When farming fails, fighting starts.
根据一篇本星期四发表在英国《自然》周刊上 的研究文章，在许多历史学家眼里中国历史上辉煌强大的唐朝毁灭在季风周期变化上。以丰富多彩的文学艺术和与印度中东的繁荣贸易而举世闻名的中国唐朝延续了将近三个世纪（618AD-907AD），最后战乱和农民起义中灭亡了。
德国波茨坦GFZ(Geoforschungszentrum)研究机构以杰拉德 黄为首的科学家在经过对在湛江取样的沉积核进行研究后得出了这一结论。
他们认为分析取样中的磁性沉积物和钛含量是显示东亚冬季风系统周期的重要标志。
他们发现在一万五千年的时间里，东亚有三个强烈的冬季风和三个虚弱的夏季风时期。
前两个季风变化时期发生在冰川季最后两个关键阶段，最后一个季风变化期发生在公元700AD到900AD之间。每个季风变化周期都伴随着寒冷的气候。
唐朝命运的转折点发生在公元751AD，这一年唐朝的军队被阿拉伯人击败。
最终使唐朝覆灭的原因是由于长期的干旱和夏季不正常降雨而造成粮食歉收和因而引发的农民起义。最后，这些农民起义导致唐朝在公元907年灭亡。
这个研究小组还认为季风周期的变化不但影响到了东亚，同样影响了美洲大陆。
季风变化引起的干旱同样影响到了中美洲，同样是举世闻名的玛雅文化与唐朝在同一起消失了。
从中国湛江的地质取样和从委内瑞拉卡里亚科盆地的取样有着惊人的相似之处。
两地的取样证明了从公元750AD开始，每三年为一个周期就发生一次干旱。
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.
