradictionwhen we admit tame elephant is a warm indicator, because Qing Dynasty was in theLittle Ice Age and Beliing locates more northern than Chang' an. This is anotherexample that human activities change the climatic condition of some species. Therefore,such species under human control are impossible to be used as climatic indictor.All of the recorded cold eventS in bine series (such as heavy snow, abnormalsnowing and frosting date, the sea water icing and so on) reveal that theyconcentrated in the second half of Tang Dynasty (760' s- 900's). An accumulatedcurve is used to shows the feature. For the reason that it could be other facts thatcause the concentration of cold events, for example, the record missing in some period,a warm event accumulated curve is used to examine above phenomenon. The warmcurve shows that warm events decline after the middle of 8th century, and processesan opposite feature with the cold event curve. It can be confirmed that theconcentration of cold events means that the climate have changed to cold since themiddle 8th century. There was a cold trough at 800' s, in which some decades heldcold feature similar to that of the Little Ice Age, for example the sea water lcing innorthern pan of Jiangsu province.Sea water icing in northern part of Jiangsu Provinceindictes a severe cold winter. In the winter 1935-1936, the sea water in Bobai seawas frozen. This winter is so cold that it is listed as a second coldest winter in the20th century, but no report said the sea water icing happened in the northern part ofJiangsu province. So, in historical bines, the cold events, sea warer icing in thenorthern pall of Jiangsu Province, were only found in Tang Dynasty and Ming toQing Dynasties (same as the Little Ice Age) of the last millennium. Otherpheonological evidence of a cold climato is from a Japanese Shaman's travels. Forexample, the icing in Yangzhou began at Oct. 31 in the year 838, but samephenomenon in present begins evenly at Nov. 25. At the end of 9th century, therecord in a farming book shows t