中国热带的小冰期及其环境效应

The Little Ice Age and Its Environmental Effects in the Tropical Zone of China

中国热带小冰期的年代和阶段划分 ,前人至少有 6种不同意见。文中选取 87个冷冬年份的雪、霜、冻害的史籍资料 ,并按照灾害出现地点的 3个地带 (亚热带南部、热带北部、热带中部 ) ,认为小冰期为 1 485～ 1 897年 ,并可分出 3个寒期即 1 485～ 1 52 7年、1 60 6～ 1 767年、1 835～ 1 897年 ,其间为 2个冷期。 3个寒期从老到新越来越强。小冰期年均温比现今的降幅小于0 .6℃ ,但极端低温曾降至 - 1℃以下。小冰期的环境效应表现在降雪南界南移、灾害频发、农业歉收、生态退化。

According to the historical data, climate was probables warm during the Medieval Period, the Yuan Dynasty and former part of the Ming Dynasty in China's tropical zone. Based on the historical records about cold winter with snowfall, frost or freeze occurring in the tropical zone from 1245 to 1915, it has been found out that the Little Ice Age began in 1485 and ended in 1897. The records about historical weather are divided into three groups according to the locations of cold winter occurring in the subtropical, northern tropical and central tropical. Except the first which is not located at tropical, the second and the third kinds are called cool year and cold year, respectivily. As a result, it has been found out that there were three cold periods, i.e. the first (Ⅰ, 1485 1527), the second (Ⅱ, 1606 1767) and the third (Ⅲ, 1835 1897) while two cool periods intercalated in the cold ones. The dating of the cold periods was later than that of north China. The frequency of cold winter got higher and higher from period Ⅰto period Ⅲ, but the amplitude of drop in annual mean temperature was <0 6℃ than present all of the three periods. However the maximum of low temperature reached -1 0℃ resulting in the removal of the south limit of snowfall southward by 2~3℃ latitudes or 1 0~1 5℃ of drop in temperature. Some natural disasters including flood, drought, typhoon and earthquke were frequent in the Little Ice Age especially the drought disasters which shows a desiccation trend of climatic change. The impacts of climate in the Little Ice Age on the poor agricultural harvest, ecological degeneration, migration of population, famine and society turbulence are also discussed in this paper.