Historians have speculated for years that global environmental changes caused some ancient wars to ___1___, or even societies to collapse. Such connections may still exist—because new research finds that the risk of civil war in tropical countries increases during hot, dry El Nino years as ___2___ cooler La Nina periods. The study is in the journal Nature. [Solomon M. Hsiang, Kyle C. Meng and Mark A. Cane, Civil conflicts are associated with the global climate]

Researchers used a database of global conflicts over the last six decades, which included clashes resulting in at least 25 deaths in battle. They compared those data to the three- to seven-year cycling of El Nino. And they found that the risk of conflict doubled during El Nino years—but only in tropical countries most affected by the climate cycle. El Nino may have played a role in ___3___ a fifth of the 234 conflicts studied.

This study can’t determine a cause. But the researchers say hot El Nino conditions can ___4___, causing food shortages and sparking conflicts. And since El Nino can be predicted up to two years in advance, governments and NGOs might be better able to plan for the possibility of a civil war.
erupt opposed to spurring diminish harvests
历史学家很多年来一直有这样的猜想:某些古代战争甚至社会的衰退是由全球气候变化引起的。它们之间的微妙关系至今尚存——因为一项新的研究显示,相对较为寒冷的反圣婴现象发生年间,在干燥炎热的厄尔尼诺现象发生时,内战爆发的可能性比较大。该项研究报告刊登在《自然》杂志上。 研究人员研究了过去60年间全球的战争记录,其中包括死亡人数在25人以上的冲突事件。它们将这些数据和3至7年一循环的厄尔尼诺现象作比较之后发现,厄尔尼诺现象发生年间,战争发生的概率翻倍——不过仅限于受影响的热带国家。在研究人员研究的234场战争中,有五分之一很可能就是由厄尔尼诺现象引发的。 这项研究尚未能对厄尔尼诺引起战争的确切诱因下定论,不过研究人员称,厄尔尼诺现象能够导致庄稼减产,造成食物短缺,引起战争。好在厄尔尼诺现象提前两年就能预测到,政府和非政府组织可以为可能爆发的内战做一手准备。