A recent lame paper by researchers desperately trying to tie Syrian violence with global warming and climate change was completely eviscerated by a wide range of experts...in summation, it was an exceedingly stupid paper...plus, history of climate antiquity provides plenty of evidence that cooler temperatures provoke more war, rebellions and organized violence than warmer periods.....
This chart depicts historical precipitation and temperature reconstruction from northern China.
Overlaid on the chart by 'C3' are significant Chinese events from the past, along with identification of major solar states (minimums and maximums).
The scientists who compiled the precipitation/temperature records and produced the reconstructions had summarized that solar influence was climatically significant for China due to the affect on annual monsoons.
Using Wikipedia, major war/violence/political events were identified and then added to the chart (color bars).
To the more than casual viewer, it would certainly appear that a cooler climate regime has a higher association with extreme organized violence than a warmer period.
The chart's green curve indicates that those periods with less precipitation (i.e. droughts) are more common when cooler temps prevail - more arid conditions, with less food production make people (and societies) rather restless.
The unequivocal and indisputable climate research clearly demonstrates that climate change is constant; and when combined with historical accounts and anecdotal evidence, warmer climates tend to favor prosperity and peace outcomes while cooler periods provide more of the opposite.
Note: 'C3' originally wrote about this research in 2011. There was a recent article at Ice Age Now (and a YouTube video) using another 'C3' chart with significant Chinese events being overlaid on the Greenland ice core temp reconstructions (that prompted our doing the same for the above northern China chart). Wikipedia info page sources: here, here, here, here, here, here, here, here, here, here and here.