When farming fails, fighting starts.
根據一篇本星期四發表在英國《自然》周刊上 的研究文章，在許多曆史學家眼裏中國曆史上輝煌強大的唐朝毀滅在季風周期變化上。以豐富多彩的文學藝術和與印度中東的繁榮貿易而舉世聞名的中國唐朝延續了將近三個世紀（618AD-907AD），最後戰亂和農民起義中滅亡了。
德國波茨坦GFZ(Geoforschungszentrum)研究機構以傑拉德 黃為首的科學家在經過對在湛江取樣的沉積核進行研究後得出了這一結論。
他們認為分析取樣中的磁性沉積物和鈦含量是顯示東亞冬季風係統周期的重要標誌。
他們發現在一萬五千年的時間裏，東亞有三個強烈的冬季風和三個虛弱的夏季風時期。
前兩個季風變化時期發生在冰川季最後兩個關鍵階段，最後一個季風變化期發生在公元700AD到900AD之間。每個季風變化周期都伴隨著寒冷的氣候。
唐朝命運的轉折點發生在公元751AD，這一年唐朝的軍隊被阿拉伯人擊敗。
最終使唐朝覆滅的原因是由於長期的幹旱和夏季不正常降雨而造成糧食歉收和因而引發的農民起義。最後，這些農民起義導致唐朝在公元907年滅亡。
這個研究小組還認為季風周期的變化不但影響到了東亞，同樣影響了美洲大陸。
季風變化引起的幹旱同樣影響到了中美洲，同樣是舉世聞名的瑪雅文化與唐朝在同一起消失了。
從中國湛江的地質取樣和從委內瑞拉卡裏亞科盆地的取樣有著驚人的相似之處。
兩地的取樣證明了從公元750AD開始，每三年為一個周期就發生一次幹旱。
附原文:
Published online: 13 July 2007; | doi:10.1038/news070709-13
China had more wars in cold weather
Reduced agricultural productivity seems to trigger armed conflict.Most of the armed conflicts in eastern China over the past 1,000 years were triggered by food shortages caused by climate, say researchers.
The finding lends weight to the idea that future climate change, resulting in water and food shortages, might have similar effects, says Earth scientist David Zhang, of the University of Hong Kong. "Regions with rich resources and those lacking resources could be hot spots for conflicts."
Between 1000 and 1911, there were 899 wars in eastern China, where most of the country's food is grown. Zhang's team classified each decade as a time of either very high (more than 30 wars), high (15-30 wars), or low (less than 15 wars) conflict.
Over the same period, climate data for the Northern Hemisphere show six major cycles of warm and cold phases. Crop and livestock production dropped significantly during the cold phases.
All four decades of very high conflict, and most periods of high conflict, coincided with cold phases, they found. Warfare generally lagged 10-30 years behind the start of a cold phase.
"In situations of ecological stress, warfare could become the ultimate means of redistributing shrinking resources," the team writes in Human Ecology1.
"The result surprised me very much," says Zhang. "All high war periods and dynastic changes occurred during cold periods. I felt that human beings were still animals."
Rising tensions
The match between climate and warfare "would seem to make perfect sense", says economist Gary Yohe of Wesleyan University in Middletown, Connecticut, a contributor to the most recent Intergovernmental Panel on Climate Change.
He agrees that migrations or shortages brought on by climate change could lead to increased tensions and warfare. "The potential for human conflict within and across national boundaries is certainly something that climate change could exacerbate," he says. "There is a long history of nation states invading other nation states for natural resources."
Recently, a United Nations report declared that climate change was one of the causes of the conflict in Darfur, although experts on the region have criticized this conclusion as being too simplistic (see 'Darfur's climate roots challenged')
Sinologist Rudolf Wagner of the University of Heidelberg in Germany says that poor growing weather would be one of several contributing factors for war in China. "In extreme cases, I think there is definitely something to it."
But, he adds, organizational, social and political factors — such as whether governments could control their territory, and how they treated their people — are also important. "The paper is interesting but I think a bit overdone," he says.
Zhang, however, believes that the strife-inducing effect of cold weather was probably not confined to China. "In the coldest period of the Little Ice Age, we can find the general crisis of the seventeenth century in Europe, Japan, Korea and the Ottoman Empire," he says.
